Essential Oils & Aromatherapy · Essential oil
Manuka Oil
Leptospermum scoparium · also called manuka essential oil, mānuka oil, New Zealand tea tree
Manuka oil is the aromatic oil distilled from the leaves of the manuka shrub of New Zealand and Australia. It is not manuka honey. It is promoted for skin and germs, but the one controlled trial we found, a 2% cream for eczema, did no better than plain cream, and the germ-killing results come from dishes. The main caution: never swallow it, skin allergy is possible with essential oils, and no one has properly tested its toxicity.
General information, not medical advice. Last substantive update · Not medically reviewed. A named clinician has not signed off on this page. How this page is made
About Manuka Oil
Manuka oil is the sharp, herby oil from the leaves of a New Zealand and Australian shrub. Safety comes first: it should never be swallowed, essential oils can cause skin allergy (the data are for tea tree oil), and no one has properly tested its toxicity. The one controlled trial we found tested a manuka-oil cream for eczema and found no benefit over plain cream. Germ-killing results come from dishes.
What manuka oil is
Manuka oil is the essential oil of Leptospermum scoparium, in the myrtle family (Myrtaceae, per GBIF). A 2025 review says leaves of some Leptospermum species are used for essential oil. Papers use the spelling mānuka. Tea tree oil is from a different plant, Melaleuca alternifolia.
The oil is a mixture. One oil held 42% sesquiterpenes and three beta-triketones: leptospermone 17.2%, isoleptospermone 5.1% and flavesone 4.7%. A second commercial oil was 71.19% sesquiterpenes with leptospermone 17.44%. Makeup depends on where the plant grew.
A 2020 review says the plant has been used by the indigenous populations of New Zealand and Australia for centuries. We did not read Maori sources, and details of Maori practice belong to Maori to share. Manuka oil is not a food or a nutrient.
What people use it for, and how strong the evidence is
For skin, one single-blind trial in 118 adults with eczema found a cream with 2% of a manuka-oil-based product no better than plain cream over six weeks. The product's inventor is a shareholder of the company that funded the work, as declared.
For germs, dish studies show manuka oil stopping drug-resistant bacteria, food germs, a gum-disease bacterium and dog ear bacteria. A 2020 review calls the lab data extensive and the human data missing.
In a dish, the oil also killed scabies mites and eggs, and it killed cancer and normal cells. None of this is a treatment, and no human trial was found for these.
The research in one view
One human trial of a manuka-oil product was found, and it found no benefit. Everything else is cells, bacteria, mites or animal tissue in a dish or bath. Studies of manuka oil for acne, wounds, fungal skin problems, scent and sleep, pain or breathing were not found.
A 2026 correction notice exists for the scabies paper; its content was not available.
Manuka oil, manuka honey and tea tree oil are different things
Manuka honey comes from the nectar of Leptospermum flowers and is a separate product with its own research. Tea tree oil comes from a different plant, and many safety facts here are borrowed from it because manuka oil has so few studies.
In 2000 tests the three New Zealand and Australian 'tea tree' oils acted differently on muscle: manuka relaxed gut muscle while kanuka and tea tree first stimulated it. In a survey of 261 plants from 87 sites, oils differed by region, with a high-triketone type on the East Cape and ten other chemotypes elsewhere. A bottle may therefore differ from one in a study. No study of adulteration was found.
What regulators say
We did not find or read a statement from the FDA, EMA, NCCIH, IFRA or the EU cosmetics regulator about manuka essential oil. The eczema trial notes approval from the New Zealand Standing Committee on Therapeutic Trials, as required for trials of a new medicine; that is a trial approval, not a product approval.
A 2020 review itself says regulation, standardization and characterization are still needed.
At a glance
Traditional uses history, not proof
- A 2020 review says the plant has been used by the indigenous populations of New Zealand and Australia for centuries.
- A 2025 review of the whole Leptospermum genus lists traditional use for colds, fever, skin problems, pain and stomach disorders.
- No source read describes particular Maori practices; those belong to Maori to share.
Studied for research
- Eczema, 2% manuka-oil-based cream, against (no better than plain cream)
- Bacteria in dishes, insufficient
- Bacterial biofilm in dishes, insufficient
- Skin cell scratch closure in a dish, insufficient
- Scabies mites in a dish, insufficient
- Tumor cells in a dish (normal cells also died), insufficient
Main compounds
- Leptospermone, 17.2% of one manuka oil (a beta-triketone)
- Isoleptospermone, 5.1%, and flavesone, 4.7%, in the same oil
- Sesquiterpenes, 42% to 71% of the oils tested
Common forms
- Distilled leaf essential oil
- A 2% manuka-oil-based cream (one trial product)
- Scent in a room (not studied)
- Manuka honey is a different product
Research links: Eczema cream trial in New Zealand pharmacies (abstract) · Manuka oil review of antimicrobial properties (abstract) · Manuka oil against scabies mites in a dish (abstract) · Manuka oil chemotypes in New Zealand (abstract) · Tea tree oil poisoning in dogs and cats (abstract) · GBIF: Leptospermum scoparium · Research Library · Genes & Biomarkers Library
What it is and its history
- Accepted scientific name
- Leptospermum scoparium
- Naming authority
- J.R.Forst. & G.Forst. (GBIF writes Forst.)
- Common names
- manuka (English); manuka oil (English); New Zealand tea tree (English)
- Family or group
- Myrtaceae (myrtle family), order Myrtales, per GBIF.
- Classification
- Plantae > Tracheophyta > Myrtales > Myrtaceae > Leptospermum > Leptospermum scoparium
- Native range
- Not checked in a source read for this page; a review says Leptospermum is primarily native to Australia.
- Habitat
- Not described in the sources read.
- What it looks like
- Part used: A 2025 review says leaves of some Leptospermum species are used for essential oil. This page does not describe how to recognise the plant.
- Look-alikes and adulterants
- Name: Tea tree oil (Melaleuca alternifolia); Note: A different plant. Its oil has far more safety data and acts differently in tissue tests; do not assume manuka matches it.; Name: Kanuka / kunzea oil (Kunzea ericoides); Note: A New Zealand relative with its own oil; behaved differently from manuka oil in muscle and microbe tests (2000).; Name: Manuka honey; Note: Honey from the nectar of Leptospermum flowers. A different product with its own page.
- Sustainability and conservation
- Not checked (no IUCN or CITES source read).
Traditional use and history history, not clinical proof
| Tradition or era | Documented use | Source |
|---|---|---|
| Indigenous use in New Zealand and Australia | A 2020 review says the plant has been used by the indigenous populations of New Zealand and Australia for centuries. The review does not describe particular practices, and we did not read Maori sources. Details of Maori practice belong to Maori to share. | Mathew et al., Pharmaceuticals 2020 (abstract) |
| Genus traditional uses | A 2025 genus review lists traditional use for colds, fever, constipation, diarrhoea, skin problems, inflammation, stomach disorders and pain. These are for Leptospermum plants in general. | Hoang and Van Vuong, 2025 (abstract) |
Traditional use shows how it was used. It does not show that it 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 |
|---|---|---|---|---|
| Leptospermone PubChem 3083632 | beta-triketone | Leaf oil 17.2% of one manuka oil, 17.44% of another commercial manuka oil (two studies) | Killed scabies mites and eggs in a dish; the most potent triketone against eggs. 20 11 17 | Lab |
| Isoleptospermone PubChem 59518515 | beta-triketone | Leaf oil 5.1% of one manuka oil | Killed mites in a dish. 20 11 | Lab |
| Flavesone PubChem 15800949 | beta-triketone | Leaf oil 4.7% of one manuka oil | Altered tyrosine and fumarate levels in mites in a dish. 20 11 | Lab |
| Sesquiterpenes (group, including caryophyllene and humulene in some chemotypes) PubChem 5281515 | sesquiterpene hydrocarbons | Leaf oil 42% of one oil; 71.19% of another commercial oil | Did not track mite killing in the scabies study. 20 11 17 4 | Lab |
Mechanisms, receptors and pathways
| Target or pathway | Gene or receptor | What was found | Level |
|---|---|---|---|
| Tyrosine breakdown enzyme HPPD (in mites) | HPPD (4-hydroxyphenylpyruvate dioxygenase) | Mites exposed to flavesone had altered tyrosine and fumarate levels, and docking predicted triketones bind the mite enzyme. 11 | Laboratory and computer |
| Cell death signalling (JNK) in fibroblasts and fibrosarcoma cells | JNK, MKP-1, PARP | Manuka oil activated JNK as MKP-1 fell and triggered cell death in normal and cancer cells. 2 | Laboratory research |
| Bacterial biofilm and surface properties | Not specified | The oil lowered P. gingivalis hydrophobicity and inhibited biofilm by more than 85% at the MIC; docking suggested leptospermone and other metabolites bind virulence proteins. 17 | In vitro and computer |
| Smooth muscle (gut, uterus) | Not specified | Manuka oil relaxed guinea-pig gut and lowered the force of rat uterus contractions in a bath. 8 | Animal tissue |
Absorption, metabolism and elimination
- Absorption
- Not found for manuka oil.
- Distribution
- Not found.
- Metabolism
- Not found.
- Elimination
- Not found.
- Bioavailability
- Not established for manuka oil.
Isolated compounds versus whole extracts
Manuka oil is a mixture. In mite tests the triketones tracked the killing and the sesquiterpenes did not, so pure compounds and the whole oil can differ. Makeup changes with the plant's home region.
Nutritional composition
Manuka oil is not a food or a nutrient. Manuka honey is a different product made from nectar.
8 not enough evidence1 evidence against
What is Manuka Oil good for?
The uses people ask about and how strong the evidence is for each. Read the certainty label first: one trial found no benefit, and the rest is dish or tissue work.
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.
Eczema (a 2% manuka-oil-based cream)
Evidence againstIn 118 adults with moderate-to-severe eczema, a cream with 2% of a manuka-oil-based product worked no better than plain cream over six weeks. Both groups improved by the same amount.
1 studiesNot covered. This page gives no amounts and no way to use the oil.
Studies, doses and limits
What the trials found
One randomized, single-blind trial in 11 New Zealand pharmacies, registered as ACTRN12621001096842.
Results
Eczema score (POEM) fell from 16.3 to 8.8 with the oil cream and from 16.9 to 8.8 with plain cream; difference -0.38 (95% CI -2.58 to 1.82, p = 0.74). No secondary measure differed.
Effect sizes as reported
No difference from plain cream
Why this rating
A controlled human trial found no difference from plain cream. It tested one company's product, not plain oil, and it was single-blind. It was linked to the product's maker.
Form and dose studied
Not covered. This page gives no amounts and no way to use the oil.
Who was studied
Adults with moderate-to-severe eczema, New Zealand.
Limits
Six weeks; one product; industry-linked (company funding and inventor shareholder).
Why researchers looked
Skin products with botanical oils are popular for eczema, and manuka oil is marketed for skin.
Traditional use
No source read describes particular Maori practices. A 2020 review says the plant has been used by the indigenous peoples of New Zealand and Australia for centuries; that knowledge belongs to them and should be learned from them.
Proposed mechanism Preliminary mechanism
Not established.
A proposed mechanism does not show that the effect happens in people.
One cream, one trial. No serious adverse events were reported. Skin allergy, swallowing and pet cautions in the Safety tab apply to every use.
Slowing bacteria in a dish (manuka oil)
Not enough evidenceIn lab dishes, manuka oil stopped the growth of several drug-resistant bacteria, food-borne germs, a gum-disease bacterium and dog ear bacteria. A 2020 review calls the lab data extensive and says human studies are still needed.
4 studiesNot covered. This page gives no amounts and no way to use the oil.
Studies, doses and limits
What the trials found
No human trial of manuka oil against infection was found.
Results
Inhibition zones of 25 to 44 mm and MICs of 0.10 to 0.5 ug/mL against five multidrug-resistant species; MICs of 0.233 to 0.466 mg/mL for food-borne S. aureus and Listeria; the savory oil beat manuka oil against the gum-disease bacterium.
Effect sizes as reported
Bacteria blocked in dishes
Why this rating
All dish work. Strengths used in dishes may not be safe or reachable on skin, and the same oil harmed some human and mouse cells in other dish tests.
Form and dose studied
Not covered. This page gives no amounts and no way to use the oil.
Who was studied
Lab isolates; no people.
Limits
Different labs used different oils, bacteria and methods.
Why researchers looked
Antibiotic resistance has pushed researchers to look at plant oils.
Traditional use
No source read describes particular Maori practices. A 2020 review says the plant has been used by the indigenous peoples of New Zealand and Australia for centuries; that knowledge belongs to them and should be learned from them.
Proposed mechanism Preliminary mechanism
Lab studies point to damage of bacterial biofilms and cell surfaces. Not shown in people.
A proposed mechanism does not show that the effect happens in people.
Dish results do not show that the oil treats an infection. Skin allergy, swallowing and pet cautions in the Safety tab apply to every use.
Bacterial biofilms (food germs and a gum-disease germ, in dishes)
Not enough evidenceManuka oil reduced biofilm (the slimy layer germs build) in dishes. Against Staph aureus it cut biofilm by more than 50% at below-MIC strengths, but Listeria biofilm was not reduced and clearing existing biofilm took much stronger doses.
2 studiesNot covered. This page gives no amounts and no way to use the oil.
Studies, doses and limits
What the trials found
No human study found.
Results
Over 85% biofilm inhibition at the MIC against P. gingivalis; S. aureus biofilm reduction above 50% at half and a quarter of the MIC; Listeria not significantly reduced.
Effect sizes as reported
Mixed in dishes
Why this rating
Different germs gave different answers, all in dishes.
Form and dose studied
Not covered. This page gives no amounts and no way to use the oil.
Who was studied
Lab strains.
Limits
Two papers, two sets of bacteria.
Why researchers looked
Biofilms make germs harder to kill.
Traditional use
No source read describes particular Maori practices. A 2020 review says the plant has been used by the indigenous peoples of New Zealand and Australia for centuries; that knowledge belongs to them and should be learned from them.
Proposed mechanism Preliminary mechanism
Not established.
A proposed mechanism does not show that the effect happens in people.
Not tested as a mouth rinse or on teeth in people. Skin allergy, swallowing and pet cautions in the Safety tab apply to every use.
Skin cells closing a scratch (in a dish)
Not enough evidenceAt a very low concentration, human skin cells in a dish closed a scratch faster and showed no major DNA damage after 24 hours.
1 studiesNot covered. This page gives no amounts and no way to use the oil.
Studies, doses and limits
What the trials found
No human wound study of manuka oil was found.
Results
Total antioxidant status and scratch closure were higher at 0.008 ug/mL; no significant DNA damage at 24 h.
Effect sizes as reported
Faster scratch closure in a dish
Why this rating
A scratch in a cell dish is not a wound in a person.
Form and dose studied
Not covered. This page gives no amounts and no way to use the oil.
Who was studied
Human keratinocyte cell line.
Limits
One lab; 24 h only.
Why researchers looked
Wound healing is a common claim for manuka products, mostly for honey.
Traditional use
No source read describes particular Maori practices. A 2020 review says the plant has been used by the indigenous peoples of New Zealand and Australia for centuries; that knowledge belongs to them and should be learned from them.
Proposed mechanism Preliminary mechanism
Not established.
A proposed mechanism does not show that the effect happens in people.
Dish result at a very low concentration; higher strengths harmed cells in other dish studies. Skin allergy, swallowing and pet cautions in the Safety tab apply to every use.
Dog ear-infection bacteria (in a dish, with Tris-EDTA)
Not enough evidenceManuka oil with the helper Tris-EDTA stopped 53 bacterial isolates from dogs with ear infections in a dish, including multidrug-resistant ones.
1 studiesNot covered. This page gives no amounts and no way to use the oil.
Studies, doses and limits
What the trials found
No clinical study in dogs was found.
Results
Oil alone MIC at least 1% and MBC at least 2% (v/v); with Tris-EDTA MICs 0.06 to 0.5% and MBCs 0.06 to 1% (P < 0.001).
Effect sizes as reported
Bacteria blocked in a dish
Why this rating
Dish work on isolates; the authors want clinical and hearing-safety studies.
Form and dose studied
Not covered. This page gives no amounts and no way to use the oil.
Who was studied
53 dog isolates.
Limits
Dish work.
Why researchers looked
Ear infections in dogs are often resistant to drugs.
Traditional use
No source read describes particular Maori practices. A 2020 review says the plant has been used by the indigenous peoples of New Zealand and Australia for centuries; that knowledge belongs to them and should be learned from them.
Proposed mechanism Preliminary mechanism
Not established.
A proposed mechanism does not show that the effect happens in people.
Not tested in animals; ear safety (ototoxicity) is unknown per the authors. Do not put oils in a pet's ears without a vet.
Scabies mites and eggs (in a dish)
Not enough evidenceIn a dish, manuka oil and its triketones killed scabies mites and eggs more strongly than ivermectin, permethrin, kunzea oil and tea tree oil. This does not show it can treat scabies on a person.
2 studiesNot covered. This page gives no amounts and no way to use the oil.
Studies, doses and limits
What the trials found
No human scabies trial found.
Results
Oil held 42% sesquiterpenes, leptospermone 17.2%, isoleptospermone 5.1% and flavesone 4.7%. Triketones, not sesquiterpenes, tracked the killing.
Effect sizes as reported
Mites and eggs killed in a dish
Why this rating
Dish work only, with a 2026 correction notice whose content was not read.
Form and dose studied
Not covered. This page gives no amounts and no way to use the oil.
Who was studied
Mites in a dish.
Limits
No skin or safety test; the oil was supplied by a company, which had no role in the study.
Why researchers looked
Scabies is hard to treat in some places, and Australasian plant oils kill parasites.
Traditional use
No source read describes particular Maori practices. A 2020 review says the plant has been used by the indigenous peoples of New Zealand and Australia for centuries; that knowledge belongs to them and should be learned from them.
Proposed mechanism Preliminary mechanism
The triketones may block a mite enzyme (HPPD): shown by changed mite chemistry and computer docking, not in people.
A proposed mechanism does not show that the effect happens in people.
Not tested on skin or in people. Do not treat scabies with oils; see a doctor. Skin allergy, swallowing and pet cautions in the Safety tab apply to every use.
Killing cancer cells (in a dish)
Not enough evidenceManuka oil killed fibrosarcoma (a cancer) cells in a dish, but it also killed normal fibroblasts. It is not a cancer treatment.
2 studiesNot covered. This page gives no amounts and no way to use the oil.
Studies, doses and limits
What the trials found
No human study found.
Results
Growth and viability fell with higher concentrations in all cell lines; PARP cleavage showed apoptosis in both normal and cancer cells.
Effect sizes as reported
Cell death in a dish, not selective
Why this rating
Dish work; not selective for cancer cells.
Form and dose studied
Not covered. This page gives no amounts and no way to use the oil.
Who was studied
Cell lines.
Limits
One lab; 24 h.
Why researchers looked
Plant oils are often screened for anti-cancer effects.
Traditional use
No source read describes particular Maori practices. A 2020 review says the plant has been used by the indigenous peoples of New Zealand and Australia for centuries; that knowledge belongs to them and should be learned from them.
Proposed mechanism Preliminary mechanism
Activated a stress-signal protein, JNK, and triggered cell death (apoptosis).
A proposed mechanism does not show that the effect happens in people.
Not a treatment. The oil also killed normal cells. Do not use oils for cancer.
Muscle and uterus tissue in a bath (animal tissue)
Not enough evidenceIn animal tissue, manuka oil relaxed gut muscle and lowered the force of rat womb contractions. The authors say this suggests caution in childbirth.
1 studiesNot covered. This page gives no amounts and no way to use the oil.
Studies, doses and limits
What the trials found
No human study found.
Results
Manuka relaxed guinea-pig gut; all three oils lowered the force of spontaneous rat uterus contractions.
Effect sizes as reported
Contractions lowered in tissue
Why this rating
Old animal tissue work (2000); not a benefit.
Form and dose studied
Not covered. This page gives no amounts and no way to use the oil.
Who was studied
Animal tissue.
Limits
Animal tissue; no people.
Why researchers looked
Aromatherapists use tea-tree-type oils, and the authors wanted a basic check of their action.
Traditional use
No source read describes particular Maori practices. A 2020 review says the plant has been used by the indigenous peoples of New Zealand and Australia for centuries; that knowledge belongs to them and should be learned from them.
Proposed mechanism Preliminary mechanism
Action on smooth and skeletal muscle in a bath; not shown in people.
A proposed mechanism does not show that the effect happens in people.
Authors suggest caution in childbirth. Pregnancy section in the Safety tab applies.
Other claims for the Leptospermum plant group (anti-diabetes, anti-Alzheimer's, others)
Not enough evidenceA 2025 review of the whole Leptospermum genus lists early lab links to antimicrobial, antidiabetes, anticancer and anti-Alzheimer's activity. It is not about manuka oil in people.
1 studiesNot covered. This page gives no amounts and no way to use the oil.
Studies, doses and limits
What the trials found
No human trial of manuka oil for these uses was found.
Results
Review abstract gives no data.
Effect sizes as reported
Preliminary only
Why this rating
A genus review with no data in the abstract.
Form and dose studied
Not covered. This page gives no amounts and no way to use the oil.
Who was studied
None.
Limits
Genus-level; may include extracts, not oil.
Why researchers looked
People search for wider health uses of manuka.
Traditional use
No source read describes particular Maori practices. A 2020 review says the plant has been used by the indigenous peoples of New Zealand and Australia for centuries; that knowledge belongs to them and should be learned from them.
Proposed mechanism Preliminary mechanism
Not established.
A proposed mechanism does not show that the effect happens in people.
Claims for the genus, not shown for manuka oil.
Connections to the rest of health
How Manuka Oil 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
A. Wellness goals
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Healthy Skin | Evidence against | Eczema (a 2% manuka-oil-based cream): In 118 adults with moderate-to-severe eczema, a cream with 2% of a manuka-oil-based product worked no better than plain cream over six weeks. Both groups improved by the same amount. | 14 | |
| Infection Support | Not enough evidence | Slowing bacteria in a dish (manuka oil): In lab dishes, manuka oil stopped the growth of several drug-resistant bacteria, food-borne germs, a gum-disease bacterium and dog ear bacteria. A 2020 review calls the lab data extensive and says human studies are still needed. Bacterial biofilms (food germs and a gum-disease germ, in dishes): Manuka oil reduced biofilm (the slimy layer germs build) in dishes. Against Staph aureus it cut biofilm by more than 50% at below-MIC strengths, but Listeria biofilm was not reduced and clearing existing biofilm took much stronger doses. | 3 17 13 9 15 | |
| Oral Health | Not enough evidence | Bacterial biofilms (food germs and a gum-disease germ, in dishes): Manuka oil reduced biofilm (the slimy layer germs build) in dishes. Against Staph aureus it cut biofilm by more than 50% at below-MIC strengths, but Listeria biofilm was not reduced and clearing existing biofilm took much stronger doses. | 17 13 | |
| Healthy Skin | Not enough evidence | Skin cells closing a scratch (in a dish): At a very low concentration, human skin cells in a dish closed a scratch faster and showed no major DNA damage after 24 hours. Scabies mites and eggs (in a dish): In a dish, manuka oil and its triketones killed scabies mites and eggs more strongly than ivermectin, permethrin, kunzea oil and tea tree oil. This does not show it can treat scabies on a person. | 3 11 12 | |
| Insect Protection | Not enough evidence | Scabies mites and eggs (in a dish): In a dish, manuka oil and its triketones killed scabies mites and eggs more strongly than ivermectin, permethrin, kunzea oil and tea tree oil. This does not show it can treat scabies on a person. | 11 12 | |
| Cancer Research | Not enough evidence | Killing cancer cells (in a dish): Manuka oil killed fibrosarcoma (a cancer) cells in a dish, but it also killed normal fibroblasts. It is not a cancer treatment. | 2 6 | |
| Womens Wellness | Not enough evidence | Muscle and uterus tissue in a bath (animal tissue): In animal tissue, manuka oil relaxed gut muscle and lowered the force of rat womb contractions. The authors say this suggests caution in childbirth. | 8 | |
| Metabolic Health | Not enough evidence | Other claims for the Leptospermum plant group (anti-diabetes, anti-Alzheimer's, others): A 2025 review of the whole Leptospermum genus lists early lab links to antimicrobial, antidiabetes, anticancer and anti-Alzheimer's activity. It is not about manuka oil in people. | 6 | |
| Brain Health | Not enough evidence | Other claims for the Leptospermum plant group (anti-diabetes, anti-Alzheimer's, others): A 2025 review of the whole Leptospermum genus lists early lab links to antimicrobial, antidiabetes, anticancer and anti-Alzheimer's activity. It is not about manuka oil in people. | 6 |
B. Body systems
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Integumentary System | Biological association | Evidence against | Studied for: Eczema (a 2% manuka-oil-based cream) Studied for: Skin cells closing a scratch (in a dish) | 14 3 11 12 |
| Immune System | Biological association | Not enough evidence | Studied for: Slowing bacteria in a dish (manuka oil) Studied for: Bacterial biofilms (food germs and a gum-disease germ, in dishes) | 3 17 13 9 15 |
| Cells | Biological association | Not enough evidence | Studied for: Killing cancer cells (in a dish) | 2 6 |
| Reproductive System | Biological association | Not enough evidence | Studied for: Muscle and uterus tissue in a bath (animal tissue) | 8 |
| Whole Body | Biological association | Not enough evidence | Studied for: Other claims for the Leptospermum plant group (anti-diabetes, anti-Alzheimer's, others) | 6 |
E. Health conditions
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Contact dermatitis | Related oil risk | Tea tree oil is a leading cause of published essential-oil allergy; manuka oil not tested. Preparation or compound: Essential oils on skin (data for tea tree oil) |
18 16 | |
| Eczema | Evidence against | No difference from plain cream in 118 adults. Preparation or compound: 2% manuka-oil-based cream |
14 |
I. Biomarkers
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Eczema symptom score (POEM) | Biological association | Low certainty | Measured in trials: decrease. A lab change is not the same as a health benefit. | 14 |
| Minimum inhibitory and bactericidal concentration (MIC, MBC) | Biological association | Not enough evidence | Measured in trials: decrease. A lab change is not the same as a health benefit. | 3 13 15 |
| Skin cell scratch closure and DNA damage | Biological association | Not enough evidence | Measured in trials: increase. A lab change is not the same as a health benefit. | 3 |
| Mite kill (LC50) and egg hatching | Biological association | Not enough evidence | Measured in trials: decrease. A lab change is not the same as a health benefit. | 11 |
| Cell viability and PARP cleavage | Biological association | Not enough evidence | Measured in trials: decrease. A lab change is not the same as a health benefit. | 2 |
K. Biological pathways
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| JNK stress signalling and apoptosis | Preliminary mechanism | In vitro | Activated in cell lines treated with manuka oil. | 2 |
L. Active compounds
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Leptospermone | Biological association | Lab | Killed scabies mites and eggs in a dish; the most potent triketone against eggs. Preparation or compound: Leaf oil |
20 11 17 |
| Isoleptospermone | Biological association | Lab | Killed mites in a dish. Preparation or compound: Leaf oil |
20 11 |
| Flavesone | Biological association | Lab | Altered tyrosine and fumarate levels in mites in a dish. Preparation or compound: Leaf oil |
20 11 |
| Sesquiterpenes (group, including caryophyllene and humulene in some chemotypes) | Biological association | Lab | Did not track mite killing in the scabies study. Preparation or compound: Leaf oil |
20 11 17 4 |
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).
The evidence
The research centre for Manuka Oil. Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.
Evidence by outcome
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 read the abstracts of 18 PubMed records, checked plant names in GBIF and compounds in PubChem. Tea tree oil data are labelled as a related oil. We did not read a LiverTox, LactMed, IFRA or FDA statement.
Study library: every study we checked 20
| Study | Design | People | Product, dose, length | Result |
|---|---|---|---|---|
| Barbaud 2023 Allergic contact dermatitis from essential oil in consumer products: Mode of uses and value of patch tests with an essential oil series. Results of a French study of the DAG (Dermato-Allergology group of the French Society of Dermatology). Contact Dermatitis · PMID 37403438 · DOI |
Clinic case series |
42 42 patients with allergic contact dermatitis from their own essential oils (France) |
Essential oils used by patients, mainly lavender, tea tree, ravintsara; helichrysum in 2 cases oils on skin Not given here n/a · vs n/a |
All 42 patients were sensitized to the oil they used; 8 needed hospital care. 40% did not mention essential oil use on their own, and only 33% had received advice when buying. The authors say testing the patient's own oil is most important. Allergy from home use; hospital care in 8 Methods, limits and fundingOutcomes: Patch tests, mode of use Limitations: Manuka oil was not named in the abstract. Funding and conflicts: Not reported in the abstract. Read: abstract |
| Bass 2024 Manuka Essential Oil Triggers Apoptosis and Activation of c-Jun N-Terminal Kinase in Fibroblasts and Fibrosarcoma Cells. Molecules · PMID 39519810 · DOI |
Laboratory study (cells) lab |
Normal fibroblast cells (CUA-4) and fibrosarcoma cells (HT-1080) in a dish | Manuka essential oil at several concentrations essential oil Not given here 24 h · vs Untreated cells |
As the concentration rose, growth and viability fell in all cell lines tested. PARP cleavage showed the oil triggered cell death (apoptosis) in both the normal fibroblasts and the cancer cells. A stress-signal protein, JNK, was activated. Cells died in a dish, normal cells too Methods, limits and fundingOutcomes: Cell counts, MTT viability, PARP cleavage (a cell-death marker), JNK signalling Limitations: Dish work; the oil harmed normal cells as well as cancer cells, so it shows no safe selective effect. Funding and conflicts: No conflicts of interest declared. Read: abstract |
| Bučková 2026 Leptospermum scoparium Essential Oil: Antibacterial Properties, Cyto/Genotoxic Effects, Antioxidant Activity, and Wound-Healing Potential In Vitro. Molecules · PMID 42796590 · DOI |
Laboratory study (cells and bacteria) lab |
Human skin cell line (HaCaT keratinocytes) and multidrug-resistant bacterial isolates | Manuka (Leptospermum scoparium) essential oil essential oil Not given here 24 h cell treatment; bacterial tests · vs Untreated cells / controls |
No significant DNA damage in the skin cells after 24 h. At 0.008 ug/mL the oil raised total antioxidant status and sped scratch closure. Against P. aeruginosa, P. vulgaris, E. coli, E. cloacae and S. aureus (multidrug-resistant isolates) inhibition zones were 25 to 44 mm; MIC 0.10 to 0.5 ug/mL and MBC 0.25 to 0.75 ug/mL. Germ growth blocked and scratch closure faster in a dish Methods, limits and fundingOutcomes: DNA damage, antioxidant status, scratch closure, inhibition zones, MIC and MBC Limitations: Cells and bacteria in a dish; not a wound in a person. The abstract does not give the oil's makeup. Funding and conflicts: No conflicts of interest declared. Read: abstract |
| Douglas 2004 Essential oils from New Zealand manuka: triketone and other chemotypes of Leptospermum scoparium. Phytochemistry · PMID 15184010 · DOI |
Chemical survey of plants plants |
261 261 individual manuka plants from 87 sites in New Zealand |
Manuka (Leptospermum scoparium) essential oils oil from plants Not given here Seasonal variation checked in 36 East Cape plants · vs n/a |
Oils from 36 East Cape plants all had high triketone content (more than 20% total triketones) with little seasonal variation. The high-triketone type was localised on the East Cape, with up to 20% in the Marlborough Sounds. Ten further chemotypes were described (including alpha-pinene, geranyl acetate, high linalol and several sesquiterpene-rich types). Oil makeup differs strongly by place Methods, limits and fundingOutcomes: Oil composition, chemotypes Limitations: 2004 survey of plants, not a safety or benefit study. Funding and conflicts: Not reported in the abstract. Read: abstract |
| Hawkins 2020 The relationship between lavender and tea tree essential oils and pediatric endocrine disorders: A systematic review of the literature. Complement Ther Med · PMID 32147050 · DOI |
Systematic review of case reports |
Prepubertal children with breast enlargement (gynecomastia) or early breast development (premature thelarche) | Lavender and tea tree essential oils on skin oil Not given here n/a · vs n/a |
Found four papers describing eleven cases. Reporting was insufficient. The review found no evidence supporting a link for tea tree oil and little to none for lavender oil, and calls for epidemiological research. No supported link found Methods, limits and fundingOutcomes: Link between the oils and early breast development Limitations: Tea tree and lavender, not manuka. No source on manuka was found. Funding and conflicts: No conflicts declared. Read: abstract |
| Hoang 2025 A Comprehensive Review of the Botany, Bioactive Compounds and Health Benefits of Leptospermum. Chem Biodivers · PMID 39599991 · DOI |
Narrative review review |
Plants of the genus Leptospermum | Leptospermum oils and extracts (many species) oil and extracts Not given here n/a · vs n/a |
Says the genus has been used traditionally for colds, fever, constipation, diarrhoea, skin problems, inflammation, stomach disorders and pain. Says manuka honey comes from the nectar of Leptospermum flowers and that leaves of some species are used for essential oil. Preliminary studies link oils and extracts to antimicrobial, antidiabetes, anticancer and anti-Alzheimer's activity. Preliminary only Methods, limits and fundingOutcomes: Botany, compounds and health claims for the genus Limitations: Covers the whole genus, not manuka oil alone; the abstract gives no data. Funding and conflicts: Not reported in the abstract. Read: abstract |
| Khan 2014 Concentrated tea tree oil toxicosis in dogs and cats: 443 cases (2002-2012). J Am Vet Med Assoc · PMID 24344857 · DOI |
Retrospective case series (poison centre data) animal |
443 337 dogs and 106 cats exposed to 100% tea tree oil, US and Canada |
100% tea tree oil (Melaleuca alternifolia, a different plant from manuka) oil Not given here Signs within 2 to 12 hours, lasting up to 72 hours · vs n/a |
Exposure was on the skin in 50%, skin and mouth in 30% and mouth only in 15%. Signs began within 2 to 12 hours and lasted up to 72 hours: drooling, CNS depression or lethargy, weakness (paresis), unsteady walking (ataxia) and tremors. Younger, smaller cats were more likely to be seriously ill. Serious signs from concentrated tea tree oil Methods, limits and fundingOutcomes: Signs, severity, outcome Limitations: Tea tree oil, not manuka oil; no manuka pet data were found. Funding and conflicts: Not reported in the abstract. Read: abstract |
| Lis-Balchin 2000 Pharmacological and antimicrobial studies on different tea-tree oils (Melaleuca alternifolia, Leptospermum scoparium or Manuka and Kunzea ericoides or Kanuka), originating in Australia and New Zealand. Phytother Res · PMID 11114000 · DOI |
Laboratory study (animal tissue and microbes) animal tissue |
Guinea-pig gut, chick and rat muscle, rat uterus (tissue in a bath), and microbes | Manuka, kanuka (Kunzea ericoides) and Australian tea tree (Melaleuca alternifolia) oils essential oil Not given here Lab bath tests · vs Each other |
Manuka oil relaxed gut muscle, while kanuka and tea tree first stimulated it. All three oils lowered the force of spontaneous rat-uterus contractions; the authors say this suggests caution during childbirth. Manuka samples varied more than tea tree samples in antimicrobial activity. The authors note only tea tree had been tested for toxicity. Tissue effects in a bath; large sample variation Methods, limits and fundingOutcomes: Smooth and skeletal muscle action, uterus contractions, antimicrobial and antioxidant activity Limitations: From 2000; animal tissue, not people. Funding and conflicts: Not reported in the abstract. Read: abstract |
| Mathew 2020 Mānuka Oil-A Review of Antimicrobial and Other Medicinal Properties. Pharmaceuticals (Basel) · PMID 33114724 · DOI |
Narrative review review |
Published and grey-literature sources up to June 2020 | Manuka oil and its components essential oil Not given here n/a · vs n/a |
Found extensive in vitro data supporting antimicrobial effects that warrants further clinical studies. Says clinical evidence on efficacy, safety and dosing guidelines is necessary, and that regulation, standardization and characterization are required. States the plant has been used by indigenous populations of New Zealand and Australia for centuries. Lab data extensive; clinical data missing Methods, limits and fundingOutcomes: Antimicrobial, anti-parasitic and anti-inflammatory activity; safety and dosing evidence Limitations: Narrative review, not a graded systematic review. One author is affiliated with a New Zealand herbal company, Phytomed Medicinal Herbs Ltd. Funding and conflicts: Authors declare no conflicts of interest; one author is affiliated with Phytomed Medicinal Herbs Ltd. Read: abstract |
| Morris 2003 Ingestion of tea tree oil (Melaleuca oil) by a 4-year-old boy. Pediatr Emerg Care · PMID 12813303 · DOI |
Case report |
1 A 4-year-old boy |
Tea tree oil (Melaleuca oil), swallowed oil Not given here n/a · vs n/a |
Within 30 minutes he was unsteady (ataxic) and soon unresponsive, and paramedics put in a breathing tube. His nervous system improved over 10 hours and he was well at follow-up. Swallowed tea tree oil caused unconsciousness Methods, limits and fundingOutcomes: Effects of a small swallowed amount Limitations: One child; tea tree oil, not manuka oil. Funding and conflicts: Not reported in the abstract. Read: abstract |
| Nammunige 2025 β-Triketones from Leptospermum scoparium (mānuka) oil show potential as scabicides. Phytomedicine · PMID 39752786 · DOI |
Laboratory study (mites and eggs) lab |
Scabies mites (Sarcoptes scabiei) and eggs in a dish; computer docking | Manuka essential oil, three beta-triketones (flavesone, leptospermone, isoleptospermone), compared with tea tree and kunzea oils, ivermectin and permethrin essential oil and pure compounds Not given here Mite survival at 4 h; egg hatching · vs Conventional scabies drugs and other oils |
Manuka oil killed mites and eggs more strongly than ivermectin, permethrin, kunzea oil and tea tree oil in these dish tests. The oil held 42% sesquiterpenes and three triketones: flavesone 4.7%, leptospermone 17.2%, isoleptospermone 5.1%. Killing correlated with the triketones, not the sesquiterpenes. Mite tyrosine and fumarate levels changed, and docking suggested the triketones block a mite enzyme (HPPD). Mites and eggs killed in a dish Methods, limits and fundingOutcomes: Mite killing, egg hatching, mite tyrosine and fumarate, enzyme docking Limitations: Dish work only; no skin, safety or human test. A corrigendum (PMID 41832089) was published in 2026 and its content was not read in full (the abstract record has no text). Funding and conflicts: The oil was supplied by Phytomed Medicinal Herbs Ltd, which the authors state had no role in design, analysis or publication. Read: abstract |
| Nammunige 2026 Corrigendum to "β-Triketones from Leptospermum scoparium (mānuka) oil show potential as scabicides" [Phytomedicine Volume 136, January 2025, 156321]. Phytomedicine · PMID 41832089 · DOI |
Published erratum (corrigendum) n/a |
n/a | n/a n/a Not given here n/a · vs n/a |
The PubMed record has no abstract. The correction itself was not read. Not known Methods, limits and fundingOutcomes: Correction notice for PMID 39752786 Limitations: Content of the correction unknown. Read: abstract |
| Pedonese 2022 Antimicrobial and anti-biofilm activity of manuka essential oil against Listeria monocytogenes and Staphylococcus aureus of food origin. Ital J Food Saf · PMID 35284338 · DOI |
Laboratory study (food bacteria) lab |
Listeria monocytogenes (7 strains) and Staphylococcus aureus (7 strains, 5 methicillin-resistant) of food origin | Manuka essential oil essential oil Not given here Standard lab tests · vs Untreated controls |
L. monocytogenes MIC 0.466 mg/mL and MBC 0.933 mg/mL; S. aureus MIC 0.233 mg/mL and MBC 0.466 mg/mL. Biofilm eradication needed 0.933 to 1.865 mg/mL for Listeria and 14.922 mg/mL for S. aureus. Listeria biofilm was not significantly reduced at below-MIC strengths; S. aureus biofilm fell by more than 50% at half and a quarter of the MIC. Bacteria and biofilms affected in a dish Methods, limits and fundingOutcomes: MIC, MBC, biofilm inhibition and eradication Limitations: Food-industry lab test; says nothing about use on the body. Funding and conflicts: Not reported in the abstract. Read: abstract |
| Shortt 2026 Randomised controlled trial of mānuka oil-based ECMT-154™ vs. vehicle control for the topical treatment of eczema, conducted in community pharmacies in New Zealand. BMC Complement Med Ther · PMID 41629897 · DOI |
Randomized trial, single blind, two groups |
118 Adults with moderate-to-severe eczema in 11 community pharmacies, New Zealand |
Cream containing 2% of a manuka-oil-based product called ECMT-154 (one company's product, not plain oil) cream Not given here Twice daily for six weeks · vs Plain cream (vehicle control) |
POEM fell from 16.3 (SD 4.2) to 8.8 (SD 5.7) with the manuka-oil cream and from 16.9 (SD 3.8) to 8.8 (SD 5.7) with plain cream; between-group difference -0.38 (95% CI -2.58 to 1.82, p = 0.74). No significant differences on any secondary measure. No serious adverse events were reported. No difference from plain cream Methods, limits and fundingOutcomes: Patient Oriented Eczema Measure (POEM) at week 6; secondary eczema measures; adverse events Limitations: Single-blind, one product, six weeks. The inventor of the product is a shareholder of the company; the company funded the research institute for the work (as declared). The paper says the inventor had input into the protocol but not the running or analysis of the trial. Funding and conflicts: Industry-linked: funding to the research institute from Manuka Bioscience; the product's inventor is a company shareholder. Registration: ACTRN12621001096842 Read: abstract |
| Song 2020 In vitro antibacterial activity of the manuka essential oil from Leptospermum scoparium combined with Tris-EDTA against Gram-negative bacterial isolates from dogs with otitis externa. Vet Dermatol · PMID 31729809 · DOI |
Laboratory study (dog ear bacteria) lab |
53 Gram-negative bacterial isolates from dogs with ear infection (otitis externa) | Manuka essential oil, with and without Tris-EDTA essential oil Not given here Standard lab tests · vs Tris-EDTA alone |
Manuka oil alone: MIC at least 1% and MBC at least 2% (v/v). Tris-EDTA alone had no effect. Together they lowered MICs to 0.06% to 0.5% and MBCs to 0.06% to 1% (P < 0.001), including in multidrug-resistant isolates. The authors say clinical studies are needed to check for harm to the ear (ototoxicity) and for effect. Bacteria blocked in a dish, more with a helper Methods, limits and fundingOutcomes: MIC and MBC Limitations: Dish work on dog isolates; ear safety unknown. Funding and conflicts: Not reported in the abstract. Read: abstract |
| Warshaw 2017 Positive Patch-Test Reactions to Essential Oils in Consecutive Patients From North America and Central Europe. Dermatitis · PMID 28614106 · DOI |
Retrospective patch test analysis |
62354 Consecutive patients tested in North American (NACDG) and central European (IVDK) clinics |
Oils in the baseline patch-test series, including oxidized tea tree oil 5% patch test Not given here 2009 to 2014 data · vs n/a |
11,568 of 62,354 patients (18.6%) reacted to a fragrance marker or essential oil. Among patients reacting to an essential oil but none of the fragrance markers, tea tree oil (Melaleuca alternifolia) gave the most positives in North America (45%); about half were strong and of probable relevance. Positive rates for individual oils included tea tree 0.3%, peppermint 0.9%, lavender 0.3%. Essential oils cause contact allergy Methods, limits and fundingOutcomes: Positive patch-test reactions Limitations: Manuka oil was not among the oils tested. Funding and conflicts: Not reported in the abstract. Read: abstract |
| Yuan 2025 Investigation of differential Multi-Mode antibacterial mechanisms of essential oils of Satureja montana L. and Leptospermum scoparium J.R.Forst. & G.Forst. Against Porphyromonas gingivalis. BMC Complement Med Ther · PMID 40696347 · DOI |
Laboratory study (bacteria and cells) lab |
Porphyromonas gingivalis (gum-disease bacterium) in a dish; mouse macrophage cell line | Commercial manuka (Leptospermum scoparium) essential oil, compared with a savory (Satureja montana) oil essential oil Not given here Standard lab tests · vs Another essential oil; controls |
Manuka oil blocked the bacterium (zone 40.36 mm, MIC 305 ug/mL, MBC 1220 ug/mL) but less strongly than the savory oil (MIC 71.33 ug/mL). Biofilm inhibition exceeded 85% at the MIC for both oils. The manuka oil was 71.19% sesquiterpenes with leptospermone 17.44%. At the MIC, mouse cell viability was 68.81% (86.68% for the savory oil). Bacteria blocked in a dish; some cells harmed at the same strength Methods, limits and fundingOutcomes: Zone of inhibition, MIC, MBC, biofilm, hydrophobicity, virulence genes, cell viability at the MIC Limitations: One commercial oil in a dish; the authors describe their findings as a theoretical foundation. Cell viability fell to about 69% at the MIC. Funding and conflicts: No competing interests declared. Read: abstract |
| de Groot 2016 Tea tree oil: contact allergy and chemical composition. Contact Dermatitis · PMID 27173437 · DOI |
Narrative review review |
Published reports of contact allergy to tea tree oil | Tea tree oil (Melaleuca alternifolia) oil Not given here n/a · vs n/a |
Says tea tree oil has caused more published allergic reactions than any other essential oil. Positive patch-test rates ranged from 0.1% to 3.5% in routine testing; nearly 100 allergic patients were described. Fresh oil is a weak to moderate sensitizer and oxidation raises the risk. Most reactions came from pure oil. Co-reactivity to turpentine oil is frequent. Allergy common with pure tea tree oil Methods, limits and fundingOutcomes: Allergy frequency and chemical makeup Limitations: Tea tree oil, not manuka oil; no review of manuka oil allergy was found. Funding and conflicts: Not reported in the abstract. Read: abstract |
| n/a 2026 GBIF Backbone Taxonomy: Leptospermum scoparium Forst. (match API read 2026-10-25) n/a · Source |
Registry or database n/a |
n/a | n/a n/a n/a n/a · vs n/a |
Accepted species name Leptospermum scoparium Forst., status ACCEPTED, family Myrtaceae, order Myrtales, genus Leptospermum, exact match, no synonym flag. Methods, limits and fundingOutcomes: Accepted name and family Read: full-text |
| n/a 2026 PubChem: leptospermone (CID 3083632), isoleptospermone (CID 59518515), flavesone (CID 15800949), beta-caryophyllene (CID 5281515) (read 2026-10-25) n/a · Source |
Registry or database n/a |
n/a | n/a n/a n/a n/a · vs n/a |
PubChem lists leptospermone C15H22O4, isoleptospermone C15H22O4, flavesone C14H20O4 and caryophyllene C15H24. Methods, limits and fundingOutcomes: Compound identifiers Read: full-text |
What we do not know yet
- What the evidence supports: one trial of a 2% manuka-oil cream found no benefit for eczema; germ-killing, mite-killing and cell results are from dishes.
- No toxicity, poisoning, patch-test, pet, pregnancy or breastfeeding study of manuka oil was found; tea tree oil data are used and labelled.
- No human trial of plain manuka oil for any use was found.
- No adulteration study of manuka oil was found.
- No LiverTox, LactMed, IFRA or regulator statement was 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 is added.
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 5
Eczema symptom score (POEM)
Decrease in trials
A patient-filled questionnaire about itch, sleep, bleeding and other eczema effects; lower means fewer symptoms.
Low certaintyResults and what it means
Why it was measured
Primary outcome of the eczema cream trial.
Statistical vs. clinical meaning
Both groups improved the same, so the improvement cannot be credited to the oil.
Safety implication
A symptom score does not measure safety; no serious adverse events were reported.
| Study | Result | People | Product |
|---|---|---|---|
| 14 | Fell to 8.8 in both groups; the difference between oil cream and plain cream was -0.38 (95% CI -2.58 to 1.82). |
Minimum inhibitory and bactericidal concentration (MIC, MBC)
Decrease in trials
The lowest strength of a substance that stops (MIC) or kills (MBC) bacteria in a dish.
Not enough evidenceResults and what it means
Why it was measured
Standard lab measure of germ-killing in the dish studies.
Statistical vs. clinical meaning
Different units and methods in each lab, so the numbers cannot be compared across papers. A dish result does not show a result in a person.
Safety implication
The dish strengths say nothing about safe use.
Skin cell scratch closure and DNA damage
Increase in trials
How fast a gap closes in a layer of cultured skin cells, and whether the cells' DNA is damaged.
Not enough evidenceResults and what it means
Why it was measured
Used as a stand-in for wound healing in the Molecules 2026 study.
Statistical vs. clinical meaning
One lab, cell line only.
Safety implication
Other dish studies show the oil can kill human and animal cells at higher strengths.
| Study | Result | People | Product |
|---|---|---|---|
| 3 | Faster closure at 0.008 ug/mL; no significant DNA damage after 24 h. |
Mite kill (LC50) and egg hatching
Decrease in trials
The strength that kills half of the mites in a set time, and the share of eggs that still hatch.
Not enough evidenceResults and what it means
Why it was measured
Primary outcomes of the scabies dish study.
Statistical vs. clinical meaning
Mites in a dish, no skin barrier.
Safety implication
Says nothing about skin safety.
| Study | Result | People | Product |
|---|---|---|---|
| 11 | Triketone LC50 58.6 to 61.7 mM at 4 h; oil killed mites more strongly than ivermectin, permethrin, kunzea and tea tree oil in the dish. |
Cell viability and PARP cleavage
Decrease in trials
How many cells survive treatment, and a marker (PARP cleavage) showing programmed cell death.
Not enough evidenceResults and what it means
Why it was measured
Outcomes of the fibroblast and fibrosarcoma study.
Statistical vs. clinical meaning
Dish work; non-selective.
Safety implication
Shows the oil can kill normal cells at some strengths.
| Study | Result | People | Product |
|---|---|---|---|
| 2 | Viability fell with higher concentration in both normal and cancer cells; PARP cleavage showed apoptosis in both. |
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 6
- Do not swallow manuka oil, and keep it away from children and pets.. No poisoning report for manuka oil itself was found. The closest evidence is for tea tree oil, a different plant: a 4-year-old who swallowed a small amount became unsteady within 30 minutes and then unresponsive and needed a breathing tube, recovering over 10 hours. Manuka oil is not shown to be safer, and no one has tested how toxic it is: a 2000 paper said only tea tree oil had been tested for toxicity, and a 2020 review says clinical safety evidence is still needed. No safe amount is known and this page gives none. Case report related oil 10 8 9
- Skin allergy is a real risk with essential oils; manuka oil has not been patch-tested in the studies we read.. Tea tree oil has caused more published allergic reactions than any other essential oil, mostly from pure oil, and oxidation raises the risk. In a large clinic study of 62,354 patients, tea tree oil was the essential oil most often behind positive tests that fragrance markers missed. In 42 patients allergic to their own oils, 8 needed hospital care and 40% had not mentioned the oil. We found no patch-test data for manuka oil, so its allergy rate is unknown. In the eczema trial of a 2% manuka-oil cream, no serious adverse events were reported. Related oil reviews and clinic data 18 16 1 14
- Dish tests show the oil can harm human and animal cells at higher strengths.. In a lab study, manuka oil caused programmed cell death in normal fibroblasts as well as fibrosarcoma cells, with more effect at higher concentrations. In another, at the strength that stops a gum-disease bacterium, mouse cell viability fell to 68.81%. A third found no significant DNA damage in human skin cells after 24 hours at a very low concentration. These are dish results and do not predict harm from normal use, but they are another reason not to swallow the oil or use it strong. Laboratory 2 17 3
- Pets: tea tree oil poisoned dogs and cats; no manuka data.. A poison-centre review of 443 dogs and cats exposed to 100% tea tree oil, mostly on skin, found drooling, drowsiness, weakness, unsteady walking and tremors within 2 to 12 hours, lasting up to 72 hours; younger, smaller cats were most at risk. We found no manuka oil source for pets. A manuka-oil ear study in dog bacteria in dishes called for safety tests before any use in ears. Related oil case series 7 15
- Pregnancy, breastfeeding and children: no manuka oil source found.. In animal tissue, manuka and related oils lowered the force of rat womb contractions, and the authors suggested caution in childbirth. A review of tea tree and lavender oils and early breast development in children found four papers with eleven cases, poor reporting and no evidence supporting a link for tea tree oil; manuka was not studied. Not described does not mean safe. Ask a midwife, doctor or pharmacist. Animal tissue and gap 8 5
- Quality varies: oil makeup depends on where the plant grew.. A survey of 261 manuka plants from 87 New Zealand sites found a high-triketone type on the East Cape and ten other chemotypes elsewhere, including types rich in pinene, geranyl acetate or linalol. A 2000 paper noted that manuka samples varied more than tea tree samples. A bottle labelled manuka may therefore differ in makeup and strength. No study of adulteration of manuka oil was found. Chemical survey 4 8 9
Side effects 5
| Effect | How often | Severity and recovery | Evidence |
|---|---|---|---|
| Skin irritation or allergic contact dermatitis Related oil, not manuka oil: tea tree oil data are shown because no manuka patch-test series was found. | No rate for manuka oil found. Tea tree oil: 0.1% to 3.5% positive patch tests in routine testing (review); 0.3% in one large North American series. | Strong in about half of tea-tree-oil reactions in one series; 8 of 42 own-oil allergy patients needed hospital care Not stated in the abstracts | Related oil reviews 18 16 1 |
| Swallowing: drowsiness, unsteadiness, unconsciousness Related oil, not manuka oil: tea tree oil. | One child case with tea tree oil; no manuka case found. | Breathing tube needed in the tea-tree-oil case Recovered over 10 hours | Case report related oil 10 |
| Mild adverse events with a 2% manuka-oil cream Single product and trial; the abstract does not list mild effects. | No serious adverse events reported in 118 adults over six weeks | Not detailed in the abstract Not stated | Randomized trial 14 |
| Cell damage in dishes Dish results; not a measure of harm in people. | Dose-dependent killing of fibroblasts and fibrosarcoma cells; mouse cell viability 68.81% at the MIC in one study | n/a n/a | Laboratory 2 17 |
| Pet poisoning Related oil, not manuka oil: tea tree oil. | 443 dog and cat cases with 100% tea tree oil; none with manuka found | CNS depression, weakness, tremors; lasting up to 72 hours Not stated | Related oil case series 7 |
Liver
No liver injury linked to manuka essential oil was described in the sources we read. LiverTox was not checked for this oil. 9
How often. Not established.
Monitoring. Not applicable.
This is a safety connection. It is not evidence that Manuka Oil supports liver health.
Medicines and supplements 4
| With | Why it matters | Importance | Evidence | What to do |
|---|---|---|---|---|
| Tea tree oil, turpentine, fragrance mixes and other essential oils allergy | Cross-reaction in patch tests (shown for tea tree oil) | For tea tree oil, co-reactivity to turpentine oil is frequent, with over-representation of reactions to fragrance mix I, balsam of Peru, colophony and other essential oils. Whether manuka oil cross-reacts was not studied. | Review Low certainty 18 | If you have reacted to tea tree oil, a perfume or an essential oil, tell a pharmacist or dermatologist before trying manuka oil. |
| Medicines of any kind drug | None studied | No drug-interaction study of manuka oil was found. | Gap Not enough evidence | Ask a pharmacist, especially if you take prescription medicines. |
| Other essential oils or herbs herb-supplement | None studied | No study of manuka oil combined with other oils was found; kunzea and tea tree oils are different plants. | Gap Not enough evidence | Do not assume effects carry over from other oils. |
| Eczema creams and other skin treatments medicine-for-skin | None studied | In the trial, both groups improved the same and the plain cream matched the oil cream; no trial compared the oil with a standard eczema treatment. | Randomized trial Low certainty 14 | Do not stop prescribed eczema treatment; ask a doctor. |
Who should check first 4
| Situation | Advice | Evidence |
|---|---|---|
| Known allergy to tea tree oil, other essential oils, turpentine or fragrances | Avoid unless a doctor advises otherwise; cross-reactions are common with tea tree oil. | Review 18 1 |
| Pregnancy, labour or breastfeeding | Safety is not established; a tissue study suggested caution in childbirth. | Animal tissue 8 |
| Babies, young children and pets | Keep the oil out of reach. Related tea tree oil has poisoned children and animals. | Related oil case reports 10 7 |
| Broken, inflamed or very sensitive skin | Not studied for manuka oil; ask a doctor or pharmacist. | Gap |
Overdose, product quality and regulators
Summary. The toxicity of manuka oil has not been well tested: a 2000 paper said only tea tree oil had been tested, and a 2020 review calls for clinical safety evidence.
Amounts. No safe amount is established, and this page gives none.
Onset and course. For tea tree oil in a child, signs began within 30 minutes. In pets, within 2 to 12 hours.
Repeated use. Repeated skin exposure to related oils is the route linked to allergy; for manuka oil, not studied.
Animal data. Rat uterus and guinea-pig tissue studies (2000); cell-culture studies showing cell death at higher strengths.
Toxic parts. Which compounds cause harm in manuka oil was not stated in the abstracts read. The oil contains beta-triketones, which kill mites and block a mite enzyme in a dish.
Not read. Full text of the papers, IFRA standards, EU cosmetic safety opinions, veterinary toxicology texts, LiverTox, LactMed.
Manuka oil makeup varies by region, so strength differs from bottle to bottle.
Regional chemotypes. In 261 plants from 87 New Zealand sites, a high-triketone type (more than 20% triketones) was localised on the East Cape; ten other chemotypes had other lead compounds, including alpha-pinene, geranyl acetate and linalol. 4
Batch variation. Manuka samples varied more in antimicrobial activity than tea tree samples (2000). The 2020 review calls for standardization. 8 9
Not manuka honey. Manuka honey is made from the nectar of Leptospermum flowers; oil is from leaves. The two products are different and research on one does not carry over. 6
Adulteration. No study of adulteration or heavy-metal contamination of manuka oil was found.
| Body | Action | Date |
|---|---|---|
| New Zealand Standing Committee on Therapeutic Trials (SCOTT) (New Zealand) | The eczema trial reports SCOTT approval as required for clinical trials of a new medicine under New Zealand law (as stated in the paper's declarations). source | 2021-09-20 |
When to get medical help
- If anyone, especially a child or pet, may have swallowed manuka oil, call poison control (US: 1-800-222-1222) or your emergency number at once; do not wait for signs.
- Seek care for hives, swelling of the face or trouble breathing after any contact.
- Stop use and wash the skin if a rash, burning or blistering appears; see a doctor if it does not settle.
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
Is manuka oil safe to swallow?
No. No safe amount is known and its toxicity has not been properly tested. A child who swallowed tea tree oil, a different plant's oil, became unresponsive within an hour and needed a breathing tube. If anyone, especially a child or pet, may have swallowed it, call poison control (US: 1-800-222-1222) or your emergency number.
Can manuka oil cause an allergic reaction?
Does manuka oil help eczema?
Not shown. In 118 adults, a cream with 2% of a manuka-oil-based product did no better than plain cream over six weeks; both groups improved by the same amount. The work was linked to the product's maker. Ask your doctor about eczema care.
Does manuka oil kill germs?
Can manuka oil treat scabies?
Not shown. A dish study found it killed scabies mites and eggs, but it was not tested on skin or in people. See a doctor for scabies.
Does manuka oil fight cancer?
No. In a dish it killed fibrosarcoma cells, but it also killed normal fibroblasts. It is not a cancer treatment.
Is manuka oil the same as tea tree oil?
Is manuka oil the same as manuka honey?
No. Manuka honey is made by bees from Leptospermum nectar. The oil is distilled from leaves. Research on one does not carry over to the other.
Is manuka oil safe in pregnancy or breastfeeding?
Unknown. We found no source on manuka oil in pregnancy or breastfeeding, and in rat womb tissue it lowered contractions, so the authors urged caution in childbirth. Ask a midwife or doctor.
Is manuka oil safe for children?
Is manuka oil safe for cats and dogs?
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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 read the abstracts of 18 PubMed records, checked plant names in GBIF and compounds in PubChem. Tea tree oil data are labelled as a related oil. We did not read a LiverTox, LactMed, IFRA or FDA statement.
- 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. Industry links are labelled where the abstract gave them.
Sources 20
Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.
- Barbaud A, et al. Allergic contact dermatitis from essential oil in consumer products: Mode of uses and value of patch tests with an essential oil series. Results of a French study of the DAG (Dermato-Allergology group of the French Society of Dermatology).. Contact Dermatitis. 2023. PMID 37403438. DOI 10.1111/cod.14377. (abstract)
- Bass NI, et al. Manuka Essential Oil Triggers Apoptosis and Activation of c-Jun N-Terminal Kinase in Fibroblasts and Fibrosarcoma Cells.. Molecules. 2024. PMID 39519810. DOI 10.3390/molecules29215168. (abstract)
- Bučková M, et al. Leptospermum scoparium Essential Oil: Antibacterial Properties, Cyto/Genotoxic Effects, Antioxidant Activity, and Wound-Healing Potential In Vitro.. Molecules. 2026. PMID 42796590. DOI 10.3390/molecules31183304. (abstract)
- Douglas MH, et al. Essential oils from New Zealand manuka: triketone and other chemotypes of Leptospermum scoparium.. Phytochemistry. 2004. PMID 15184010. DOI 10.1016/j.phytochem.2004.03.019. (abstract)
- Hawkins J, et al. The relationship between lavender and tea tree essential oils and pediatric endocrine disorders: A systematic review of the literature.. Complement Ther Med. 2020. PMID 32147050. DOI 10.1016/j.ctim.2019.102288. (abstract)
- Hoang PL, et al. A Comprehensive Review of the Botany, Bioactive Compounds and Health Benefits of Leptospermum.. Chem Biodivers. 2025. PMID 39599991. DOI 10.1002/cbdv.202401335. (abstract)
- Khan SA, et al. Concentrated tea tree oil toxicosis in dogs and cats: 443 cases (2002-2012).. J Am Vet Med Assoc. 2014. PMID 24344857. DOI 10.2460/javma.244.1.95. (abstract)
- Lis-Balchin M, et al. Pharmacological and antimicrobial studies on different tea-tree oils (Melaleuca alternifolia, Leptospermum scoparium or Manuka and Kunzea ericoides or Kanuka), originating in Australia and New Zealand.. Phytother Res. 2000. PMID 11114000. DOI 10.1002/1099-1573(200012)14:8<623::aid-ptr763>3.0.co;2-z. (abstract)
- Mathew C, et al. Mānuka Oil-A Review of Antimicrobial and Other Medicinal Properties.. Pharmaceuticals (Basel). 2020. PMID 33114724. DOI 10.3390/ph13110343. (abstract)
- Morris MC, et al. Ingestion of tea tree oil (Melaleuca oil) by a 4-year-old boy.. Pediatr Emerg Care. 2003. PMID 12813303. DOI 10.1097/01.pec.0000081241.98249.7b. (abstract)
- Nammunige NA, et al. β-Triketones from Leptospermum scoparium (mānuka) oil show potential as scabicides.. Phytomedicine. 2025. PMID 39752786. DOI 10.1016/j.phymed.2024.156321. (abstract)
- Nammunige NA, et al. Corrigendum to "β-Triketones from Leptospermum scoparium (mānuka) oil show potential as scabicides" [Phytomedicine Volume 136, January 2025, 156321].. Phytomedicine. 2026. PMID 41832089. DOI 10.1016/j.phymed.2025.157725. (abstract)
- Pedonese F, et al. Antimicrobial and anti-biofilm activity of manuka essential oil against Listeria monocytogenes and Staphylococcus aureus of food origin.. Ital J Food Saf. 2022. PMID 35284338. DOI 10.4081/ijfs.2022.10039. (abstract)
- Shortt G, et al. Randomised controlled trial of mānuka oil-based ECMT-154™ vs. vehicle control for the topical treatment of eczema, conducted in community pharmacies in New Zealand.. BMC Complement Med Ther. 2026. PMID 41629897. DOI 10.1186/s12906-026-05274-w. (abstract)
- Song SY, et al. In vitro antibacterial activity of the manuka essential oil from Leptospermum scoparium combined with Tris-EDTA against Gram-negative bacterial isolates from dogs with otitis externa.. Vet Dermatol. 2020. PMID 31729809. DOI 10.1111/vde.12807. (abstract)
- Warshaw EM, et al. Positive Patch-Test Reactions to Essential Oils in Consecutive Patients From North America and Central Europe.. Dermatitis. 2017. PMID 28614106. DOI 10.1097/DER.0000000000000293. (abstract)
- Yuan Y, et al. Investigation of differential Multi-Mode antibacterial mechanisms of essential oils of Satureja montana L. and Leptospermum scoparium J.R.Forst. & G.Forst. Against Porphyromonas gingivalis.. BMC Complement Med Ther. 2025. PMID 40696347. DOI 10.1186/s12906-025-05007-5. (abstract)
- de Groot AC, et al. Tea tree oil: contact allergy and chemical composition.. Contact Dermatitis. 2016. PMID 27173437. DOI 10.1111/cod.12591. (abstract)
- n/a. GBIF Backbone Taxonomy: Leptospermum scoparium Forst. (match API read 2026-10-25). n/a. 2026. (full-text)
- n/a. PubChem: leptospermone (CID 3083632), isoleptospermone (CID 59518515), flavesone (CID 15800949), beta-caryophyllene (CID 5281515) (read 2026-10-25). n/a. 2026. (full-text)