Cannabis & Cannabinoids · Terpenes · The cool, camphor-like scent molecule of eucalyptus oil, also in rosemary, bay, sage and some cannabis

Eucalyptol (1,8-Cineole)

Q: What is eucalyptol?

Eucalyptol is the main scent compound of eucalyptus oil, also called 1,8-cineole or cineole (C10H18O). It is found in rosemary, bay laurel and sage oils and in some tea tree types, and it is reported in hemp and cannabis.

Q: Is eucalyptol the same as eucalyptus oil?

No. Eucalyptus oil is a mixture. In one E. globulus oil, 1,8-cineole was 63.1%, with p-cymene, alpha-pinene and limonene. Poisoning reports and EU rules are about the oil; capsule trials used purified cineole.

Q: Is there human research on eucalyptol?

Yes, more than for most terpenes: randomised trials of cineole capsules for COPD, asthma, bronchitis and sinusitis in adults. The main ones were funded by the maker (Cassella-med) and are single trials, mostly from one research group. There is no trial of eucalyptol from cannabis.

Q: Does it help with COPD or asthma?

In single trials cineole capsules added to usual treatment went with fewer COPD flare-ups and better asthma lung function and symptoms. Evidence is low certainty. A 2026 meta-analysis ranked cineole first for fewer flare-ups, but it is an indirect ranking. People should keep taking prescribed medicines and ask their doctor.

Q: Did every trial show benefit?

No. A double-blind trial of a three-terpene capsule (eucalyptol, limonene, pinene) added to a steroid nose spray missed its main goal at week 8 (p = 0.093). It is a mixture, not eucalyptol alone.

Q: Who paid for the research?

The COPD and bronchitis trials were funded by a grant from Cassella-med, which makes a cineole product. A 2024 cold trial was funded by Cassella-med and MCM Klosterfrau, and one review has an author employed by Cassella-med. For other trials the abstract does not state funding.

Q: Is eucalyptus oil dangerous if swallowed?

Yes, especially for small children. Hospital reports describe drowsiness, vomiting, unsteadiness and seizures; a children's hospital guideline says 5 mL or more of the pure oil can cause coma. Call a poison centre or emergency services at once if a child may have swallowed any.

Q: Is it safe for young children to breathe or have on the skin?

The EU herbal committee says eucalyptus oil medicines must not be used under 24 months because of laryngospasm, nor in children with seizures; inhalation under 3 years is listed as not established. Seizures have also been reported after eucalyptus vapour. Keep it away from small children.

Q: Is it safe in pregnancy?

Not known. The EU herbal committee says use in pregnancy and breastfeeding is not recommended because safety has not been established. Ask a doctor.

Q: Does eucalyptol relieve pain or make cannabis work better?

Unknown. Rodent tests show less pain behaviour at large doses, one trial of smelling eucalyptus oil after knee surgery found lower pain scores, and a prediction model named eucalyptol as a key predictor of relief in cannabis users. None of this shows eucalyptol is the cause.

1,3,3-trimethyl-2-oxabicyclo[2.2.2]octane (1,8-cineole), C10H18O · also called Eucalyptol, cineole, 1,8-cineole, 1,8-cineol, cajeputol, 1,8-epoxy-p-menthane (1,4-cineole is a different molecule)

Eucalyptol is a small plant molecule (a monoterpenoid with ten carbons and one oxygen bridge). It is the main compound of eucalyptus leaf oil and is found in rosemary, bay laurel and sage oils and in some tea tree types. It is also reported in hemp and cannabis. It is one of the few terpenes tested in randomised trials in people: cineole capsules for COPD, asthma, bronchitis and sinusitis, mostly funded by the maker. Swallowed eucalyptus oil is a serious poison for small children.

General information, not medical advice. Last substantive update October 25, 2026 · Not medically reviewed. A named clinician has not signed off on this page. How this page is made

About Eucalyptol (1,8-Cineole)

Eucalyptol (1,8-cineole) is the main scent compound of eucalyptus oil. It is also in rosemary, bay laurel and sage oils, in some tea tree types and in some hemp and cannabis. Randomised trials of cineole capsules in COPD, asthma, bronchitis and sinusitis were mostly funded by the maker and are single trials with modest p-values. Swallowed eucalyptus oil poisons small children, with seizures and coma reported. Our cannabis lab data hold no eucalyptol measurements, though some cannabis papers report it.

What it is

Eucalyptol is the same molecule as 1,8-cineole and cineole: C10H18O, PubChem compound 2758, IUPAC name 1,3,3-trimethyl-2-oxabicyclo[2.2.2]octane. It is a monoterpenoid, a ten-carbon plant molecule with an oxygen bridge. 1,4-cineole is a different molecule with different behaviour in lab tests.

In human liver tissue it is broken down mostly by the enzyme CYP3A4. How plants and cannabis make it was not found in the sources read.

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Where you meet it

Eucalyptus leaf oil: 63.1% 1,8-cineole in one E. globulus oil, and trial abstracts call it the main compound of eucalyptus oil. The Pharmacopoeia limit was not read. Other oils, each from one sample: rosemary 26.54% (with alpha-pinene 20.14%), bay laurel leaf 31.9% (with sabinene 12.2% and linalool 10.2%). Sage oil lists it among its main compounds with camphor and thujones, but the abstract gives no percentage. In tea tree, 615 wild trees gave six oil types, with some dominated by 1,8-cineole and others by terpinen-4-ol; what standard tea tree oil contains was not read. Amounts differ by species, place and batch, so a percentage in one oil does not apply to the next.

In cannabis, a hemp distillation study names a "high eucalyptol" oil fraction, another hemp study found 1,8-cineole varied with planting system, a 2025 medical-cannabis study names eucalyptol among key predictors of pain relief, and a 2022 extract study measured it among 20 terpenes. None of the abstracts gives a flower amount for high-THC cultivars.

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What the lab numbers show

Our cannabis lab data hold no measurements of eucalyptol: none of the strains in our data has a value for it. That does not mean cannabis has none. Some cannabis and hemp papers report it (see "Where you meet it"), but not in the dataset behind our strain pages.

Because there are no values, we do not rank strains for eucalyptol. The numbers in lab reports are measurements of flower content and say nothing about effects, and the same strain name can have very different chemistry from sample to sample. A lab report for the specific batch is the only way to know.

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The popular claims

"Eucalyptol is a proven treatment for lung disease." Cineole capsules were tested in trials, but the main ones were funded by the maker, each is one trial, and the COPD, asthma and bronchitis trials come from one research group. Cineole capsules are also not the same as breathing eucalyptus vapour, smoking or vaping cannabis, or swallowing the oil.

"Eucalyptol is why a cannabis strain relieves pain." One 2025 prediction model named eucalyptol as a key predictor of pain relief among 329 patients, but the model was only a little above chance (AUC 0.63) and it shows an association, not a cause. In a cell study, eucalyptol content showed a weak, non-significant link to cancer-cell killing (p = 0.094) and no cancer treatment is shown.

"It is natural so it is safe." Pure eucalyptus oil has caused seizures and deaths when swallowed. Keep it away from small children.

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What the research shows

Human, cineole capsules: COPD (242 adults, 6 months, flare-ups lower than with placebo; funded by Cassella-med), asthma (247 adults, 6 months, better lung function, symptoms and quality of life, with p-values near 0.05 for single measures), steroid-sparing in severe asthma (32 adults, 36% against 7% dose cut), acute bronchitis (242 adults, fewer cough fits at day 4; funded by Cassella-med), and acute sinusitis (152 adults, symptom score 3.0 against 9.2 at day 7). A branded capsule (Soledum) was tested in an open-label cold trial with no placebo group, funded by its makers. A 2023 network meta-analysis rated cineole for acute post-viral sinusitis as moderate certainty, and a 2026 one ranked it first for COPD flare-ups and side effects.

Null or weaker results: a double-blind trial of a three-terpene capsule (eucalyptol, limonene, pinene) added to a steroid nose spray missed its main goal at week 8 (p = 0.093). A second trial of the same mixture after sinus surgery found slightly better scan scores. These are mixtures, not eucalyptol alone.

Pain: one trial of smelling eucalyptus oil after knee surgery found lower pain scores than almond oil, in a whole oil, probably unblinded in practice. Animals and cells: in rats and mice cineole lowered swelling and pain behaviour at large doses and made mice sleepy; in human cells it lowered NF-kappa-B activity; it activates TRPM8 and blocks TRPA1 in cells.

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Regulatory status

In the EU, the herbal committee (EMA/HMPC) adopted a final monograph on eucalyptus oil on 20 November 2024: a traditional-use medicine for cough with a cold and for localised muscle pain, based on long use only, with the age limits and contraindications described above. We read the monograph on 2026-10-25.

In the US, 21 CFR 172.515 lists "Eucalyptol; 1,8-epoxy-p-menthane; cineole" among synthetic flavouring substances allowed in food under stated conditions (eCFR version dated 2026-10-01, read on 2026-10-25). That is a food-flavouring rule and says nothing about vaping, supplements or cannabis products. We did not read any regulator source on cineole capsules or cannabis products, and this page gives no legal advice.

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At a glance

Traditional uses history, not proof

Eucalyptus oil is a traditional herbal medicine for cough with a cold and for localised muscle pain, based on long use (EU herbal committee, 2024)
Flavouring ingredient in food: the US FDA lists eucalyptol among allowed synthetic flavourings (eCFR)
Cineole capsules are sold as a medicine for airway disease in some countries (a branded capsule is named in a 2024 trial)
Plants that contain it have their own traditional uses, but those are uses of the plants, not of eucalyptol

Studied for research

COPD flare-ups: one company-funded trial plus a meta-analysis ranking, low
Asthma and steroid tablets: one trial each, low and very low
Acute bronchitis and acute sinusitis: one trial each; sinusitis moderate in a network meta-analysis
Common cold: open-label, company-funded, very low
Sinus surgery recovery: a three-terpene mixture, one small gain and one missed goal
Pain after knee surgery (smelling the oil): one trial, very low
Pain, swelling and inflammation: cells and animals, very low
Cannabis studies: associations only, insufficient

Main compounds

1,8-Cineole, C10H18O (PubChem CID 2758)
1,4-Cineole, a close but different molecule
Other compounds in the same oils: alpha-pinene, limonene, terpinen-4-ol, camphor, thujones
Related cannabis terpenes: limonene, pinene, linalool, terpineol

Common forms

Part of eucalyptus, rosemary, bay laurel and sage essential oils
Cineole capsules (a medicine in some countries)
Three-terpene capsules (eucalyptol, limonene, pinene) used in China
Natural part of some hemp and cannabis products
Pure compound in lab studies

Research links: PubChem: 1,8-Cineole · EU herbal monograph on eucalyptus oil (EMA, 2024) · Royal Children's Hospital Melbourne: Eucalyptus Oil Poisoning · Cineole capsules in COPD, Respiratory Research 2009 (PubMed) · Network meta-analysis of herbal medicines for rhinosinusitis (PubMed) · Research Library · Genes & Biomarkers Library

What it is and its history

Name: Eucalyptol (1,8-cineole): a plant scent molecule, also called cineole. 1,4-cineole is a different molecule.
Chemical name: 1,3,3-trimethyl-2-oxabicyclo[2.2.2]octane
Other names: Eucalyptol; Cineole; 1,8-Cineole; 1,8-Cineol; Cajeputol; Eucalyptole; 1,8-Epoxy-p-menthane; Zineol; Eukalyptol; 1,8-Oxido-p-menthane
Common names: Eucalyptol (English); Cineole / 1,8-cineole (English)
Formula: C10H18O
Molecular weight: 154.25
CAS number: 470-82-6
PubChem ID: 2758
Chemical class: Monoterpenoid: a ten-carbon plant molecule with a ring and an oxygen bridge (a cyclic ether, called an oxide in one abstract). Formula C10H18O
How the plant makes it: Not verified here. None of the sources read describes how plants or cannabis make 1,8-cineole. Cannabis makes terpenes in resin glands of the female flower, but the route for this one was not read.
Where it is found: Eucalyptus globulus leaf oil: 1,8-cineole was 63.1% in one oil (p-cymene 7.7%, alpha-pinene 7.3%, limonene 6.9%). Trial abstracts call it the main constituent of eucalyptus oil. The Pharmacopoeia percentage was not read.; Rosemary essential oil: 26.54% in one oil, with alpha-pinene 20.14%.; Bay laurel (Laurus nobilis) leaf oil from southern Italy: 31.9%, with sabinene 12.2% and linalool 10.2%.; Sage (Salvia officinalis) oil: one of the main compounds with camphor, thujones, borneol and viridiflorol; the abstract gives no percentages.; Tea tree (Melaleuca alternifolia): six oil types in wild trees. One is dominated by terpinen-4-ol, one by 1,8-cineole and three more by 1,8-cineole with different amounts of terpinen-4-ol or terpinolene. What standard tea tree oil contains was not read.; A review says cineole is also present in plants of the mint (Lamiaceae), myrtle (Myrtaceae) and ginger (Zingiberaceae) families.; Hemp (Cannabis sativa): named as a hemp essential oil compound ("high eucalyptol EO") in a distillation study, and 1,8-cineole varied with planting system in another. Neither abstract gives a high-THC flower amount. A 2025 medical cannabis study and a 2022 extract study also name eucalyptol among the terpenes measured.; Our cannabis lab data hold no measurements of eucalyptol.
Related or similar compounds: Name: 1,4-cineole; Note: A close relative also found in eucalyptus oil. In cell tests it switched on both the cold sensor TRPM8 and the irritation sensor TRPA1, whereas 1,8-cineole blocked TRPA1. It also appears separately on the FDA flavouring list.; Name: Eucalyptus oil; Note: The oil is a mixture, mostly cineole in the E. globulus oil read (63.1%), but with other compounds. Safety reports about "eucalyptus oil" are not reports about pure cineole.

Traditional use and history history, not clinical proof

Tradition or era	Documented use	Source
Traditional herbal medicine for cough and muscle pain	The EU herbal committee classes eucalyptus oil as a traditional herbal medicine for relief of cough with a cold and localised muscle pain, exclusively on the basis of long-standing use (monograph first adopted 2014, revised 2024).	EMA/HMPC/320292/2023 (read as PDF)
Traditional medicine in many plants (review)	A 2023 review says cineole comes from eucalyptus, rosemary and camphor laurel and has a long history of use in traditional medicine. Dates and places were not given in the abstract.	Hoch et al 2023 (abstract only)
Food flavouring	The US FDA lists eucalyptol (1,8-epoxy-p-menthane; cineole) among synthetic flavouring substances permitted in food under stated conditions.	21 CFR 172.515 via eCFR
Modern capsule medicine	Cineole capsules were tested for COPD, asthma, bronchitis and sinusitis in German trials from 2003 to 2013. A branded capsule (Soledum) is named in a 2024 trial. When it was first sold was not found in the sources read.	Trial abstracts (see Evidence tab)
Wikipedia and general-encyclopedia history (NOT verified)	Claims about discovery in the 1800s, names such as "cajeputol", or history in perfumery were not checked against a source read. Not used.	None read

History shows how a substance was used or discovered. It does not show that a product works or is safe today.

What is inside, and how it may work

What it contains and how those compounds act in cells and animals. Laboratory and animal mechanisms are not proven effects in people.

Main compounds

Compound	Family	Where it is concentrated	Activity studied	Level of evidence
1,8-cineole (eucalyptol) PubChem 2758	Monoterpenoid cyclic ether	Leaf essential oils of eucalyptus, bay laurel, rosemary, sage and some tea tree types 63.1% in one E. globulus oil; 31.9% in one bay laurel oil; 26.54% in one rosemary oil. Varies with plant, place and batch.	Tested in people as capsules for airway disease; lab and animal work on inflammation and pain sensors. ^{41 7}	Human (capsules)
2-exo-hydroxy-1,8-cineole	Oxidised cineole (liver breakdown product)		The main product of cineole oxidation by human liver CYP3A4 in lab tests. ²⁵	Laboratory research
alpha-Pinene and limonene	Monoterpenes	Found with cineole in eucalyptus oil (7.3% and 6.9% in one oil) and rosemary oil (alpha-pinene 20.14%)	Combined with eucalyptol in the three-terpene capsules (ELP) tested in sinus trials. See the limonene and pinene pages. ^{46 14 12}	Human (mixture)
Terpinen-4-ol	Monoterpene alcohol	Tea tree oil; one oil type is dominated by it, while others are dominated by cineole	Not studied here; named only to show which tea tree type is meant. ¹¹	Not assessed
Thujones and camphor	Other sage-oil compounds	Sage oil, next to cineole	A sage oil abstract calls thujones toxic and notes high levels in Estonian sage. ³¹	Plant analysis

Mechanisms, receptors and pathways

Target or pathway	Gene or receptor	What was found	Level
NF-kappa-B signalling	NFKB1 / RELA (p65), IkappaB-alpha	In human cell lines and blood cells 1,8-cineol reduced movement of NF-kappa-B p65 into the nucleus and the activity of its target genes. ⁷	Lab
Cold and irritation sensors	TRPM8 (activated) and TRPA1 (blocked)	1,8-cineole activated human TRPM8 and blocked human TRPA1; in animals it reduced sensory irritation caused by TRPA1 triggers. ³⁷	Lab and animal
Liver breakdown	CYP3A4 (and CYP3A5 at about a quarter of the rate)	Human liver microsomes oxidise cineole to 2-exo-hydroxy-1,8-cineole mainly through CYP3A4. ²⁵	Lab
Cytokines, interferon regulation and mucin genes (review)	IRF3, TNF-alpha, IL-1 beta, IL-6, IL-8, MUC2, MUC19	A review of lab work in human monocytes and lymphocytes states that cineole lowers these inflammation signals and mucin genes, and adds to budesonide in vitro. ¹⁶	Lab
Opioid receptors	mu-opioid receptor	Naloxone did not block the antinociceptive effect of cineole in mice and rats, so opioid receptors do not seem to be involved. ^{33 20}	Animal research
Cannabinoid receptors (CB1, CB2)	CNR1, CNR2	No source read tested eucalyptol at cannabinoid receptors. The cannabis studies read are associations or whole-extract cell tests. ^{8 19}	Not tested

Absorption, metabolism and elimination

Absorption: By mouth: 1,8-cineole was found in nasal polyp tissue of 30 people after 14 days of an oral cineole medicine. Through skin (cadaver skin, ex vivo): from a rub, eucalyptol built up in the skin layers more than the other terpenes but did not pass into the receiving fluid. By breathing in: no human blood-level data were found in the sources read.
Distribution: Detected in nasal polyp tissue after swallowing, which the authors take to show a spread through the body. Plasma concentrations of about 1.5 microgram/mL are cited in a review as the level used in lab cell tests.
Metabolism: Human liver CYP3A4 turns it into 2-exo-hydroxy-1,8-cineole (lab). No human metabolite data in people were found.
Elimination: No data found.
Bioavailability: Not established for any route or product, including capsules, vapour or cannabis.

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13benefits and uses looked at

46studies and sources checked

Moderate certaintybest evidence rating found

8lab markers tracked in trials

1 moderate certainty4 low certainty6 very low certainty2 not enough evidence

What was looked at

The 13 benefits and uses checked for Eucalyptol (1,8-Cineole), each with how strong the evidence is. Tap one to open it.

COPD flare-ups (cineole capsules as an add-on)Low certainty
Asthma control (cineole capsules as an add-on)Low certainty
Cutting oral steroid tablets in severe asthmaVery low certainty
Cough in acute bronchitisLow certainty
Acute sinus infection that is not yet pus-filledModerate certainty
Common cold (starting early)Very low certainty
Sinus surgery recovery and chronic sinusitis (a three-terpene mixture)Low certainty
Pain after knee replacement surgery (smelling eucalyptus oil)Very low certainty
Pain and inflammation tests in rats and miceVery low certainty
Inflammation signals in cellsVery low certainty
Cooling feeling and irritation sensors (lab)Very low certainty
Eucalyptol as a marker in a cannabis pain studyNot enough evidence
Cannabis extracts and cancer cells (a weak signal)Not enough evidence

Lab markers tracked in the studies

COPD flare-ups (exacerbations)Lung function (FEV1)Cough fitsSinus symptom sum scoreDaily dose of oral steroid tabletsPain score (visual analogue scale)NF-kappa-B activity in human cellsPain behaviour and paw swelling in rodents

What is Eucalyptol (1,8-Cineole) good for?

The uses people ask about and how strong the evidence is for each. For eucalyptol, the human trials are of cineole capsules for airway disease (mostly funded by the maker); everything else is lab, animal, or an association. The mixture rows are not eucalyptol alone.

COPD flare-ups (cineole capsules as an add-on)Low certaintyFewer COPD flare-ups with cineole capsules as an add-on, in one company-funded trial of 242 adults over 6 months. Asthma control (cineole capsules as an add-on)Low certaintyBetter lung function, symptoms and quality of life with cineole capsules in one trial of 247 adults; p-values near 0.05. Cutting oral steroid tablets in severe asthmaVery low certaintyA very small 2003 trial (32 adults): more people on cineole cut their steroid tablets than on placebo. Cough in acute bronchitisLow certaintyFewer cough fits after 4 days in one company-funded trial of 242 adults. Acute sinus infection that is not yet pus-filledModerate certaintyFaster fall in sinus symptoms in a 152-person trial; a 2023 network meta-analysis rated the evidence moderate. Common cold (starting early)Very low certaintyStarting a branded cineole capsule early went with a lighter, shorter cold in an open-label, company-funded trial with no placebo group. Sinus surgery recovery and chronic sinusitis (a three-terpene mixture)Low certaintyTwo trials of a three-terpene capsule (eucalyptol, limonene, pinene) with a steroid spray: one small gain, one missed main goal. Not eucalyptol alone. Pain after knee surgery (smelling eucalyptus oil)Very low certaintyLower pain scores after knee surgery when patients smelled eucalyptus oil rather than almond oil; whole oil, one trial, unblinded in practice. Pain and inflammation tests in rats and miceVery low certaintyRat and mouse tests show less pain behaviour and swelling at large doses, and a sleepy effect. No human data. Inflammation signals in cellsVery low certaintyIn human cells in dishes cineole lowered NF-kappa-B, an inflammation switch. Lab only. Cooling feeling and irritation sensors (lab)Very low certaintyIn cells it activates a cooling sensor (TRPM8) and blocks an irritation sensor (TRPA1). Lab and animal only. Eucalyptol as a marker in a cannabis pain studyNot enough evidenceA 2025 prediction model on 329 medical-cannabis patients named eucalyptol as a key predictor of pain relief; an association only. Cannabis extracts and cancer cells (a weak signal)Not enough evidenceEucalyptol content showed a weak, non-significant link to cancer-cell killing by cannabis extracts in dishes. Not a treatment.

Benefits, one by one

Each card is a research question, not a promise. Tap a goal to filter. Open a card to see the studies, doses and limits.

COPD flare-ups (cineole capsules as an add-on)

Low certainty

In one company-funded trial of 242 adults with stable COPD, cineole capsules taken for 6 months on top of usual treatment went with fewer, milder and shorter flare-ups than placebo. It is one trial, and it tested one cineole product.

3 studiesCineole capsules, 200 mg three times a day for 6 months, as given in …

Studies, doses and limits

What the trials found

One randomised, placebo-controlled trial in people (242 adults), plus a 2026 network meta-analysis that ranked cineole first for fewer flare-ups and fewer side effects among COPD mucolytic drugs.

Results

In the 6-month trial, flare-ups (frequency, severity and duration combined) were significantly lower than with placebo, and lung function, breathlessness and quality of life were better; adverse events were comparable. The 2026 network meta-analysis of 18 trials (4,408 people) ranked cineole top for fewer flare-ups and fewer adverse reactions (SUCRA 87.72% and 79.04%).

Effect sizes as reported

A review reports a 38.5% fall in flare-ups, quoting the same COPD trial. The abstract of the trial itself gives no number.

Why this rating

One trial of this exact kind, run by one research group and funded by the maker (Cassella-med). The network meta-analysis is an indirect ranking and may rest mostly on that same trial. No GRADE rating was given in either abstract.

Form and dose studied

Cineole capsules, 200 mg three times a day for 6 months, as given in the trial (product name not given in the abstract). Not eucalyptus oil.

Who was studied

Adults with stable COPD, winter-time, multi-centre.

Limits

Only one trial; funded by the maker; 6 months; it has not been confirmed by an independent group that we found. COPD is a serious illness and people should stay on the medicines their doctors prescribe.

Why researchers looked

Cineole is the main compound of eucalyptus oil and has been developed in Germany as a capsule for airway disease. A research group tested it in COPD, a long-term lung disease with sudden flare-ups.

Traditional use

Eucalyptus oil is a traditional medicine for cough with a cold (European herbal committee opinion). That is a use of the oil, not a test of cineole alone.

Proposed mechanism Mixed

In cells and in animals cineole lowers inflammation signals such as NF-kappa-B and cytokines, and in human liver tissue it is broken down mostly by CYP3A4. None of this proves how it works in a person.

A proposed mechanism does not show that the effect happens in people.

Cineole capsules are a different thing from eucalyptus oil. Swallowing the oil itself has caused seizures and coma in children (see the Safety tab). Ask a doctor or pharmacist before using any cineole product, especially in children, in pregnancy, or with steroid tablets.

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Asthma control (cineole capsules as an add-on)

Low certainty

In one trial of 247 adults with asthma, cineole capsules for 6 months went with better lung function, fewer symptoms and better quality of life than placebo. The trial is from the same research group as the COPD trial.

2 studiesCineole capsules, 200 mg three times a day for 6 months, as given in …

Studies, doses and limits

What the trials found

One randomised, placebo-controlled trial (247 adults).

Results

On a combined measure the cineole group improved more than placebo (p = 0.0027). The single measures were also significant but only just: lung function (FEV1) p = 0.0398, symptoms p = 0.0325, quality of life p = 0.0475.

Effect sizes as reported

The abstract gives p-values only, with no sizes of change.

Why this rating

A single trial with p-values near 0.05 on the single measures, no effect sizes in the abstract and unclear funding in the abstract.

Form and dose studied

Cineole capsules, 200 mg three times a day for 6 months, as given in the trial (product name not given in the abstract).

Who was studied

Adults with confirmed asthma; multi-centre.

Limits

One trial. The abstract does not give sizes, funding or any independent repeat. Asthma needs its prescribed treatment.

Why researchers looked

Based on the COPD results, the same group tested cineole as an add-on in asthma.

Traditional use

Eucalyptus oil is a traditional medicine for cough with a cold (European herbal committee opinion). That is a use of the oil, not a test of cineole alone.

Proposed mechanism Mixed

A proposed mechanism does not show that the effect happens in people.

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Cutting oral steroid tablets in severe asthma

Very low certainty

A very small early trial (32 adults) found that more people on cineole capsules managed to reduce their steroid tablets than on placebo. It is a small study from 2003 and has not been shown again at that size.

1 studiesCineole capsules, 200 mg three times a day for 12 weeks, as given in …

Studies, doses and limits

What the trials found

One small randomised, placebo-controlled trial (32 adults).

Results

Steroid doses fell by 36% on cineole and by 7% on placebo (p = 0.006); 12 of 16 versus 4 of 16 managed a reduction (p = 0.012), over 12 weeks.

Effect sizes as reported

Mean fall of 3.75 mg of prednisolone a day with cineole against 0.91 mg with placebo.

Why this rating

Only 32 people; one trial; funding not stated in the abstract; no repeat found.

Form and dose studied

Cineole capsules, 200 mg three times a day for 12 weeks, as given in the trial.

Who was studied

Adults with steroid-dependent severe asthma.

Limits

Very small. Never change steroid tablets without your doctor: the trial team tapered doses under supervision.

Why researchers looked

Steroid tablets for severe asthma have many side effects, so the 2003 trial asked whether cineole could allow a lower dose.

Proposed mechanism Laboratory research

Cineole lowers inflammation signals in cells (NF-kappa-B and cytokines).

A proposed mechanism does not show that the effect happens in people.

¹⁵

Cough in acute bronchitis

Low certainty

In 242 adults with acute bronchitis, cineole capsules for 10 days went with fewer cough fits after 4 days than placebo. Acute bronchitis usually gets better by itself.

1 studiesCineole capsules, 200 mg three times a day for 10 days, as given in t…

Studies, doses and limits

What the trials found

One randomised, placebo-controlled trial funded by the maker.

Results

After 4 days the cineole group had improved more on the Bronchitis Sum Score (p = 0.0383), with fewer cough fits (p = 0.0001).

Effect sizes as reported

The abstract gives p-values only.

Why this rating

One trial funded by the maker (Cassella-med). The overall score difference is just under the usual 0.05 cut-off.

Form and dose studied

Cineole capsules, 200 mg three times a day for 10 days, as given in the trial.

Who was studied

Adults with confirmed acute bronchitis.

Limits

The abstract does not report recovery after day 4 or how many people needed antibiotics. A cough with fever, blood, or breathing trouble needs a doctor.

Why researchers looked

Cineole is used as a mucus-loosening medicine for coughs and chest colds.

Traditional use

Eucalyptus oil is a traditional medicine for cough with a cold (European herbal committee opinion). That is a use of the oil, not a test of cineole alone.

Proposed mechanism Mixed

A proposed mechanism does not show that the effect happens in people.

⁵

Acute sinus infection that is not yet pus-filled

Moderate certainty

One trial of 152 adults found cineole capsules gave a faster fall in sinus symptoms over 7 days than placebo. A 2023 network meta-analysis of herbal medicines for sinus problems ranked cineole among the best for acute post-viral sinusitis, with moderate certainty.

2 studiesCineole capsules, two 100 mg capsules three times a day for 7 days, a…

Studies, doses and limits

What the trials found

One placebo-controlled trial (152 adults) and a 2023 network meta-analysis of 47 trials of herbal medicines, which rated its evidence for acute post-viral rhinosinusitis as moderate certainty (GRADE).

Results

Symptom score fell from 15.6 to 3.0 on cineole and to 9.2 on placebo by day 7 (6.9 against 12.2 on day 4). Two people on cineole had heartburn or a rash. The meta-analysis put Cineole and Pelargonium sidoides top for symptom control.

Effect sizes as reported

Differences of 6 points or more in the score on day 7; abstracts give no confidence intervals.

Why this rating

The network meta-analysis authors graded the evidence as moderate for this condition. It rests on few trials and the 2004 trial's funding is not stated in the abstract.

Form and dose studied

Cineole capsules, two 100 mg capsules three times a day for 7 days, as given in the trial.

Who was studied

Adults with acute non-pus rhinosinusitis.

Limits

A short trial. Many sinus infections clear on their own, and a sinus infection with fever, facial swelling or eye symptoms needs a doctor.

Why researchers looked

Cineole is sold in some countries as a capsule for blocked sinuses.

Traditional use

Eucalyptus oil is a traditional medicine for cough with a cold (European herbal committee opinion). That is a use of the oil, not a test of cineole alone.

Proposed mechanism Mixed

A proposed mechanism does not show that the effect happens in people.

^{18 9}

Common cold (starting early)

Very low certainty

A company-funded, open-label trial of a branded cineole capsule found that people who started it earlier in their cold had a lighter and shorter illness. With no placebo group, it cannot show the capsule works.

1 studiesSoledum (CNL-1976) 200 mg capsules three times a day, as given in the…

Studies, doses and limits

What the trials found

One open-label, non-randomised, exploratory trial (329 people who developed a cold), funded by the maker.

Results

People who started within 12 hours had a 38% lower overall burden of illness (p < 0.0001) and a shorter time to remission (8.9 against 10.7 days with the latest start, p < 0.05). 4.3% reported side effects judged possibly related.

Effect sizes as reported

38% lower burden of illness with the earliest start; 1.8 days shorter to remission.

Why this rating

No placebo and no randomisation, industry funded. The comparison is between people who started at different times, who may differ.

Form and dose studied

Soledum (CNL-1976) 200 mg capsules three times a day, as given in the trial. This is a branded product.

Who was studied

Adults who developed a common cold.

Limits

Cannot separate the effect of the capsule from the natural course of a cold. Exploratory trial.

Why researchers looked

Colds peak in two days, so the trial enrolled people before they were ill and watched when they started the capsule.

Traditional use

Eucalyptus oil is a traditional medicine for cough with a cold (European herbal committee opinion). That is a use of the oil, not a test of cineole alone.

Proposed mechanism Mixed

A proposed mechanism does not show that the effect happens in people.

²⁴

Sinus surgery recovery and chronic sinusitis (a three-terpene mixture)

Low certainty

Two Chinese trials tested capsules of eucalyptol, limonene and pinene together with a steroid nose spray. One (174 people) found slightly better scan and endoscopy scores. The other (291 people) missed its main goal at week 8.

2 studiesEucalyptol + limonene + pinene enteric capsules (ELP) with a steroid …

Studies, doses and limits

What the trials found

Two randomised trials of the same type of mixture capsule (465 people in all), neither testing eucalyptol alone.

Results

Trial 1 (174 people after sinus surgery for nasal polyps): capsule plus steroid spray beat spray alone on Lund-Mackay (p = 0.029) and Lund-Kennedy (p = 0.025) scores; side effects did not differ. Trial 2 (291 people with chronic sinusitis, double-blind): the week-8 main goal was not met (p = 0.093) although week 4 was (p = 0.012), and the scan and VAS scores did not differ at week 8.

Effect sizes as reported

Only p-values and group means in the abstracts; trial 2 improvement 4.37 against 3.85 points at week 8.

Why this rating

The week-8 main goal in the double-blind trial was missed, and the other trial did not state blinding. The mixture means the result cannot be given to eucalyptol alone.

Form and dose studied

Eucalyptol + limonene + pinene enteric capsules (ELP) with a steroid nose spray, as given in the trials. A three-terpene mixture, not eucalyptol alone.

Who was studied

Adults with chronic sinusitis; some after sinus surgery for nasal polyps.

Limits

Mixture of three terpenes. Many outcomes were tested, and some single improvements may be chance.

Why researchers looked

A mixture of eucalyptol, limonene and pinene is used in some countries as a mucus-clearing capsule for sinus disease.

Proposed mechanism Mixed

Not established; the trials looked at scans, symptoms and nasal inflammation markers.

A proposed mechanism does not show that the effect happens in people.

^{35 12}

Pain after knee replacement surgery (smelling eucalyptus oil)

Very low certainty

One small trial found that smelling eucalyptus oil for 30 minutes on three days went with lower pain scores than smelling almond oil. It is a whole oil, not cineole alone, and a correction notice was published in 2026.

1 studiesEucalyptus oil, inhaled for 30 minutes during knee movement exercise.…

Studies, doses and limits

What the trials found

One randomised trial (number of people not given in the abstract).

Results

Pain scores were lower with eucalyptus oil than almond oil on all three days (p < .001); systolic and diastolic blood pressure were lower on day 2; heart rate, CRP and white cell count did not differ.

Effect sizes as reported

The abstract gives no numbers for pain change.

Why this rating

One trial, probably unblinded in practice because the oils smell different, with self-rated pain, no numbers in the abstract and a 2026 correction notice we did not read.

Form and dose studied

Eucalyptus oil, inhaled for 30 minutes during knee movement exercise. A whole essential oil.

Who was studied

Adults after total knee replacement.

Limits

The comparison oil smells different. Not a test of cineole, and not a pain treatment recommendation. Never swallow the oil or let small children reach it.

Why researchers looked

Eucalyptus oil is a folk remedy for aches and pains, and nurses have used scents as a simple comfort.

Traditional use

Eucalyptus oil is used traditionally for localised muscle pain; the EU herbal committee lists this as a traditional use based on long use only.

Proposed mechanism Lab and animal

Not tested in this trial. In cells and animals cineole acts on cool and irritation sensors (TRPM8 and TRPA1).

A proposed mechanism does not show that the effect happens in people.

Never give essential oil to children to swallow or inhale without medical advice; the EU herbal committee says it must not be used under 24 months.

¹⁷

Pain and inflammation tests in rats and mice

Very low certainty

In rats and mice, cineole reduced pain behaviour and paw swelling, did not seem to work through opioid receptors in one test, and made mice less active and more sleepy. This is animal work at large doses.

2 studiesPure cineole by mouth or by injection in lab doses. Not a scent and n…

Studies, doses and limits

What the trials found

No human trial.

Results

In rats, cineole reduced swelling in the carrageenan paw test and the cotton-pellet granuloma test. In mice it reduced chemical pain behaviour in the formalin and acetic acid tests at 100 to 400 mg/kg by mouth, reduced movement and lengthened pentobarbital sleeping time. A second paper reported pain-test effects 'comparable to morphine' in the tail-flick and hot-plate tests, with no block by naloxone.

Effect sizes as reported

Oral doses of 100 to 400 mg/kg in the first paper.

Why this rating

Animal only, with large doses and short tests.

Form and dose studied

Pure cineole by mouth or by injection in lab doses. Not a scent and not a cannabis flower.

Who was studied

Mice and rats.

Limits

Animal pain tests do not predict pain relief in people. The sedating effect in mice is also a safety signal.

Why researchers looked

Researchers test plant compounds in rodent pain and swelling tests before any human study.

Proposed mechanism Animal research

In mice the pain effect was not blocked by naloxone, so it does not appear to use opioid receptors; in cells it acts on the TRPA1 and TRPM8 sensors.

A proposed mechanism does not show that the effect happens in people.

The sleepiness effect in mice is one reason to take care with sedatives and alcohol.

^{33 20}

Inflammation signals in cells

Very low certainty

In human cells in dishes, cineole lowered the activity of NF-kappa-B, a master switch for inflammation, by keeping part of it out of the nucleus. This is a possible lab explanation for the respiratory trial results, not proof of effect.

1 studiesPure 1,8-cineol added to cells. Not a capsule, oil or vapour.

Studies, doses and limits

What the trials found

No human data on this mechanism.

Results

Cineole lowered NF-kappa-B activity in cells stimulated with a bacterial toxin and lowered its target genes; in human blood cells, nuclear p65 was reduced.

Effect sizes as reported

No concentrations are given in the abstract.

Why this rating

Cells in dishes.

Form and dose studied

Pure 1,8-cineol added to cells. Not a capsule, oil or vapour.

Who was studied

Human cell lines and human blood cells.

Limits

A dish result may not happen in a body.

Why researchers looked

The trials in lung disease raised the question of how cineole lowers inflammation.

Proposed mechanism Laboratory research

In human cell lines (U373, HeLa) and human blood cells, 1,8-cineol reduced NF-kappa-B movement into the nucleus and the activity of its target genes.

A proposed mechanism does not show that the effect happens in people.

None specific.

⁷

Cooling feeling and irritation sensors (lab)

Very low certainty

In cells, cineole switches on the cold-sensing TRPM8 channel and blocks the pain and irritation sensor TRPA1. This may explain why eucalyptus feels cool and why it can reduce irritation in animal tests.

1 studiesPure compound in lab tests.

Studies, doses and limits

What the trials found

No human data.

Results

1,8-cineole produced currents in cells with human TRPM8 and blocked human TRPA1 currents set off by several triggers; in animals, it reduced sensory irritation produced by octanol and menthol.

Effect sizes as reported

Not given in the abstract.

Why this rating

Cells and animals. The authors call it a possible analgesic, not a proven one.

Form and dose studied

Pure compound in lab tests.

Who was studied

Cells and animals.

Limits

Not a pain trial in people.

Why researchers looked

A search for natural compounds that cool and soothe without irritating led researchers to cineole.

Proposed mechanism Lab and animal

Activates human TRPM8 and blocks human TRPA1 in cells; reduced sensory irritation from two TRPA1 triggers in animals. The close relative 1,4-cineole activated both channels.

A proposed mechanism does not show that the effect happens in people.

None specific.

³⁷

Eucalyptol as a marker in a cannabis pain study

Not enough evidence

A 2025 computer analysis of 329 chronic-pain patients on medical cannabis found that eucalyptol (and alpha-bisabolol) helped to predict who got pain relief. This is an association, and the model was only a little better than chance.

1 studiesMedical cannabis flower of different cultivars, as prescribed in Isra…

Studies, doses and limits

What the trials found

One observational study with machine learning (329 people).

Results

Adding the chemical profile improved prediction of pain relief (AUC 0.63 against 0.52 without it). THC and CBD had limited predictive value, and the terpenoids alpha-bisabolol and eucalyptol were key predictors. The abstract does not say if more eucalyptol went with more or less relief.

Effect sizes as reported

AUC 0.63 compared with 0.52.

Why this rating

An association from a prediction model, little above chance (0.5), without a stated direction for eucalyptol and without a control group.

Form and dose studied

Medical cannabis flower of different cultivars, as prescribed in Israel. Not isolated eucalyptol.

Who was studied

Adults with chronic pain on medical cannabis.

Limits

Cannot show that eucalyptol relieves pain. Eucalyptol amount may stand in for other features of the flower.

Why researchers looked

Researchers asked whether the chemical profile of cannabis flower, beyond THC and CBD, explains pain relief.

Proposed mechanism None

Not tested. The authors suggest compound-specific effects; the study cannot show that eucalyptol causes pain relief.

A proposed mechanism does not show that the effect happens in people.

Cannabis carries THC risks (impairment, anxiety, dependence) whatever its terpenes.

⁸

Cannabis extracts and cancer cells (a weak signal)

Not enough evidence

In dishes, eucalyptol content in 25 high-THC cannabis extracts showed a weak, non-significant link to killing cancer cells. It is not a cancer treatment.

1 studiesWhole high-THC cannabis extracts, not isolated eucalyptol.

Studies, doses and limits

What the trials found

No human data.

Results

Extracts slowed squamous cell cancer growth by 66% to 92%. Terpinene correlated with that effect (p = 0.002); eucalyptol came second with p = 0.094, which is above the usual 0.05 cut-off.

Effect sizes as reported

Correlation p = 0.094 for eucalyptol.

Why this rating

A correlation that is not significant, using whole extracts in cell dishes.

Form and dose studied

Whole high-THC cannabis extracts, not isolated eucalyptol.

Who was studied

Cancer cell line and fibroblasts in dishes.

Limits

Not a cancer treatment; do not use cannabis in place of cancer care.

Why researchers looked

Researchers tested whether terpene content explains why some extracts hit cancer cells harder.

Proposed mechanism Laboratory research

Not tested; the authors say terpenes may modulate cannabinoid activity.

A proposed mechanism does not show that the effect happens in people.

None specific.

¹⁹

Connections to the rest of health

How Eucalyptol (1,8-Cineole) connects to the rest of our health knowledge graph. Every link says what kind of connection it is. A safety link (for example to the liver) is a warning, not a benefit. A study that merely mentions a topic never creates a benefit link.

Explore every connection: goals, body systems, organs, symptoms, genes

Kind of connection Connected to Search

B. Body systems

Connected to	Kind of connection	Evidence status	Context	Studies
Nervous system	Adverse effect or risk	Low certainty	Seizures and drowsiness are reported in children and adults, from case series. Preparation or compound: Eucalyptus oil swallowed or breathed in	^{32 29 39}
Respiratory System	Biological association	Low certainty	Studied for: COPD flare-ups (cineole capsules as an add-on) Studied for: Asthma control (cineole capsules as an add-on)	^{41 43 16 42 15 5 18 9 24 35 12}
Immune System	Biological association	Very low certainty	Studied for: Cutting oral steroid tablets in severe asthma Studied for: Common cold (starting early)	^{15 24 33 20 7 19}
Nervous System	Biological association	Very low certainty	Studied for: Pain after knee replacement surgery (smelling eucalyptus oil) Studied for: Pain and inflammation tests in rats and mice	^{17 33 20 37 8}

C. Body parts and organs

Connected to	Kind of connection	Evidence status	Context	Studies
Skin	Adverse effect or risk	Low certainty	Allergic skin reactions and contact eczema are listed. Preparation or compound: Pure cineole and eucalyptus oil	^{26 4}

I. Biomarkers

Connected to	Kind of connection	Evidence status	Context	Studies
COPD flare-ups (exacerbations)	Biological association	Low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{41 43}
Lung function (FEV1)	Biological association	Low certainty	Measured in trials: improved. A lab change is not the same as a health benefit.	^{42 41}
Cough fits	Biological association	Low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	⁵
Sinus symptom sum score	Biological association	Moderate certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{18 9}
Daily dose of oral steroid tablets	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	¹⁵
Pain score (visual analogue scale)	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	¹⁷
NF-kappa-B activity in human cells	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	⁷
Pain behaviour and paw swelling in rodents	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{33 20}

L. Active compounds

Connected to	Kind of connection	Evidence status	Context	Studies
1,8-cineole (eucalyptol)	Biological association	Human (capsules)	Tested in people as capsules for airway disease; lab and animal work on inflammation and pain sensors. Preparation or compound: Leaf essential oils of eucalyptus, bay laurel, rosemary, sage and some tea tree types	^{41 7}
2-exo-hydroxy-1,8-cineole	Biological association	In vitro	The main product of cineole oxidation by human liver CYP3A4 in lab tests.	²⁵
alpha-Pinene and limonene	Biological association	Human (mixture)	Combined with eucalyptol in the three-terpene capsules (ELP) tested in sinus trials. See the limonene and pinene pages. Preparation or compound: Found with cineole in eucalyptus oil (7.3% and 6.9% in one oil) and rosemary oil (alpha-pinene 20.14%)	^{46 14 12}
Terpinen-4-ol	Biological association	Not assessed	Not studied here; named only to show which tea tree type is meant. Preparation or compound: Tea tree oil; one oil type is dominated by it, while others are dominated by cineole	¹¹
Thujones and camphor	Biological association	Plant analysis	A sage oil abstract calls thujones toxic and notes high levels in Estonian sage. Preparation or compound: Sage oil, next to cineole	³¹

Each connection is stored with the ingredient, the connected record, the kind of connection, the evidence status, the supporting studies, the preparation or compound involved, and a review date (last reviewed October 25, 2026).

Evidence at a glance: what changed in 7 lab markers

Tap a number to show only those markers. Counts are markers, not people.

Other7

The evidence

The research centre for Eucalyptol (1,8-Cineole). Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.

Evidence by outcome

COPD flare-ups (cineole capsules as an add-on) 3 studies · 242 people in trials Low certainty Asthma control (cineole capsules as an add-on) 2 studies · 247 people in trials Low certainty Cutting oral steroid tablets in severe asthma 1 study · 32 people in trials Very low certainty Cough in acute bronchitis 1 study · 242 people in trials Low certainty Acute sinus infection that is not yet pus-filled 2 studies · 152 people in trials Moderate certainty Common cold (starting early) 1 study Very low certainty Sinus surgery recovery and chronic sinusitis (a three-terpene mixture) 2 studies · 465 people in trials Low certainty Pain after knee replacement surgery (smelling eucalyptus oil) 1 study Very low certainty Pain and inflammation tests in rats and mice 2 studies Very low certainty Inflammation signals in cells 1 study Very low certainty Cooling feeling and irritation sensors (lab) 1 study Very low certainty Eucalyptol as a marker in a cannabis pain study 1 study Not enough evidence Cannabis extracts and cancer cells (a weak signal) 1 study Not enough evidence

Bars show how many studies we found for each outcome, not how well it works. People are added up across trials only (reviews are not added, to avoid double counting).

How we rate evidence

High certainty

Several well-run trials or reviews agree; further research is unlikely to change the picture much.

Moderate certainty

Good trials point the same way, but some doubt remains.

Low certainty

Small, short or inconsistent trials. The finding could change with better research.

Very low certainty

Very little or very weak human data. Treat as a possibility only.

Mixed findings

Trials or reviews disagree with each other.

Not enough evidence

Not enough human research to say either way.

Evidence against

Good research found no benefit, or found harm.

We take the reviewers' own risk-of-bias and GRADE statements where they exist, and otherwise judge from study size, design, consistency, directness and whether a product matches what is sold. Many publications do not make evidence high. Method note: We searched PubMed and read the abstracts of about 36 papers, read the EU herbal monograph on eucalyptus oil in full, read the US food-flavouring list through the eCFR, read PubChem for identity and hazard notifications, and read hospital and health-department guidance on eucalyptus oil poisoning through a page reader. We read two trial funding statements in full text. We say which sources we could not read.

Study library: every study we checked 46

Design Research type Year from Search

Study	Design	People	Product, dose, length	Result
Cal 2008 Ex vivo skin absorption of terpenes from Vicks VapoRub ointment. Med Sci Monit · PMID 18668006	Laboratory research human cadaver skin	Human cadaver skin in a diffusion chamber	Vicks VapoRub ointment (eucalyptol, menthol, camphor, alpha-pinene, beta-pinene) Branded ointment Applied for 15, 30 and 60 minutes Minutes	The terpenes did not pass through the skin into the receiving fluid in this set-up. Eucalyptol built up most in the stratum corneum and in the deeper skin. The authors say the terpenes could easily enter the blood circulation in living people. Eucalyptol enters skin readily from a rub Methods, limits and funding Outcomes: How much of each terpene entered the skin layers Limitations: Skin from dead donors in a lab device. The conclusion about blood is the authors' guess, not a measurement. Funding and conflicts: Not stated in the abstract. Read: abstract
Caputo 2017 Laurus nobilis: Composition of Essential Oil and Its Biological Activities. Molecules · PMID 28587201 · DOI	Chemical analysis plant oil	Bay laurel (Laurus nobilis) leaf oil, southern Italy	Laurus nobilis leaf essential oil Leaf oil	1,8-cineole was the main component at 31.9%, followed by sabinene (12.2%) and linalool (10.2%). 55 compounds made up 91.6% of the oil. Cineole is the largest compound (31.9%) in this bay laurel leaf oil Methods, limits and funding Outcomes: Composition by GC and GC/MS Limitations: One oil from one region. Funding and conflicts: The authors declare no conflict of interest. Read: abstract
Day 1997 Eucalyptus oil poisoning among young children: mechanisms of access and the potential for prevention. Aust N Z J Public Health · PMID 9270157 · DOI	Survey	109 Parents of children under 5 with actual or suspected eucalyptus oil swallowing, Victoria, Australia	Eucalyptus oil products (vaporiser solutions, oil preparations) Essential oil products 9-month survey	Eucalyptus oil was a leading agent in hospitalisation for poisoning of under-5s in Victoria. In the survey, 90 incidents involved vaporiser solutions, 15 eucalyptus oil preparations and the rest other medicinal products; 74% got to the oil through a home vaporiser, most often at floor level. The authors say amounts swallowed are usually small but the reported toxic dose range is wide, so a medical check is needed after swallowing. Home vaporiser solutions were the way most toddlers got to eucalyptus oil Methods, limits and funding Outcomes: How children reached the oil; how common the problem was Limitations: Victoria in the 1990s. Rules and products have changed since. Funding and conflicts: Not stated in the abstract. Read: abstract
European Medicines Agency 2024 European Union herbal monograph on Eucalyptus globulus Labill.; Eucalyptus polybractea R.T. Baker; Eucalyptus smithii R.T. Baker, aetheroleum (EMA/HMPC/320292/2023, Final, Revision 1) EMA (adopted 20 November 2024; PDF read 2026-10-25) · Source	Authoritative guidance n/a	n/a	n/a	Traditional-use medicine for cough with a cold and for localised muscle pain, "exclusively based upon long-standing use". Contraindicated: sensitivity to eucalyptus oil or 1,8-cineol, children with a history of seizures (febrile or not), and children under 24 months, because 1,8-cineole preparations, like other essential oils, can induce laryngospasm. Oral use in children under 12 and inhalation under 3 years: use not established for lack of data. Pregnancy and lactation: not recommended for lack of data. Effects listed: allergic reactions (including severe), stomach upset (oral), contact eczema (skin); frequency unknown. Interactions: none reported. Overdose: stomach symptoms, breathing problems, CNS depression, loss of consciousness, convulsions, ataxia. Adequate tests on reproductive toxicity, genotoxicity and carcinogenicity have not been performed. It says nothing about cannabis products. Traditional-use medicine for cough with a cold and for localised muscle pain, "exclusively based upon long-standing use". Contraindicated: sensitivity to eucalyptus oil or 1,8-cineol, children with a history of seizures (febrile or not), and children under 24 months, because 1,8-cineole preparations, like other essential oils, can induce laryngospasm. Oral use in children under 12 and inhalation under 3 years: use not established for lack of data. Pregnancy and lactation: not recommended for lack of data. Effects listed: allergic reactions (including severe), stomach upset (oral), contact eczema (skin); frequency unknown. Interactions: none reported. Overdose: stomach symptoms, breathing problems, CNS depression, loss of consciousness, convulsions, ataxia. Adequate tests on reproductive toxicity, genotoxicity and carcinogenicity have not been performed. It says nothing about cannabis products. Methods, limits and funding Outcomes: What the EU herbal committee says about eucalyptus oil medicines Limitations: A traditional herbal medicine opinion based on long use, not on trials. It covers eucalyptus oil, not isolated cineole capsules. It does not apply to products sold as food supplements or cosmetics. Funding and conflicts: n/a Read: full-text
Fischer 2013 Efficacy of cineole in patients suffering from acute bronchitis: a placebo-controlled double-blind trial. Cough · PMID 24261680 · DOI	Controlled trial	242 Adults with confirmed acute bronchitis (multi-centre)	Cineole capsules (the product name is not given in the abstract) Isolated compound (1,8-cineole) in capsules 200 mg three times a day, as given in the trial 10 days · vs Placebo capsules	After 4 days the cineole group had improved more on the Bronchitis Sum Score (p = 0.0383), and cough fits were fewer (p = 0.0001). Registered as ISRCTN37784439. Fewer cough fits after 4 days than with placebo Methods, limits and funding Outcomes: Bronchitis Sum Score (cough and related symptoms) Limitations: The overall score gain is only just below p = 0.05. Acute bronchitis usually gets better by itself, and the abstract does not show how fast the placebo group recovered after day 4. Funding and conflicts: Funded by a grant from Cassella-med, Cologne, Germany, the maker of cineole products (read in the full text on Europe PMC). The authors declare no competing interests. Registration: ISRCTN37784439 Read: abstract and full text (funding statement)
Government of Western Australia 2026 Essential oils: safety and first aid (Healthy WA) Healthy WA (read 2026-10-25; page shows no review date) · Source	Authoritative guidance n/a	n/a	n/a	Says eucalyptus oil, clove oil, tea tree oil and aromatherapy oils are commonly used essential oils; children are particularly susceptible; as little as 2 mL (less than half a teaspoon) of eucalyptus oil can cause significant poisoning in an infant; essential oils are not safe to consume. First aid: do not induce vomiting; call the Poisons Information Centre on 13 11 26. Says eucalyptus oil, clove oil, tea tree oil and aromatherapy oils are commonly used essential oils; children are particularly susceptible; as little as 2 mL (less than half a teaspoon) of eucalyptus oil can cause significant poisoning in an infant; essential oils are not safe to consume. First aid: do not induce vomiting; call the Poisons Information Centre on 13 11 26. Methods, limits and funding Outcomes: What a state health department tells the public about swallowed essential oils Limitations: A public advice page, not a study. The page shows no review date. Funding and conflicts: n/a Read: summary-only
Greiner 2013 1,8-Cineol inhibits nuclear translocation of NF-κB p65 and NF-κB-dependent transcriptional activity. Biochim Biophys Acta · PMID 23872422 · DOI	Laboratory research cells	Human cell lines (U373, HeLa) and human blood cells	1,8-cineol Isolated compound Not given in the abstract · vs Untreated cells	1,8-cineol lowered NF-kappa-B activity in cells stimulated with a bacterial toxin (LPS) and reduced movement of the p65 protein into the nucleus. It also lowered NF-kappa-B target gene activity and, in human blood cells, nuclear p65. The abstract describes Soledum as the clinically approved drug that contains the compound. A lab explanation for an anti-inflammatory effect Methods, limits and funding Outcomes: NF-kappa-B activity and movement into the nucleus; target gene expression Limitations: Cells in dishes. It does not show the same happens in a person who takes a capsule or breathes vapour. Funding and conflicts: Not stated in the abstract. Read: abstract
Hatav 2025 Machine-learning of medical cannabis chemical profiles reveals analgesia beyond placebo expectations. Commun Med (Lond) · PMID 40670615 · DOI	Observational	329 Adults with chronic pain prescribed medical cannabis in Israel	Medical cannabis flower of different chemical profiles (about 200 compounds measured) Cannabis flower Not given in the abstract Prospective study	Adding the chemical profile improved the prediction of pain relief (AUC 0.63) over a model without it (AUC 0.52). The authors report that THC and CBD had limited predictive value and that the terpenoids alpha-bisabolol and eucalyptol were key predictors. The abstract does not say whether eucalyptol went with more or less relief. Eucalyptol was one of the compounds that helped predict pain relief; the direction is not given in the abstract Methods, limits and funding Outcomes: Whether the chemical profile of the cannabis predicted pain relief Limitations: An association from a computer model, with an AUC (0.63) only a little above chance (0.5). It does not show that eucalyptol relieves pain. People got whole cannabis products, so it could be a marker for other things. Funding and conflicts: One author consults for Link Cell Therapies; the others declare none. Read: abstract
Hoang 2023 Herbal Medicines for Rhinosinusitis: A Systematic Review and Network Meta-analysis. Curr Allergy Asthma Rep · PMID 36609950 · DOI	Network meta analysis	Adults and children with different forms of rhinosinusitis; 47 randomised trials of 18 herbal medicines	Several herbal medicines, including a cineole product ("Cineole") Various · vs Placebo or other treatment	For acute post-viral rhinosinusitis, Cineole and Pelargonium sidoides were the most effective treatments for controlling symptoms (moderate certainty). The authors say more trials with enough people and long follow-up are needed. Cineole ranked among the best of the herbal medicines tested for acute post-viral rhinosinusitis, with moderate certainty Methods, limits and funding Outcomes: Symptom scores and quality of life, graded for certainty (GRADE) Limitations: The abstract does not say how many cineole trials fed this result. Network comparisons rank treatments indirectly. Funding and conflicts: Not stated in the abstract. Read: abstract
Hoch 2023 1,8-cineole (eucalyptol): A versatile phytochemical with therapeutic applications across multiple diseases. Biomed Pharmacother · PMID 37696087 · DOI	Narrative review human and lab	Review of cineole across diseases	1,8-cineole (eucalyptol) Isolated compound	Says clinical trials in COPD, asthma, bronchitis and rhinosinusitis show benefit, and that uses in depression, epilepsy, ulcers, diarrhoea, heart disease and diabetes are potential only. Calls for study of safety and better formulations. Review; the non-respiratory uses are not shown in people Methods, limits and funding Outcomes: Summary of clinical trials and lab data Limitations: A review by authors with one employee of the cineole maker Cassella-med, who "provided guidance during the writing" (stated in the paper). Funding and conflicts: One author is employed by Cassella-med GmbH (maker of a cineole product). The others report no conflicts. Read: abstract
Homer 2000 Natural variation in the essential oil content of Melaleuca alternifolia Cheel (Myrtaceae). Biochem Syst Ecol · PMID 10725593 · DOI	Chemical analysis plant oil	Natural populations of tea tree (Melaleuca alternifolia), 615 trees	Tea tree leaf oil Leaf oil	Six chemotypes were found. One is dominated by terpinen-4-ol, one by 1,8-cineole, one by terpinolene, and three others by 1,8-cineole with differing terpinen-4-ol or terpinolene. High-cineole types dominated near Grafton, New South Wales. No percentages are in the abstract. Some tea tree trees make a cineole-rich oil; another type is dominated by terpinen-4-ol Methods, limits and funding Outcomes: Oil chemotypes Limitations: Wild trees in one country. It does not give the cineole content of tea tree oil sold in shops. Funding and conflicts: Not stated in the abstract. Read: abstract
Hu 2025 Efficacy and safety of intranasal corticosteroids combined with mucoactive drugs for chronic rhinosinusitis. Int Immunopharmacol · PMID 40911992 · DOI	Controlled trial	291 Adults with chronic rhinosinusitis (13 hospitals in China)	Eucalyptol + limonene + pinene enteric capsules (ELP) plus budesonide nose spray Mixture of three isolated terpenes in enteric capsules 0.8 g a day of the capsules, as given in the trial 8 weeks (visits at weeks 4 and 8) · vs Placebo capsules plus the same budesonide nose spray (double-blind)	The capsule group improved more at week 4 (p = 0.012), but at week 8, the planned main point, the difference was not significant (p = 0.093). The Lund-Mackay scan score and the VAS scale did not differ at week 8. Some single symptoms did improve more (nasal congestion, postnasal drip, runny nose, loss of smell). The effect on CT score was seen in smokers (p = 0.022). The main goal at week 8 was not met; some single symptoms and a smokers subgroup improved Methods, limits and funding Outcomes: Major Symptom Score change from the start to week 8 (the main goal); other symptoms; scans Limitations: A near-miss on the main goal, with many extra tests afterwards, so the positive findings are less secure. A three-terpene mixture, not eucalyptol alone. Funding and conflicts: The authors declare no competing financial interests. Read: abstract
Ittyachen 2019 Eucalyptus oil poisoning: two case reports. J Med Case Rep · PMID 31685016 · DOI	Case report	2 Two adult men who accidentally swallowed eucalyptus oil (India)	Eucalyptus oil swallowed Essential oil Not given in the abstract Admitted for 4 days	Both came in with seizures and severe metabolic acidosis, were treated in intensive care with bicarbonate and supportive care, and left hospital on day 4. The authors say seizures are unusual in adults but are not rare in children, and call for warning labels on all eucalyptus oil products. Seizures and acid-base upset in adults who swallowed the oil, with recovery Methods, limits and funding Outcomes: Symptoms and recovery Limitations: Two cases only. Funding and conflicts: No competing interests declared. Read: abstract
Jiang 2011 Chemical composition and antimicrobial activity of the essential oil of Rosemary. Environ Toxicol Pharmacol · PMID 21787731 · DOI	Chemical analysis plant oil	One rosemary essential oil	Rosemary essential oil Aerial parts	1,8-cineole (26.54%) and alpha-pinene (20.14%) were the major compounds out of 22 identified (97.41% of the oil). Cineole is the largest compound (26.54%) in this rosemary oil Methods, limits and funding Outcomes: Composition by GC-MS Limitations: One oil sample; rosemary oil varies a lot by type and place. Funding and conflicts: Not stated in the abstract. Read: abstract
Juergens 2003 Anti-inflammatory activity of 1.8-cineol (eucalyptol) in bronchial asthma: a double-blind placebo-controlled trial. Respir Med · PMID 12645832 · DOI	Controlled trial	32 Adults with steroid-dependent severe asthma	Cineole capsules (the product name is not given in the abstract) Isolated compound (1,8-cineole) in small gut-soluble capsules 200 mg three times a day, as given in the trial 12 weeks (after a 2-month run-in) · vs Placebo capsules	Steroid doses were reduced by 36% in the cineole group (mean 3.75 mg of prednisolone a day) and by 7% in the placebo group (mean 0.91 mg), p = 0.006. Twelve of 16 people on cineole and 4 of 16 on placebo managed a reduction (p = 0.012). More patients were able to cut their steroid tablets on cineole than on placebo Methods, limits and funding Outcomes: How far the daily dose of oral steroid tablets could be reduced (steroid-sparing effect) Limitations: Only 32 people. Steroid tapering was done by the trial team; people should never change steroid doses on their own. Funding and conflicts: Funding is not stated in the abstract; the full text was not read. Read: abstract
Juergens 2020 New Perspectives for Mucolytic, Anti-inflammatory and Adjunctive Therapy with 1,8-Cineole in COPD and Asthma: Review on the New Therapeutic Approach. Adv Ther · PMID 32200535 · DOI	Narrative review human and lab	Review of lab studies and trials of cineole in COPD and asthma	1,8-cineole (eucalyptol) Isolated compound 3 × 200 mg a day in the trials it summarises	The review states that earlier randomised trials of cineole (3 x 200 mg a day, 6 months) improved uncontrolled asthma and cut COPD flare-ups by 38.5% in winter. It also summarises lab work in human cells: NF-kappa-B control, lower cytokines, and an added effect with budesonide in vitro. Narrative review that supports the trial results; its 38.5% figure comes from the COPD trial Methods, limits and funding Outcomes: Summary of lab mechanisms and earlier trials Limitations: Narrative review, not systematic. Two authors (Worth, Juergens) ran the trials it describes. Conflict statement not read. Funding and conflicts: Not stated in the abstract. Read: abstract
Jun 2013 Effect of eucalyptus oil inhalation on pain and inflammatory responses after total knee replacement: a randomized clinical trial. Evid Based Complement Alternat Med · PMID 23853660 · DOI	Controlled trial	Adults after total knee replacement surgery (number of people not given in the abstract)	Eucalyptus oil, inhaled (a whole essential oil, not isolated cineole) Essential oil Inhaled for 30 minutes during passive knee movement 3 consecutive days · vs Almond oil inhaled the same way	Pain scores were lower with eucalyptus oil than with almond oil on all three days (p < .001). Systolic and diastolic blood pressure were lower on day 2. Heart rate, CRP and white blood cell count did not differ. A correction notice for this paper was published in 2026 (not read). Lower pain scores after knee surgery with eucalyptus oil smell than with almond oil smell Methods, limits and funding Outcomes: Pain on a 0 to 10 style visual scale, blood pressure, heart rate, CRP and white blood cell count Limitations: The two oils smell different, so people probably knew which they were getting, and pain is a rating people give themselves. The abstract gives no numbers. It is a whole oil, not cineole by itself. Funding and conflicts: Not stated in the abstract; the full text was not read. Read: abstract
Kehrl 2004 Therapy for acute nonpurulent rhinosinusitis with cineole: results of a double-blind, randomized, placebo-controlled trial. Laryngoscope · PMID 15064633 · DOI	Controlled trial	152 Adults with acute non-pus rhinosinusitis (sinus infection that is not yet pus-filled)	Cineole capsules (the product name is not given in the abstract) Isolated compound (1,8-cineole) in capsules Two 100 mg capsules three times a day, as given in the trial 7 days · vs Placebo capsules	The average symptom score started at 15.6 in both groups. In the cineole group it was 6.9 after 4 days and 3.0 after 7 days. In the placebo group it was 12.2 and 9.2. The authors call the difference clinically relevant and significant. Two people on cineole had mild side effects (heartburn and a rash). Faster fall in sinus symptom score than with placebo over 7 days Methods, limits and funding Outcomes: Sum score of symptoms and signs after 4 and 7 days Limitations: A short trial with an overall symptom score that mixes what people feel with what the doctor finds. The abstract reports no tests of blinding. Funding and conflicts: Funding is not stated in the abstract; the full text was not read. Read: abstract
Li 2022 Analysis of Anti-Cancer and Anti-Inflammatory Properties of 25 High-THC Cannabis Extracts. Molecules · PMID 36144796 · DOI	Laboratory research cells	Lab cell tests of 25 high-THC cannabis extracts	25 high-THC cannabis extracts, with terpene analysis (eucalyptol among 20 terpenes) Cannabis extracts · vs Untreated cells	Extracts slowed squamous cancer cell growth by 66% to 92%. Terpinene correlated with the anti-cancer effect (p = 0.002) and eucalyptol "came second, with pval of 0.094", which is not significant by the usual p < 0.05 rule. The authors say terpenes such as eucalyptol appear to modulate cannabinoid activity. A weak, non-significant link between eucalyptol and cancer cell killing by extracts, in dishes Methods, limits and funding Outcomes: Cancer-cell growth and inflammation genes, compared with terpene content Limitations: Cell dishes with extracts, not isolated eucalyptol. Correlation only. No cancer treatment effect in people. Funding and conflicts: The authors declare no conflict of interest; funders had no role. Read: abstract
Liapi 2007 Antinociceptive properties of 1,8-Cineole and beta-pinene, from the essential oil of Eucalyptus camaldulensis leaves, in rodents. Planta Med · PMID 17893834 · DOI	Animal research mouse and rat	Mice and rats	1,8-cineole and beta-pinene (from Eucalyptus camaldulensis leaves) Isolated compounds Not given in the abstract Acute tests · vs Morphine, naloxone	Cineole gave pain-test effects "comparable to morphine" in both tests, with a synergy with morphine, and naloxone did not block it. Beta-pinene acted differently. Pain-test effect in rodents Methods, limits and funding Outcomes: Tail-flick and hot-plate pain tests Limitations: Animal tests only. The authors still had mechanism work in progress. Funding and conflicts: Not stated in the abstract. Read: abstract
MacKenzie 2023 Determination of orally administered 1,8-Cineol in nasal polyp tissues from chronic rhinosinusitis patients using gas chromatography: mass spectrometry. Sci Rep · PMID 36869061 · DOI	Pharmacokinetic study	30 Adults with chronic rhinosinusitis with nasal polyps awaiting surgery	Orally given 1,8-cineole medicine Isolated compound Not given in the abstract 14 days before surgery	Cineole was detected in nasal polyp tissue after 14 days by mouth, with no clear link to body weight or BMI. The authors say this indicates it spreads through the body after swallowing. Shows that swallowed cineole reaches nasal tissue in people Methods, limits and funding Outcomes: Amount of cineole in nasal polyp tissue (GC-MS) Limitations: Detection only; it does not show benefit. Funded by the maker of the product. Funding and conflicts: Cassella-med (the maker) funded the study and supplied the medicine, and two authors work for it. The paper says the company had no influence on sampling, analysis or data. Read: abstract
Mathew 2017 Eucalyptus oil inhalation-induced seizure: A novel, underrecognized, preventable cause of acute symptomatic seizure. Epilepsia Open · PMID 29588965 · DOI	Case series	10 10 people with seizures after inhaling eucalyptus oil, three hospitals in India	Eucalyptus oil vapour Essential oil Not given in the abstract	Eight people had generalised tonic-clonic seizures and two had complex partial seizures. The authors say doctors rarely ask about eucalyptus oil in first-time seizures and want to raise awareness. Seizure after breathing eucalyptus oil vapour has been reported Methods, limits and funding Outcomes: Seizure type Limitations: Case report series; the abstract gives no amounts or ages. Funding and conflicts: Not stated in the abstract. Read: abstract
Mathew 2020 Essential oil-related status epilepticus: A small case series study. J Am Coll Emerg Physicians Open · PMID 33145540 · DOI	Case series	3 Three adults with status epilepticus linked to essential oils (India, 2018-2019)	Eucalyptus oil swallowed (two cases); balms with eucalyptus and camphor on the skin (one case) Essential oil and balms Not given in the abstract	Two adults had generalised status epilepticus after swallowing eucalyptus oil. The third had focal status epilepticus after rubbing on balms containing eucalyptus and camphor. The authors advise asking about essential oil exposure. Three adults with prolonged seizures linked to eucalyptus oil Methods, limits and funding Outcomes: Seizure type Limitations: Three cases. The balm contained camphor too, so eucalyptus cannot be blamed alone. Funding and conflicts: Not stated in the abstract. Read: abstract
Michalsen 2024 The impact of cineole treatment timing on common cold duration and symptoms: Non-randomized exploratory clinical trial. PLoS One · PMID 38236839 · DOI	Clinical trial	329 Adults who developed a common cold (out of 522 enrolled before they were ill)	Soledum (CNL-1976), a branded cineole capsule Isolated compound (1,8-cineole) in capsules 200 mg three times a day, as given in the trial Up to about 15 days	People who started within 12 hours had the lowest burden of illness, 38% lower overall (p < 0.0001), and a shorter time to remission (8.9 days against 10.7 days for the latest starters, p < 0.05). Side effects judged possibly related to the capsule were reported by 4.3% of people. Starting the capsule earlier in a cold went with a lighter and shorter cold Methods, limits and funding Outcomes: Burden of illness over time (WURSS-11 symptom survey) Limitations: No placebo group and no randomisation, so earlier starters may differ from later starters, and colds get better by themselves. It cannot show the capsule works. Industry-funded. Funding and conflicts: All authors received financial support from Cassella-med or MCM Klosterfrau (the makers). Some authors report fees from other drug companies. Registration: EudraCT 2020-000860-51 Read: abstract
Miyazawa 2001 Oxidation of 1,8-cineole, the monoterpene cyclic ether originated from eucalyptus polybractea, by cytochrome P450 3A enzymes in rat and human liver microsomes. Drug Metab Dispos · PMID 11159812	Laboratory research human and rat liver tissue	Human and rat liver microsomes; enzymes made in insect cells	1,8-cineole Isolated compound · vs Enzyme inhibitors	Human liver microsomes turned 1,8-cineole into 2-exo-hydroxy-1,8-cineole, mainly by CYP3A4 (and about one quarter as fast by CYP3A5). The ketoconazole block and the link with CYP3A4 amounts in 18 human livers support this. The authors call it a very good CYP3A4 substrate. Cineole is broken down in the liver mainly by CYP3A4 Methods, limits and funding Outcomes: How the liver enzymes change cineole Limitations: Lab enzymes. It does not show that cineole changes the levels of other drugs. Funding and conflicts: Not stated in the abstract. Read: abstract
National Library of Medicine 2026 PubChem GHS classification for 1,8-Cineole (CID 2758) PubChem PUG-View, retrieved 2026-10-25 · Source	Authoritative guidance n/a	n/a	n/a	Aggregated from 2,296 reports by companies in 17 notifications: H226 flammable liquid and vapour (98.7%) and H317 may cause an allergic skin reaction (84.2%). 8 of 2,296 reports said it does not meet GHS hazard criteria. Aggregated from 2,296 reports by companies in 17 notifications: H226 flammable liquid and vapour (98.7%) and H317 may cause an allergic skin reaction (84.2%). 8 of 2,296 reports said it does not meet GHS hazard criteria. Methods, limits and funding Outcomes: Hazard classes companies report for the pure chemical Limitations: These are classes for the pure chemical, as notified by companies, not measured rates in users. Funding and conflicts: n/a Read: full-text
National Library of Medicine 2026 PubChem compound summary: 1,8-Cineole (CID 2758) PubChem REST API, retrieved 2026-10-25 · Source	Database n/a	n/a	n/a	CID 2758. Title 1,8-Cineole; IUPAC name 1,3,3-trimethyl-2-oxabicyclo[2.2.2]octane; formula C10H18O; molecular weight 154.25; InChIKey WEEGYLXZBRQIMU-UHFFFAOYSA-N. Synonyms include eucalyptol, cineole, 1,8-cineol, cajeputol, 1,8-epoxy-p-menthane and CAS number 470-82-6. CID 2758. Title 1,8-Cineole; IUPAC name 1,3,3-trimethyl-2-oxabicyclo[2.2.2]octane; formula C10H18O; molecular weight 154.25; InChIKey WEEGYLXZBRQIMU-UHFFFAOYSA-N. Synonyms include eucalyptol, cineole, 1,8-cineol, cajeputol, 1,8-epoxy-p-menthane and CAS number 470-82-6. Methods, limits and funding Outcomes: Chemical identity of eucalyptol / 1,8-cineole Limitations: A database record, not a study. Funding and conflicts: n/a Read: full-text
Navrátilová 2024 1,8-cineole (eucalyptol) in a therapy of respiratory diseases. Ceska Slov Farm · PMID 39937641 · DOI	Narrative review human and lab	Review of cineole in respiratory disease	1,8-cineole (eucalyptol) Isolated compound	Says cineole comes mainly from eucalyptus oil, is present in plants of the mint (Lamiaceae), myrtle (Myrtaceae) and ginger (Zingiberaceae) families, is used in food, cosmetics and perfumery, and has been confirmed in lab, animal and clinical studies; medicinal products and food supplements containing it are sold. Short review; no new data Methods, limits and funding Outcomes: Summary Limitations: Short abstract; the full paper was not read. Funding and conflicts: Not stated in the abstract. Read: abstract
Panda 2021 Clinico-laboratory characteristics and outcome of patients with eucalyptus oil-induced/provoked seizures: A case series and systematic review of the published patients. Trop Doct · PMID 34282989 · DOI	Systematic review	110 110 reported cases (49 children) of seizures linked to eucalyptus oil, plus five new children	Eucalyptus oil by skin, inhalation or swallowing Essential oil	Inhalation was the most common route among the 110 cases. The most common seizure type was generalised tonic-clonic. Most had an uneventful recovery, and adults were less likely to have prolonged or repeated seizures or need intensive care or ventilation. Seizures after eucalyptus oil have been reported from skin, vapour and swallowing Methods, limits and funding Outcomes: Type, treatment and outcome of seizures Limitations: A pooled case report review, which cannot show how common seizures are. Funding and conflicts: Not stated in the abstract. Read: abstract
Pires 2024 Characterisation of Cannabis-Based Products Marketed for Medical and Non-Medical Use Purchased in Portugal. Molecules · PMID 38930803 · DOI	Lab analysis product	Cannabis-based products bought in Portugal (drinks, herbs, oils, cosmetics)	Cannabis products Products · vs Label values	Beverages had no detectable cannabinoids despite suggestive packaging, and oils often differed from the declared contents, some with much more CBD than labelled. Cannabinoid labels did not match contents in many products Methods, limits and funding Outcomes: Measured cannabinoids against the label Limitations: Cannabinoids only, not terpenes. Funding and conflicts: The authors declare no conflicts of interest. Read: abstract
Raal 2007 Composition of the essential oil of Salvia officinalis L. from various European countries. Nat Prod Res · PMID 17487611 · DOI	Chemical analysis plant oil	Sage (Salvia officinalis) oils from Estonia and other European countries	Sage essential oil Leaves	The main components were 1,8-cineole, camphor, alpha-thujone, beta-thujone, borneol and viridiflorol (40 compounds). The authors note the comparatively high concentration of toxic thujones in Estonian sage. The abstract gives no cineole percentages. Cineole is one of the main compounds in sage oil, alongside camphor and thujones Methods, limits and funding Outcomes: Composition by capillary gas chromatography Limitations: No percentages in the abstract. The thujones are a separate safety concern with sage oil. Funding and conflicts: Not stated in the abstract. Read: abstract
Sai Chandar 2021 Eucalyptus Oil-Induced Seizures in Children: A Single-Center Prospective Study. Cureus · PMID 33927923 · DOI	Case series	17 Children with a first seizure or breakthrough seizure after eucalyptus oil, one hospital in South India (2 years)	Eucalyptus oil drops swallowed in water or milk Essential oil Different amounts Follow-up 6 to 9 months	All 17 children had a generalised tonic-clonic seizure about 20 minutes (median; range 10 to 120) after swallowing the oil. Median age was 3.75 years. Scans were normal in all; none had another seizure in 6 to 9 months of follow-up. The authors call it an under-recognised cause of seizures in children. Swallowed eucalyptus oil caused seizures in 17 children, all recovered Methods, limits and funding Outcomes: Seizure type, timing, scans, EEG and recurrence Limitations: Small, single-centre series. Unknown how many children swallow the oil without seizures. Funding and conflicts: No competing interests declared. Read: abstract
Santos 2000 Antiinflammatory and antinociceptive effects of 1,8-cineole a terpenoid oxide present in many plant essential oils. Phytother Res · PMID 10861965 · DOI	Animal research rat and mouse	Rats and mice	1,8-cineole Isolated compound 100 to 400 mg/kg by mouth in the effective range Acute tests · vs Vehicle; naloxone in one test	Cineole reduced inflammation in rat paw and granuloma tests and pain behaviour in mouse formalin and acetic acid tests. Naloxone did not reverse the pain effect, so it does not seem to work through opioid receptors. It also reduced movement and lengthened pentobarbital sleeping time in mice, which the authors read as a possible depressant effect on the nervous system. Less inflammation and pain behaviour in rodents; also a sedating effect in mice Methods, limits and funding Outcomes: Paw swelling, pain behaviour, movement, sleeping time Limitations: Animal work at doses far above any use by people. Funding and conflicts: Not stated in the abstract. Read: abstract
Schwabe 2023 Uncomfortably high: Testing reveals inflated THC potency on retail Cannabis labels. PLoS One · PMID 37043421 · DOI	Lab analysis product	23 retail Colorado cannabis flower samples from 10 dispensaries	Cannabis flower Flower · vs Label values	Average measured THC was 14.98%, which was 23.1% lower than the lowest label value and 35.6% lower than the highest. About 70% of samples were more than 15% lower than labelled. Cannabis labels for THC overstated what was in the package Methods, limits and funding Outcomes: Measured THC against the label Limitations: Looks only at THC, not at terpenes. Small sample in one US region. Funding and conflicts: Not stated in the abstract. Read: abstract
Sima 2025 A Multicenter, Randomized, Controlled Clinical Trial on the Efficacy and Safety of Eucalyptol, Limonene, and Pinene Enteric Capsules in the Treatment of Chronic Rhinosinusitis With Nasal Polyps Postoperatively. Clin Transl Allergy · PMID 41327929 · DOI	Controlled trial	174 Adults with chronic rhinosinusitis with nasal polyps, after sinus surgery (multi-centre, China)	Eucalyptol + limonene + pinene enteric capsules (ELP), a three-terpene mixture, together with a steroid nose spray Mixture of three isolated terpenes in enteric capsules Not given in the abstract 12 weeks · vs Steroid nose spray alone (assigned 1:2, so more people got the capsules)	The capsule-plus-spray group had greater improvement on CT scan (Lund-Mackay) and endoscopy (Lund-Kennedy) scores (p = 0.029 and 0.025), shorter nose-clearance time at week 4 (p = 0.015) and lower levels of several inflammation markers in a subgroup. Side effects did not differ between groups. Registered as ChiCTR2200055224. Slightly better scan and endoscopy scores when a three-terpene capsule was added to the nose spray Methods, limits and funding Outcomes: Scan and endoscopy scores, nose-clearance test, symptom questionnaire (SNOT-22), inflammation markers in nasal fluid, side effects Limitations: This tests a mixture of three terpenes, so the effect cannot be given to eucalyptol alone. The abstract does not say whether anyone was blinded. Many outcomes were tested, and only some improved. Funding and conflicts: The authors declare no conflicts of interest. Registration: ChiCTR2200055224 Read: abstract
Suresh 2025 Fatal Eucalyptus Oil Poisoning in an Adult Male: A Case Report With Comprehensive Autopsy and Histopathological Findings. Cureus · PMID 40432665 · DOI	Case report	1 An adult man who swallowed 15 mL of eucalyptus oil stored in a cough-syrup bottle (India)	Eucalyptus oil swallowed by mistake Essential oil 15 mL Died in hospital	Seizures began within minutes, then unresponsiveness and weak breathing; he had a cardiac arrest, was revived, kept seizing, and died at a second hospital. The post-mortem showed damage to the tongue, windpipe, stomach and gut, lung emphysema, fatty liver change and kidney damage. The authors stress public awareness of potential lethality. A fatal outcome after swallowing 15 mL of pure oil Methods, limits and funding Outcomes: Clinical course and post-mortem findings Limitations: One case. Funding and conflicts: No funding or competing interests declared. Read: abstract
Takaishi 2012 1,8-cineole, a TRPM8 agonist, is a novel natural antagonist of human TRPA1. Mol Pain · PMID 23192000 · DOI	In vitro and animal cells and animal	Human TRP channels in cells; a sensory irritation test in animals	1,8-cineole Isolated compound Not given in the abstract · vs Other compounds, including 1,4-cineole	1,8-cineole switched on TRPM8 (the cool sensor) and blocked human TRPA1 (a pain and irritation sensor), and in animals it reduced sensory irritation caused by two TRPA1 triggers. 1,4-cineole, a close relative, activated both channels. The authors suggest it is a natural TRPA1 antagonist with possible analgesic effects. A lab and animal explanation for the cooling feeling and for reduced irritation Methods, limits and funding Outcomes: Activity on cold-sensing (TRPM8) and pain-sensing (TRPA1) channels Limitations: Cells and animals only. No pain study in people tests this. Funding and conflicts: Not stated in the abstract. Read: abstract
The Royal Children's Hospital Melbourne 2021 Eucalyptus Oil Poisoning (Clinical Practice Guideline, PIC endorsed) RCH Clinical Practice Guidelines (last updated July 2021; read 2026-10-25) · Source	Authoritative guidance n/a	n/a	n/a	Small swallowed amounts of pure oil (5 mL or more) can lead to severe symptoms. 2 to 3 mL can cause mild central nervous system depression (drowsiness, dizziness, unsteadiness) and 5 mL or more significant depression with coma. Symptoms usually start within 30 minutes but may be delayed up to 4 hours, and usually settle within 24 hours. Main things to watch are CNS depression and breathing problems. The guideline lists the Australian Poisons Information Centre number 13 11 26 for 24-hour advice. Small swallowed amounts of pure oil (5 mL or more) can lead to severe symptoms. 2 to 3 mL can cause mild central nervous system depression (drowsiness, dizziness, unsteadiness) and 5 mL or more significant depression with coma. Symptoms usually start within 30 minutes but may be delayed up to 4 hours, and usually settle within 24 hours. Main things to watch are CNS depression and breathing problems. The guideline lists the Australian Poisons Information Centre number 13 11 26 for 24-hour advice. Methods, limits and funding Outcomes: What a children's hospital guideline says about eucalyptus oil poisoning Limitations: An Australian hospital guideline for clinicians; it states no author. It was read through a page-reading tool, not as a PDF. Funding and conflicts: n/a Read: summary-only
Tibballs 1995 Clinical effects and management of eucalyptus oil ingestion in infants and young children. Med J Aust · PMID 7651249 · DOI	Case series	109 Children under 9 admitted to the Royal Children's Hospital, Melbourne, 1981 to 1992	Eucalyptus oil swallowed by accident Essential oil Known volumes in 27 children (group averages 1.7 to 7.5 mL) Hospital stay mean 22 hours	Of 109 children (mean age 23.5 months), 59% had effects. 31 (28%) had depressed consciousness: 27 drowsy, 3 unconscious after 5 to 10 mL, and 1 unconscious with weak breathing after an estimated 75 mL. 37% vomited, 15% were unsteady, and 11% had lung disease. All recovered. Among 27 children with known doses, effects scaled with the volume (nil after a mean of 1.7 mL; major poisoning after 7.5 mL). The author concludes that significant drowsiness should be expected after 5 mL or more of 100% oil and minor drowsiness may follow 2 to 3 mL. Swallowing a teaspoon or so of pure oil can make a toddler seriously unwell Methods, limits and funding Outcomes: Symptoms and signs, the amount swallowed, and hospital stay Limitations: Retrospective hospital review, so children seen were the ones sick enough to come in. Doses were often estimated. The oil is not pure cineole. Funding and conflicts: Not stated in the abstract. Read: abstract
US Food and Drug Administration 2026 US Code of Federal Regulations Title 21, section 172.515: Synthetic flavoring substances and adjuvants eCFR (API; text version dated 2026-10-01, retrieved 2026-10-25) · Source	Authoritative guidance n/a	n/a	n/a	Section 172.515 says synthetic flavouring substances and adjuvants may be safely used in food under the stated conditions. The list includes "Eucalyptol; 1,8-epoxy-p-menthane; cineole" (and also 1,4-cineole). Section 172.515 says synthetic flavouring substances and adjuvants may be safely used in food under the stated conditions. The list includes "Eucalyptol; 1,8-epoxy-p-menthane; cineole" (and also 1,4-cineole). Methods, limits and funding Outcomes: Whether eucalyptol is on the FDA list of synthetic food flavourings Limitations: A food-flavouring rule. It says nothing about inhaling, vaping or taking cineole as a medicine, supplements, or use in cannabis products. Funding and conflicts: n/a Read: full-text
Worth 2009 Concomitant therapy with Cineole (Eucalyptole) reduces exacerbations in COPD: a placebo-controlled double-blind trial. Respir Res · PMID 19624838 · DOI	Controlled trial	242 Adults with stable COPD (multi-centre, winter-time)	Cineole capsules (the product name is not given in the abstract) Isolated compound (1,8-cineole) in capsules 200 mg three times a day, as given in the trial 6 months · vs Placebo capsules, with usual COPD medicines in both groups	Flare-ups were significantly lower with cineole than with placebo for frequency, severity and duration combined. Lung function, breathlessness and quality of life, taken together, were also significantly better than with placebo. The abstract says side effects were comparable in both groups. Registered as ISRCTN07600011. Fewer COPD flare-ups over 6 months, as an add-on to usual treatment Methods, limits and funding Outcomes: Number, severity and length of flare-ups (exacerbations) combined; lung function, breathlessness and quality of life Limitations: One trial from one research group; the abstract gives no numbers for individual outcomes. It tests one cineole product, so it says nothing about eucalyptus oil, vapour or cannabis. Funding and conflicts: Funded by a grant from Cassella-med, Cologne, Germany, the maker of cineole products (read in the full text on Europe PMC). The authors declare no competing interests. Registration: ISRCTN07600011 Read: abstract and full text (funding statement)
Worth 2012 Patients with asthma benefit from concomitant therapy with cineole: a placebo-controlled, double-blind trial. J Asthma · PMID 22978309 · DOI	Controlled trial	247 Adults with confirmed asthma (multi-centre)	Cineole capsules (the product name is not given in the abstract) Isolated compound (1,8-cineole) in capsules 200 mg three times a day, as given in the trial 6 months · vs Placebo capsules, with usual asthma treatment	The cineole group improved more on the combined measure than the placebo group (p = 0.0027). Single measures were also significant: FEV1 (p = 0.0398), asthma symptoms (p = 0.0325) and asthma quality of life (p = 0.0475). The abstract gives no effect sizes. Better lung function, symptoms and quality of life in asthma, as an add-on to usual treatment Methods, limits and funding Outcomes: Lung function, asthma symptoms and asthma quality of life (combined primary measure) Limitations: The single-measure p-values are close to 0.05. The abstract gives no sizes of change. The same research group, and a similar design, as the COPD trial. Funding and conflicts: Funding is not stated in the abstract; the full text was not read. Read: abstract
Zhao 2026 Efficacy and safety of mucolytic agents in patients with chronic obstructive pulmonary disease: a systematic review and network meta-analysis. BMC Pulm Med · PMID 41688985 · DOI	Network meta analysis	4408 Adults with COPD; 18 randomised trials of mucolytic drugs	Several mucolytic drugs including cineole Various · vs Placebo, usual care or another drug	For reducing flare-ups and for the lowest rate of side effects, cineole ranked highest (SUCRA 87.72% and 79.04%). Other drugs ranked first for lung function (erdosteine) and inflammation markers (tyloxapol). The authors call for larger multi-centre trials with long-term safety data. Cineole ranked first for fewer flare-ups and fewer side effects among COPD mucolytics, in an indirect ranking Methods, limits and funding Outcomes: Inflammation markers, lung function, ROS, flare-up rates and side effects Limitations: Rankings are not proof of a difference; the abstract does not say how many cineole trials were included. Probably few, and mostly the trials above. Funding and conflicts: The authors declare no competing interests. Read: abstract
Zheljazkov 2020 Grinding and Fractionation during Distillation Alter Hemp Essential Oil Profile and Its Antimicrobial Activity. Molecules · PMID 32872359 · DOI	Chemical analysis plant	Hemp (Cannabis sativa) biomass distilled into essential oil	Hemp steam-distilled essential oil fractions Hemp plant material Different distillation times (0 to 180 min) · vs Ground against unground material	Eucalyptol is named as a compound whose concentration could be raised: "high eucalyptol EO" came from the first 5 minutes of distilling ground material, or the 80 to 120 minute fraction of unground material. The abstract gives no percentages for eucalyptol. Shows that hemp essential oil contains eucalyptol Methods, limits and funding Outcomes: Composition of hemp essential oil over time Limitations: Industrial hemp, not high-THC flower. No amounts in the abstract. Funding and conflicts: The authors declare no conflict of interest. Read: abstract
Zheljazkov 2022 Terpenes and Cannabinoids Yields and Profile from Direct-Seeded and Transplanted CBD-Cannabis sativa. J Agric Food Chem · PMID 35436102 · DOI	Chemical analysis plant	One high-CBD hemp variety (Culver) grown in Oregon in two planting systems	Hemp essential oil Hemp flower tops (colas), leaves, chaff, male flowers One harvest · vs Two planting systems compared	The abstract lists 1,8-cineole among the compounds that were lower in oil from the transplanted-clone system than from the densely seeded system. No eucalyptol percentage is given in the abstract. Shows that 1,8-cineole is in hemp oil, and varies with how it is grown Methods, limits and funding Outcomes: Terpene and cannabinoid composition of the oil Limitations: One hemp variety and a steam-distilled oil. Does not describe smoked or vaped THC flower. Funding and conflicts: Not stated in the abstract. Read: abstract
Čmiková 2023 Chemical Composition and Biological Activities of Eucalyptus globulus Essential Oil. Plants (Basel) · PMID 36903935 · DOI	Chemical analysis plant oil	One commercial Eucalyptus globulus essential oil	Eucalyptus globulus essential oil Leaf oil	1,8-cineole was 63.1% of the oil, with p-cymene 7.7%, alpha-pinene 7.3% and limonene 6.9%; monoterpenes made up 99.2% of the oil. Cineole was the main compound, 63.1%, in this one oil Methods, limits and funding Outcomes: Composition by GC and GC/MS Limitations: One oil sample. Other oils differ by species, place and batch. Funding and conflicts: The authors declare no conflict of interest. Read: abstract

What we do not know yet

What the evidence supports: low certainty at best for cineole capsules in airway disease, mostly funded by the maker; very low or insufficient for everything else.
No independent repeat of the COPD, asthma and bronchitis trials was found, and no trial in children.
No trial of eucalyptol inhaled, smoked or vaped, or as part of cannabis.
The three-terpene capsule trials cannot show what eucalyptol alone does.
Poisoning data are about the whole oil; the share due to cineole is unknown. Pregnancy, breastfeeding and drug interaction data are missing.
Our cannabis lab data hold no eucalyptol measurements, and no source on terpene label accuracy was found.
Regulator listings for cineole capsule products, LiverTox and LactMed were not read.

How new research is added

New studies are found by a saved PubMed search and are placed in a review queue. A person reads each one before it changes any evidence rating or safety wording. New publications can change what this page says.

Lab markers

What changed in blood or saliva tests during trials. A changed number is not the same as feeling or being healthier, and we give no "normal ranges".

Other 8

▼

COPD flare-ups (exacerbations)

Lowered in trials

Sudden worsening of breathing symptoms in COPD, often needing extra treatment.

Low certainty

Results and what it means

Why it was measured

Flare-ups are what cause hospital stays and lung damage in COPD.

Statistical vs. clinical meaning

A clinical outcome, from one trial funded by the maker.

Safety implication

Adverse events comparable to placebo in the abstract.

Study	Result	People	Product
⁴¹	Frequency, severity and duration of flare-ups together were significantly lower than with placebo over 6 months; adverse events were comparable.	242 adults with stable COPD	Cineole capsules, 200 mg three times a day, plus usual treatment

^{41 43}

●

Lung function (FEV1)

Improved in trials

How much air a person can blow out in the first second.

Low certainty

Results and what it means

Why it was measured

It measures how open the airways are.

Statistical vs. clinical meaning

Statistically significant but p-values are near 0.05 and sizes are not in the abstracts.

Safety implication

None reported in the abstracts.

Study	Result	People	Product
⁴²	FEV1 improved significantly more than on placebo (p = 0.0398); the size of change is not in the abstract.	247 adults with asthma	Cineole capsules for 6 months
⁴¹	Lung function, breathlessness and quality of life improved together as multiple criteria (significant against placebo).	242 adults with COPD	Cineole capsules for 6 months

^{42 41}

▼

Cough fits

Lowered in trials

How often a person has a bout of coughing.

Low certainty

Results and what it means

Why it was measured

Cough is the main complaint in acute bronchitis.

Statistical vs. clinical meaning

A symptom score that people report.

Safety implication

No safety problem named in the abstract.

Study	Result	People	Product
⁵	Cough fits were fewer after 4 days (p = 0.0001) and the Bronchitis Sum Score improved (p = 0.0383).	242 adults with acute bronchitis	Cineole capsules for 10 days

⁵

▼

Sinus symptom sum score

Lowered in trials

A total of ratings for sinus symptoms (pain, blockage, discharge) and signs found by the doctor.

Moderate certainty

Results and what it means

Why it was measured

It is the usual way to judge sinus treatment.

Statistical vs. clinical meaning

A network meta-analysis rated the evidence for acute post-viral sinusitis as moderate certainty.

Safety implication

Heartburn and a rash in two people on cineole.

Study	Result	People	Product
¹⁸	Score fell from 15.6 to 3.0 with cineole and to 9.2 with placebo after 7 days.	152 adults with acute non-pus rhinosinusitis	Cineole capsules for 7 days

^{18 9}

▼

Daily dose of oral steroid tablets

Lowered in trials

How much prednisolone a person needs a day to keep their asthma controlled.

Very low certainty

Results and what it means

Why it was measured

A lower steroid dose means fewer steroid side effects.

Statistical vs. clinical meaning

Only 32 people.

Safety implication

Steroid doses should only be changed by a doctor.

Study	Result	People	Product
¹⁵	Steroid dose fell by 36% on cineole against 7% on placebo (p = 0.006).	32 adults with steroid-dependent severe asthma	Cineole capsules for 12 weeks

¹⁵

▼

Pain score (visual analogue scale)

Lowered in trials

A rating of pain on a line from no pain to worst pain.

Very low certainty

Results and what it means

Why it was measured

It is how most pain trials measure pain.

Statistical vs. clinical meaning

Self-rated, probably not blinded; no numbers in the abstract.

Safety implication

None reported in the abstract.

Study	Result	People	Product
¹⁷	Pain scores were lower with eucalyptus oil inhalation than almond oil on all 3 days (p < .001); heart rate, CRP and white blood cell count did not differ.	Adults after knee replacement	Eucalyptus oil inhaled 30 minutes a day

¹⁷

▼

NF-kappa-B activity in human cells

Lowered in trials

NF-kappa-B is a protein that switches on many inflammation genes.

Very low certainty

Results and what it means

Why it was measured

Lowering it could explain a calming effect on inflammation.

Statistical vs. clinical meaning

Lab only.

Safety implication

None.

Study	Result	People	Product
⁷	Reduced NF-kappa-B activity and movement of p65 into the nucleus in LPS-stimulated human cell lines, and nuclear p65 in human blood cells.	Human U373 and HeLa cells and blood cells	1,8-cineol

⁷

▼

Pain behaviour and paw swelling in rodents

Lowered in trials

How much an animal licks, writhes or withdraws, and how swollen a paw becomes.

Very low certainty

Results and what it means

Why it was measured

Standard first tests for pain and swelling compounds.

Statistical vs. clinical meaning

Animal only.

Safety implication

Reduced movement and longer sleeping time suggest a sedating effect at these doses.

Study	Result	People	Product
³³	Less swelling and less chemical pain behaviour; also less movement and longer sleeping time.	Rats and mice	1,8-cineole by mouth, 100 to 400 mg/kg
²⁰	Pain-test effects compared to morphine in tail-flick and hot-plate tests.	Mice and rats	1,8-cineole

^{33 20}

Safety

What studies and official sources say about side effects, medicines and who should check first. Each point shows what kind of evidence it comes from.

Main points to know 5

Swallowing eucalyptus oil can poison small children. Eucalyptus oil is mostly cineole. In a Melbourne hospital review of 109 young children, 59% had effects, 28% were drowsy or unconscious, and one child fell unconscious with weak breathing after swallowing an estimated 75 mL; all recovered. A hospital guideline says 2 to 3 mL can cause drowsiness and unsteadiness and 5 mL or more can cause coma, with symptoms starting within 30 minutes but sometimes up to 4 hours later. A state health department says as little as 2 mL can cause significant poisoning in an infant. These are figures for the whole oil, not for cineole capsules. Case series ^{39 38 6}
Seizures have been reported after eucalyptus oil by mouth, skin or vapour. A report of 17 children found generalised seizures about 20 minutes (median) after swallowing the oil, all with normal scans and no repeat seizures in 6 to 9 months. A pooled review of 110 cases (49 children) found inhalation was the most common route, and most people recovered. Adults have also had seizures, severe acidosis, and in one case a fatal outcome after swallowing 15 mL. A series of 10 people had seizures after breathing eucalyptus oil vapour. These reports cannot show how often seizures happen. Case series ^{32 29 22 13 36 23}
Official limits for young children and for people with seizures. The European herbal committee (EMA/HMPC, 2024) says eucalyptus oil medicines must not be used in children under 24 months, because cineole preparations like other essential oils can cause laryngospasm (a tight spasm of the voice box), nor in children with a history of seizures, nor in people with allergy to eucalyptus oil or cineole. Inhalation under 3 years and oral use under 12 years are listed as not established for lack of data. Pregnancy and breastfeeding: not recommended for lack of data. Authoritative guidance ⁴
Skin allergy and irritation. Of 2,296 company reports, 84.2% classify pure 1,8-cineole as able to cause an allergic skin reaction and 98.7% as a flammable liquid. The EU herbal committee lists allergic reactions (including severe) for all routes and contact eczema for skin use. These are classifications and committee lists, not measured rates in users. Authoritative guidance ^{26 4}
In the capsule trials, side effects were mostly mild. In the COPD trial adverse events were comparable between cineole and placebo. In the sinusitis trial 2 of 76 people on cineole had heartburn or a rash. In the open-label cold trial 4.3% reported side effects judged possibly related. These were short trials mostly funded by or linked to the maker, and none was designed to detect rare harms. Controlled trial ^{41 18 24}

Side effects 6

Effect	How often	Severity and recovery	Evidence
Drowsiness, vomiting, unsteadiness, seizures, coma and weak breathing after swallowing eucalyptus oil Whole oil swallowed by accident, not cineole capsules.	59% of 109 hospitalised young children had effects; 28% had depressed consciousness	moderate to life-threatening All 109 children recovered; one adult died after 15 mL	Case series ^{39 36}
Seizures from eucalyptus oil (swallowed, on the skin or breathed in) A case collection cannot show how often it happens.	Not known; 110 published cases were pooled and 17 children were seen at one hospital in 2 years	severe Most recovered without repeat seizures	Systematic review ^{29 32 22}
Laryngospasm (spasm of the voice box) in small children The stated reason for the EU rule against use under 24 months. The monograph gives no case numbers.	Not known	severe Not described	Authoritative guidance ⁴
Allergic reaction or contact eczema A classification of the pure chemical.	Frequency not known (EU herbal committee). 84.2% of 2,296 company reports classify pure cineole as a skin sensitiser	mild to severe (severe allergic reactions are listed) Not described	Authoritative guidance ^{4 26}
Heartburn, stomach upset (capsules or oral oil) The EU herbal committee lists stomach reactions for oral use and says use with caution in inflamed or ulcerated gut.	2 of 76 people on cineole capsules (heartburn and a rash) in one 7-day trial	mild Not described	Controlled trial ^{18 4}
Sedation in mice Less movement and longer pentobarbital sleep. No human sedation study was found.	Seen at 100 to 400 mg/kg in mice	unknown in people Not described	Animal research ³³

Liver

No human case of liver injury from cineole was found in the sources read, and LiverTox was not read. A post-mortem after a fatal 15 mL swallow of eucalyptus oil showed fatty change in the liver among widespread organ damage, which does not show the cause. Human liver enzymes break cineole down, mainly CYP3A4. ^{36 25}

How often. No human rate was found.

Monitoring. No agency monitoring advice was read.

This is a safety connection. It is not evidence that Eucalyptol (1,8-Cineole) supports liver health.

Medicines and supplements 5

With	Why it matters	Importance	Evidence	What to do
Drugs broken down by CYP3A4 (many medicines) prescription	In human liver tissue and recombinant enzymes cineole is a very good CYP3A4 substrate, broken down to 2-exo-hydroxy-1,8-cineole. The abstract does not say it changes the blood levels of other medicines.	Unknown. No study measured whether cineole changes levels of another drug.	Laboratory research Not enough evidence ^{25 4}	Tell a doctor or pharmacist about any cineole or eucalyptus product if you take regular medicines. The EU herbal committee lists no interactions as reported.
Oral steroid tablets (asthma) prescription	In the 2003 trial the cineole group managed to cut steroid tablets further than the placebo group.	This is an intended trial effect, not an interaction. Nobody should lower steroid tablets without a doctor.	Controlled trial Very low certainty ¹⁵	Do not change steroid tablets because of a cineole product.
Sedatives, sleeping medicines and alcohol sedatives	In mice cineole lowered movement and lengthened pentobarbital sleeping time.	Unknown in people.	Animal research Not enough evidence ³³	Take care with anything that makes you sleepy. This is a signal from mice.
Opioids (morphine) prescription	In rodent pain tests cineole worked together with morphine ("synergism").	Unknown in people.	Animal research Not enough evidence ²⁰	Ask a doctor if you take opioid pain medicines.
THC (cannabis) cannabis	No study measured whether eucalyptol changes THC effects. The cannabis studies read are associations and cell dishes.	Unknown.	Observational Not enough evidence ^{8 19}	Do not assume a terpene makes THC safer or milder. THC impairment, anxiety and dependence risks do not go away. Sources on THC were not read for this page.

Who should check first 8

Situation	Advice	Evidence
Children under 24 months, or any child with a history of seizures	The EU herbal committee says eucalyptus oil medicines must not be used. Keep all eucalyptus products out of reach of small children, and do not use them in vaporisers at floor level.	Authoritative guidance ^{4 3}
Allergy to eucalyptus oil or cineole	Do not use. Severe allergic reactions are listed.	Authoritative guidance ⁴
Pregnancy and breastfeeding	The EU herbal committee says not recommended because safety has not been established. LactMed was not read.	Authoritative guidance ⁴
Broken or irritated skin; full hot baths in some conditions	The EU herbal committee says not to apply oil on broken or irritated skin, and lists cases (large skin injuries, high fever, severe infection, severe circulatory problems, cardiac failure) where full hot baths are contraindicated.	Authoritative guidance ⁴
Inflamed or ulcerated stomach or gut (oral use)	The EU herbal committee says use with caution.	Authoritative guidance ⁴
Asthma, COPD or a chest infection	The EU herbal committee says to see a doctor if breathlessness, fever or pus appears or symptoms worsen. Do not replace prescribed inhalers or tablets.	Authoritative guidance ⁴
Mental health, driving and impairment	No study of cineole and mental health or driving was found; the EU herbal committee says no studies on driving have been performed, and mice became sleepy on large doses. If eucalyptol comes with THC in cannabis, the THC risks apply (impairment, anxiety, dependence); THC sources were not read for this page.	Authoritative guidance ^{4 33}
Teens and older adults	Teens: the EU age limits above apply. No trial or source read looked at older adults separately.	Authoritative guidance ⁴

Overdose, product quality and regulators

Summary. Pure eucalyptus oil is the main danger, especially swallowed by small children: drowsiness, unsteadiness, breathing trouble, seizures and coma. The oil is mostly cineole, but the reports do not isolate cineole, and capsule trials in adults did not show worse side effects than placebo.

Animal. In mice, 100 to 400 mg/kg by mouth lowered movement and lengthened sleeping time. The EU herbal committee says adequate tests of reproductive toxicity, genotoxicity and carcinogenicity have not been performed.

Human doses studied. The respiratory trials used 3 x 200 mg a day of cineole capsules for 7 days to 6 months in adults, as given in the trials. These figures describe what the studies tested, not what to take.

High dose or long term signals. Only the 6-month trials give long exposure, and they are funded by or linked to the maker. No long-term data beyond that.

Overdose response. A hospital guideline says 2 to 3 mL of pure oil can cause mild central nervous system depression and 5 mL or more coma in children, with symptoms starting within 30 minutes and up to 4 hours later, usually settling in 24 hours. The EU herbal committee lists stomach symptoms, breathing problems, CNS depression, loss of consciousness, convulsions and ataxia as overdose effects. A hospital guideline names the Poisons Information Centre in Australia (13 11 26).

Genotoxicity. Not read. The EU herbal committee says adequate genotoxicity tests have not been performed on the oil.

No study of how well cannabis or vape labels state eucalyptol was found. Studies of cannabis products show label claims for THC and cannabinoids often do not match what is in the package, so terpene numbers on labels should be treated with caution too.

THC on flower labels. In 23 retail flower samples from 10 Colorado dispensaries, measured THC averaged 14.98%, 23.1% below the lowest label value and 35.6% below the highest. ³⁴

Cannabinoid products in Portugal. Drinks had no detectable cannabinoids despite suggestive packaging, and oils often differed from the label, some with much more CBD than labelled. ³⁰

Body	Action	Date
European Medicines Agency, Committee on Herbal Medicinal Products (HMPC) (European Union)	Final EU herbal monograph (revision 1, adopted 20 November 2024) for eucalyptus oil from Eucalyptus globulus, E. polybractea and E. smithii: traditional-use medicine for cough with a cold and localised muscle pain, based on long use only. Oral use from 12 years, inhalation and skin use with the age limits above. Contraindicated under 24 months and in children with seizures. source	2026-10-25
US Food and Drug Administration (21 CFR 172.515) (United States)	Lists "Eucalyptol; 1,8-epoxy-p-menthane; cineole" among synthetic flavouring substances and adjuvants that may be safely used in food under stated conditions. source	2026-10-25
ECHA C&L Inventory, via PubChem (company notifications) (European Union)	Companies notify 1,8-cineole mostly as a flammable liquid (H226) and a skin sensitiser (H317); 8 of 2,296 reports say it does not meet hazard criteria. source	2026-10-25

When to get medical help

A child has swallowed any eucalyptus oil, vaporiser fluid or chest rub: call a poison centre or emergency services at once, even if the child seems well. Do not make them vomit.
Seizure, fit or loss of consciousness after eucalyptus oil or balm was swallowed, rubbed on or breathed in.
Drowsiness, unsteadiness, slow or shallow breathing, coughing or choking after eucalyptus oil.
Swelling of the face or lips, widespread rash or trouble breathing after contact with eucalyptus oil or cineole.
A baby or toddler who coughs, goes pale or has trouble breathing after eucalyptus vapour or rub on the chest.

Stop using the product and contact a clinician or emergency service. In the US, Poison Control is 1-800-222-1222.

General information only, not medical advice. Ask a clinician or pharmacist before use, especially with medicines, in pregnancy or with a health condition. See the Natural Remedy Safety guide.

Frequently asked questions

What is eucalyptol?

Eucalyptol is the main scent compound of eucalyptus oil, also called 1,8-cineole or cineole (C10H18O). It is found in rosemary, bay laurel and sage oils and in some tea tree types, and it is reported in hemp and cannabis.

^{27 46 14 2}

Is eucalyptol the same as eucalyptus oil?

No. Eucalyptus oil is a mixture. In one E. globulus oil, 1,8-cineole was 63.1%, with p-cymene, alpha-pinene and limonene. Poisoning reports and EU rules are about the oil; capsule trials used purified cineole.

^{46 4}

Is there human research on eucalyptol?

Yes, more than for most terpenes: randomised trials of cineole capsules for COPD, asthma, bronchitis and sinusitis in adults. The main ones were funded by the maker (Cassella-med) and are single trials, mostly from one research group. There is no trial of eucalyptol from cannabis.

^{41 42 5 18}

Does it help with COPD or asthma?

In single trials cineole capsules added to usual treatment went with fewer COPD flare-ups and better asthma lung function and symptoms. Evidence is low certainty. A 2026 meta-analysis ranked cineole first for fewer flare-ups, but it is an indirect ranking. People should keep taking prescribed medicines and ask their doctor.

^{41 42 43}

Did every trial show benefit?

No. A double-blind trial of a three-terpene capsule (eucalyptol, limonene, pinene) added to a steroid nose spray missed its main goal at week 8 (p = 0.093). It is a mixture, not eucalyptol alone.

^{12 35}

Who paid for the research?

The COPD and bronchitis trials were funded by a grant from Cassella-med, which makes a cineole product. A 2024 cold trial was funded by Cassella-med and MCM Klosterfrau, and one review has an author employed by Cassella-med. For other trials the abstract does not state funding.

^{41 5 24 10}

Is eucalyptus oil dangerous if swallowed?

Yes, especially for small children. Hospital reports describe drowsiness, vomiting, unsteadiness and seizures; a children's hospital guideline says 5 mL or more of the pure oil can cause coma. Call a poison centre or emergency services at once if a child may have swallowed any.

^{39 38 6}

Is it safe for young children to breathe or have on the skin?

The EU herbal committee says eucalyptus oil medicines must not be used under 24 months because of laryngospasm, nor in children with seizures; inhalation under 3 years is listed as not established. Seizures have also been reported after eucalyptus vapour. Keep it away from small children.

^{4 22 29}

Is it safe in pregnancy?

Not known. The EU herbal committee says use in pregnancy and breastfeeding is not recommended because safety has not been established. Ask a doctor.

⁴

Does eucalyptol relieve pain or make cannabis work better?

Unknown. Rodent tests show less pain behaviour at large doses, one trial of smelling eucalyptus oil after knee surgery found lower pain scores, and a prediction model named eucalyptol as a key predictor of relief in cannabis users. None of this shows eucalyptol is the cause.

^{33 17 8}

Which cannabis strains have the most eucalyptol?

Our lab data hold no eucalyptol measurements, so we cannot rank strains. Some cannabis and hemp papers report it. The same strain name can have very different chemistry, so a lab report for the batch is the only guide.

^{44 45}

Can eucalyptol interact with medicines?

The EU herbal committee lists no reported interactions. In human liver tissue cineole is broken down mainly by CYP3A4, and in mice it lengthened sleeping time. Whether it changes other drug levels in people is unknown, so tell a doctor or pharmacist.

^{4 25 33}

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Editorial transparency

Written by: AlternativeMed editorial team. Research compiled with AI assistance, then checked against PubMed records.
Medical review: None. This page has not been reviewed by a physician or pharmacist.
First published: 2026-10-25
Last substantive update: 2026-10-25
How we research: We searched PubMed and read the abstracts of about 36 papers, read the EU herbal monograph on eucalyptus oil in full, read the US food-flavouring list through the eCFR, read PubChem for identity and hazard notifications, and read hospital and health-department guidance on eucalyptus oil poisoning through a page reader. We read two trial funding statements in full text. We say which sources we could not read.
How we rate evidence: See "How we rate evidence" in the Evidence tab.
Independence: No product is promoted on this page. No affiliate links are shown, and none will be added for eucalyptol. This page is information, not a recommendation to use it.

Sources 46

Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.

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Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.