Essential Oils & Aromatherapy · Essential oil
Anise and Star Anise Oil
Pimpinella anisum L. and Illicium verum Hook.f. · also called Aniseed oil, anise essential oil, star anise oil, Chinese star anise oil
Anise oil and star anise oil are two different licorice-smelling oils, from two unrelated plants, that both get their scent from anethole. They are used in aromatherapy and flavourings. The best human research is two small trials of coated anise oil capsules for irritable bowel syndrome, and the certainty is low. The main cautions: do not swallow either oil, EU regulators ask that children, pregnancy and breastfeeding have as little estragole as possible, and star anise tea has poisoned babies, partly because the spice can be mixed with a toxic look-alike.
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 Anise and Star Anise Oil
Anise oil comes from aniseed and star anise oil from star anise: different plants that both smell of licorice. They are used in aromatherapy and flavourings. Two small trials of coated anise oil capsules looked at IBS, but the certainty is low, and no human trial of star anise oil was found. Safety comes first: do not swallow either oil, never use them undiluted, keep them from babies, children and pets, avoid them in pregnancy and breastfeeding, and do not give babies star anise tea.
What anise and star anise oil are
Anise oil is the essential oil from the dry fruit (aniseed) of Pimpinella anisum L., in the carrot family, Apiaceae. Star anise oil is from Illicium verum Hook.fil., in the family Schisandraceae. GBIF lists both as accepted names. The two plants are unrelated.
Both oils are rich in anethole, which gives the licorice smell: 94.01% and 95.2% in two analyses of anise oil, and 83.68% in one star anise oil made from aerial parts. Estragole is a related compound found in smaller amounts.
Poison Control says it can be hard to know the species, strength or contaminants in an essential oil bottle.
What people use it for, and how strong the evidence is
For IBS there are two small trials of coated anise oil capsules from one group in Iran; the first reported 75% symptom-free against 35% on placebo. A second trial reports a better depression score in people with IBS but gives no numbers. For head lice there is one old open study of a three-oil blend. Wound healing has only been tried on cells. We found no human trial of star anise oil.
The product in each trial is not advice. This page does not tell you how much to use or how to use it. A pharmacist or aromatherapist trained in safety can advise on made products.
The research in one view
Most of the human research is small, old or from a single group. The IBS and depression trials share authors, and their abstracts give no capsule strength or funding. The lice study mixed three oils and its numbers do not add up. Lab work on bacteria, yeasts, insects and cells is common but says little about people. Authors of the IBS trial ask for more studies.
Bottled oil, capsules, blends and teas are different things
The coated capsules in the IBS trials, the three-oil lice blend, bottled anise oil, bottled star anise oil, aniseed tea and star anise tea are different products from two different plants. Results for one do not show that another works or is safe. Poison Control says diluting an essential oil in a carrier oil is the best way to avoid a bad skin reaction, and that oils should not go on damaged skin.
What authorities say
The EU herbal committee (HMPC) lists aniseed fruit tea for mild spasm-type gut complaints and cough with a cold, not established under 12 years, not recommended in pregnancy or breastfeeding, and not for more than two weeks (monograph adopted 2013). Its estragole statement, a draft revision dated 2014, asks for minimal exposure of children and pregnant or breastfeeding women. EFSA's feed panel declined to assess an estragole-rich star anise fraction in 2023. Poison Control and Pet Poison Helpline give the general and pet warnings. We did not find or read a statement from the FDA, NCCIH, LiverTox or LactMed.
Pets
Pet Poison Helpline says cats and birds are at the greatest risk from essential oils, and that swallowing is the highest-risk route. Anise and star anise are not on its list of common poisoning oils, but that is not proof they are safe, and we found no anise-specific pet report. Keep the oils away from pets and call a vet or pet poison line after any exposure.
At a glance
Traditional uses history, not proof
- Aniseed as a tea is a traditional European remedy for mild spasm-type gut complaints with bloating and wind, and for cough with a cold (EU herbal committee; this is the fruit tea, not the oil).
- Anise oil has been suggested for bowel disorders in Traditional Persian Medicine texts (trial authors).
- Star anise is used in traditional medicine and as a spice; in some cultures star anise tea has been given to infants for colic, which has caused poisonings.
Studied for research
- Irritable bowel syndrome, enteric-coated anise oil capsules, low
- Mild to moderate depression in people with IBS, anise oil, very-low
- Head lice, a three-oil blend including anise oil, very-low
- Wound healing, anise oil on lab-grown cells only, insufficient
Main compounds
- trans-Anethole, 94.01% and 95.2% in two anise oil analyses; 83.68% in one star anise oil
- Estragole, 1 to 5% of anise oil (EMA table); up to 25% in an enriched star anise feed fraction (EFSA)
- Anisatin, the toxin of Japanese star anise (Illicium anisatum), a look-alike found mixed into star anise
Common forms
- Anise essential oil from the fruit of Pimpinella anisum
- Star anise essential oil from Illicium verum
- Enteric-coated capsules of anise oil (used in IBS trials)
- Aniseed tea and star anise tea are different products
Research links: EMA: EU herbal monograph on aniseed fruit · EMA: Public statement on estragole · Poison Control: Essential oils · Pet Poison Helpline: Essential oils · Infants poisoned by star anise tea, US report (abstract) · Anise oil capsules for IBS, trial (abstract) · Research Library · Genes & Biomarkers Library
What it is and its history
- Accepted scientific name
- Pimpinella anisum and Illicium verum (two plants, two oils)
- Naming authority
- Pimpinella anisum L.; Illicium verum Hook.fil.
- Common names
- Anise oil (English); Aniseed oil (English); Star anise oil (English); Chinese star anise oil (English)
- Family or group
- Anise is in the carrot family, Apiaceae. Star anise is in Schisandraceae per GBIF (older papers write Magnoliaceae). They are unrelated plants that share a licorice-like smell.
- Classification
- Plantae > Tracheophyta > Magnoliopsida > Apiales (anise); Austrobaileyales (star anise) > Apiaceae (anise); Schisandraceae (star anise) > Pimpinella; Illicium > Pimpinella anisum; Illicium verum
- Native range
- Not covered by the sources read.
- Habitat
- Not checked.
- What it looks like
- Part used: Anise oil comes from the dry fruit (aniseed). Star anise oil comes from the fruit of Illicium verum; one lab study distilled aerial parts. This page does not describe how to recognise the fruits.
- Cultivation
- Not covered by the sources read.
- Harvest and processing
- The star anise oil analysed in a 2023 lab study was made by hydrodistillation of aerial parts. Other methods and the anise oil methods were not read.
- Look-alikes and adulterants
- Name: Japanese star anise (Illicium anisatum); Note: A toxic species. Case reports from the US and Switzerland say Chinese star anise has been found mixed with it, that the fruits look alike and are often sold broken or ground, and that chemical analysis is usually needed to detect it. This page gives no way to tell them apart.
- Sustainability and conservation
- Not checked.
Traditional use and history history, not clinical proof
| Tradition or era | Documented use | Source |
|---|---|---|
| Traditional European herbal medicine (fruit as a tea) | The EU herbal committee lists aniseed as a traditional herbal medicinal product for mild spasm-type gut complaints with bloating and wind, and as an expectorant in cough with a cold, based on long-standing use. This concerns the fruit as a tea, not the oil. | EMA, HMPC |
| Traditional Persian medicine | The authors of the IBS trial say anise is well recognised in Traditional Persian Medicine texts and that anise oil has been suggested there for bowel disorders. | Mosaffa-Jahromi 2016 |
| Traditional use of star anise, including for infant colic | A 2023 review says star anise is used in traditional medicine to warm Yang, disperse cold, regulate Qi and relieve pain, and as a condiment. Case reports say star anise tea is given to infants for colic in several cultures, which has led to poisonings. | Zou 2023; Ize-Ludlow 2004; Perret 2011 |
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 |
|---|---|---|---|---|
| trans-Anethole PubChem 637563 | phenylpropanoid | Anise and star anise fruit oils 94.01% and 95.2% in two analyses of anise oil; 83.68% as (E)-anethole in one star anise oil made from aerial parts. | Allergen in case reports. In lab tests it forms the same kinds of reactive breakdown products as estragole, at lower levels; the EU aniseed monograph says it is unlikely to be genotoxic in the body. Its role in the oils' effects in people is not shown. 18 5 13 16 2 21 28 | Human lab |
| Estragole PubChem 8815 | phenylpropanoid (alkenylbenzene) | Anise and star anise fruit and oil (minor) 1 to 5% of anise oil (EMA table). A star anise terpene feed fraction is specified at up to 25% (EFSA). | Genotoxic carcinogen in rodents (EU statement); the reason for EU limits on exposure of young children and in pregnancy. 22 7 28 | Regulatory and animal |
| Anisatin | neurotoxic sesquiterpene lactone | Japanese star anise (Illicium anisatum) fruit 7800 micrograms per kg in a contaminated star anise sample (Swiss case); the Swiss maximum tolerance value is 1000. | The French case report says it acts as a non-competitive antagonist of GABA receptors. It is the toxin behind the infant poisonings. 15 | Human case report |
| Limonene and alpha-pinene (minor) | terpenes | Star anise oil 3.19% and 0.71% in one star anise oil analysis. | Not studied for effect here. 13 | Laboratory |
Mechanisms, receptors and pathways
| Target or pathway | Gene or receptor | What was found | Level |
|---|---|---|---|
| Estragole and anethole bioactivation | CYP enzymes and sulfotransferases | Estragole is hydroxylated and then sulfated to a reactive form that binds DNA and proteins; anethole forms the same kinds of adducts at lower levels. In volunteers drinking fennel tea for four weeks a blood marker rose and then fell after washout. This shows exposure, not harm, and it was fennel tea, not anise oil. 2 9 22 | Human pilot and lab |
| Anisatin toxicity | GABA receptors | Anisatin from Japanese star anise is described as a non-competitive GABA receptor antagonist, which fits seizure-like events. 15 | Case report background |
| Anti-microbial and insect-killing activity | Not tested | In the lab, star anise oil acted against eight food bacteria, anise oil slowed Candida yeasts and killed stored-product beetles, and a 1:1 anise and fennel oil mixture killed housefly eggs. These are lab and insect findings and say nothing about people. 13 18 5 14 | Laboratory |
| Wound-healing cells | Not tested | Anise oil increased the growth of mouse fibroblast cells in a dish. 17 | Laboratory |
Absorption, metabolism and elimination
- Absorption
- Skin absorption of estragole is unknown (EU statement). Absorption of anise oil in people was not found in the sources read.
- Distribution
- Not established in the sources read.
- Metabolism
- In 12 volunteers drinking fennel tea, a breakdown product of estragole and anethole appeared in urine, mostly in the first hour, with a half-life of about 1.1 hours and nearly complete clearance within 8 hours. In the Swiss infant, anisatin was found in urine at 22 hours and not at 33 hours.
- Elimination
- See metabolism.
- Bioavailability
- Not established.
Isolated compounds versus whole extracts
Bottled anise oil, bottled star anise oil, coated anise oil capsules, a three-oil lice blend, aniseed tea and star anise tea are different products from two different plants. Results do not carry between them. The EU monograph limits are for aniseed as a tea. The coated capsule trials do not show that bottled oil works or is safe, and the star anise tea poisonings are about tea and possible contamination, not the oil.
Nutritional composition
Anise and star anise oils are not foods or nutrients and are not supplements to swallow. Aniseed and star anise as spices are covered on their own pages.
1 low certainty2 very low certainty1 not enough evidence
What is Anise and Star Anise Oil good for?
The uses people ask about and how strong the evidence is for each. Read the certainty label first: the human results are for coated anise oil capsules or a mixed blend, not bottled oil, and none is advice to swallow or use the oil undiluted. We found no human trial of star anise oil.
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.
Irritable bowel syndrome symptoms (enteric-coated anise oil capsules)
Low certaintyOne 2016 trial of 120 people in Iran found that coated anise oil capsules left more people free of IBS symptoms than placebo and than a peppermint oil medicine. It is a single trial of a medicine-type capsule, not bottled oil, and it is not a reason to swallow aromatherapy oil.
3 studiesStudied as set capsules, set blends or lab samples (details are in th…
Studies, doses and limits
What the trials found
A 2016 three-arm, double-blind, randomised trial of 120 people with IBS in Iran: anise oil capsules (coated so they open in the gut, called AnisEncap), placebo, and Colpermin, a coated peppermint oil medicine. Capsules were taken for 4 weeks with 2 weeks of follow-up. Primary outcome: a symptom score on a visual scale.
Results
By intention-to-treat, 75% of the anise oil group, 35% of the placebo group and 52.5% of the peppermint group were free from IBS symptoms (P<0.001). Anise oil beat both on pain, bloating, diarrhoea, constipation, reflux, headache, tiredness, satisfaction and quality of life at 4 weeks and 2 weeks later (P<0.0001). Number needed to treat 4. The abstract does not report side effects.
Effect sizes as reported
Symptom-free after 4 weeks (intention-to-treat): 75% on anise oil capsules vs 35% on placebo vs 52.5% on a peppermint oil medicine; number needed to treat 4.
Why this rating
One trial from one group, 120 people, 4 weeks. The abstract gives no capsule strength, funding or trial registration. The result is unusually large (75% symptom-free against 35% on placebo), and a single trial of this kind needs repeating by others before it can be trusted. A coated capsule medicine also behaves differently from bottled oil.
Form and dose studied
Studied as set capsules, set blends or lab samples (details are in the results). No amounts are advised here. Bottled essential oil is very concentrated: do not swallow it and do not use it undiluted; ask a pharmacist.
Who was studied
Adults with IBS in Iran.
Limits
Capsule strength, contents and funding are not in the abstract. No independent repeat found. The 2-week follow-up is short. Not about aromatherapy oil, star anise oil or use on the skin.
Why researchers looked
The authors say anise oil is described for bowel disorders in Traditional Persian Medicine texts.
Traditional use
The IBS trial authors say anise oil has been suggested for bowel disorders in Persian medical textbooks. The EU herbal committee lists aniseed as a traditional tea for mild spasm-type gut complaints with bloating and wind (the fruit as a tea, not the oil).
Proposed mechanism Preliminary mechanism
The authors say the way it might work is not known and suggest more studies on this.
A proposed mechanism does not show that the effect happens in people.
Anise oil is mostly anethole, and the EU committee asks that young children, pregnancy and breastfeeding have as little estragole as possible. Do not swallow bottled essential oil (see Safety). A pharmacist or doctor should advise on any product made for the gut.
Mild to moderate depression in people with IBS (anise oil)
Very low certaintyA second trial from the same group in Iran, of 120 people with IBS and mild to moderate depression, reports that anise oil scored better than a peppermint medicine and placebo on a depression questionnaire. The abstract gives no numbers, so we cannot say how big the change was.
2 studiesStudied as set capsules, set blends or lab samples (details are in th…
Studies, doses and limits
What the trials found
A 2017 randomised, double-blind trial of 120 people with IBS and mild to moderate depression (Beck Depression Inventory-II), given anise oil, Colpermin or placebo for 4 weeks, with follow-up at week 6.
Results
At week 4 and week 6 the authors report that anise oil was significantly better than both the active medicine and placebo. No scores, differences or confidence intervals are in the abstract.
Effect sizes as reported
No scores are given in the abstract.
Why this rating
One trial with no numbers in the abstract, from the same group and with the same design as the IBS trial; we cannot tell whether it used the same people. Depression scores are self-rated and a smell or taste can reveal the treatment.
Form and dose studied
Studied as set capsules, set blends or lab samples (details are in the results). No amounts are advised here. Bottled essential oil is very concentrated: do not swallow it and do not use it undiluted; ask a pharmacist.
Who was studied
Adults with IBS and mild to moderate depression.
Limits
No numbers, strength, funding or registration in the abstract. Possible overlap with the IBS trial. Not a test of aromatherapy, and not advice for depression: anyone with low mood should talk to a doctor.
Why researchers looked
Low mood is common in people with IBS, and the group tested their anise oil product on it.
Traditional use
Not described in the source read for this use.
Proposed mechanism Preliminary mechanism
The authors say the mechanism is unknown.
A proposed mechanism does not show that the effect happens in people.
A low mood that does not lift, or any thoughts of self-harm, need urgent medical help, not an essential oil. See the Safety tab for swallowing, children, pregnancy and allergy.
Head lice (a three-oil blend with anise oil, coconut oil and ylang ylang oil)
Very low certaintyA 2002 open study in Jerusalem schoolchildren found a blend of coconut, anise and ylang ylang oils cleared head lice about as often as a pesticide spray. The blend cannot be credited to anise oil alone, and the study was not blinded.
3 studiesStudied as set capsules, set blends or lab samples (details are in th…
Studies, doses and limits
What the trials found
A 2002 randomised, open (unblinded) study of schoolchildren aged 6 to 14 in six Jerusalem schools who had head lice. The blend was applied to hair three times, 5 days apart; the comparison was a pesticide spray (permethrin, malathion and piperonyl butoxide).
Results
Treatment succeeded in 60 children (92.3%) with the blend and 59 children (92.2%) with the spray. No significant side effects were reported with either. The counts and percentages do not fit the stated 119 children, so the numbers are uncertain.
Effect sizes as reported
Success 92.3% (natural blend) vs 92.2% (pesticide spray).
Why this rating
An old, open study of a mixed product, with numbers in the abstract that do not add up, and no blinding. The effect cannot be assigned to anise oil.
Form and dose studied
Studied as set capsules, set blends or lab samples (details are in the results). No amounts are advised here. Bottled essential oil is very concentrated: do not swallow it and do not use it undiluted; ask a pharmacist.
Who was studied
Schoolchildren aged 6 to 14 in Jerusalem.
Limits
Three oils in one product. Open design. Inconsistent numbers. Strength, funding and long-term follow-up are not in the abstract. Poison Control warns that children have thin skin and immature livers, and EU regulators ask for minimal estragole exposure in young children, so this is not a reason to put anise oil on a child's hair.
Why researchers looked
The authors say common lice treatments are often ineffective and wanted a natural option.
Traditional use
Not described in the sources read for this use.
Proposed mechanism Preliminary mechanism
No mechanism was tested in the abstract.
A proposed mechanism does not show that the effect happens in people.
Ask a pharmacist or doctor about head-lice treatment for a child. Keep essential oils away from young children (see Safety).
Wound healing (anise oil on lab-grown mouse cells)
Not enough evidenceIn a 2023 lab study anise oil was not toxic to mouse skin-type cells and made them grow faster. Nobody has tested it on a wound, and cells in a dish do not show that it helps or is safe on skin.
2 studiesLab work only: no use is advised.
Studies, doses and limits
What the trials found
None. A 2023 cell study on mouse fibroblast cells treated for 24 to 72 hours.
Results
Anise oil was not toxic to the cells and increased their growth at the concentrations tested. The authors say it could be used on wounds only if clinical trials confirm the data.
Effect sizes as reported
None in people.
Why this rating
Lab cells only. No animal or human wound was treated. Anise oil can cause skin allergy in some people (see Safety), which cell tests cannot show.
Form and dose studied
Lab work only: no use is advised.
Who was studied
None (mouse cells).
Limits
Cells in a dish; no animal or human data; the abstract gives no funding.
Why researchers looked
The authors wanted to see whether anise oil could be a topical wound healer.
Traditional use
Not described in the sources read for this use.
Proposed mechanism Preliminary mechanism
Cells in a dish were treated and then counted and photographed. No mechanism in the body was tested.
A proposed mechanism does not show that the effect happens in people.
Do not put the oil on wounds. Poison Control says not to use essential oils on damaged skin.
Connections to the rest of health
How Anise and Star Anise 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 |
|---|---|---|---|---|
| Digestive Support | Low certainty | Irritable bowel syndrome symptoms (enteric-coated anise oil capsules): One 2016 trial of 120 people in Iran found that coated anise oil capsules left more people free of IBS symptoms than placebo and than a peppermint oil medicine. It is a single trial of a medicine-type capsule, not bottled oil, and it is not a reason to swallow aromatherapy oil. | 10 21 22 | |
| Mood Balance | Very low certainty | Mild to moderate depression in people with IBS (anise oil): A second trial from the same group in Iran, of 120 people with IBS and mild to moderate depression, reports that anise oil scored better than a peppermint medicine and placebo on a depression questionnaire. The abstract gives no numbers, so we cannot say how big the change was. | 11 10 | |
| Healthy Skin | Very low certainty | Head lice (a three-oil blend with anise oil, coconut oil and ylang ylang oil): A 2002 open study in Jerusalem schoolchildren found a blend of coconut, anise and ylang ylang oils cleared head lice about as often as a pesticide spray. The blend cannot be credited to anise oil alone, and the study was not blinded. | 12 26 22 | |
| Healthy Skin | Not enough evidence | Wound healing (anise oil on lab-grown mouse cells): In a 2023 lab study anise oil was not toxic to mouse skin-type cells and made them grow faster. Nobody has tested it on a wound, and cells in a dish do not show that it helps or is safe on skin. | 17 26 |
B. Body systems
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Digestive System | Biological association | Low certainty | Studied for: Irritable bowel syndrome symptoms (enteric-coated anise oil capsules) | 10 21 22 |
| Nervous System | Biological association | Very low certainty | Studied for: Mild to moderate depression in people with IBS (anise oil) | 11 10 |
| Integumentary System | Biological association | Very low certainty | Studied for: Head lice (a three-oil blend with anise oil, coconut oil and ylang ylang oil) Studied for: Wound healing (anise oil on lab-grown mouse cells) | 12 26 22 17 |
E. Health conditions
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Contact dermatitis | Adverse effect or risk | Documented risk | Allergy is listed in the EU monograph; anethole contact allergy case report. Allergy is listed in the EU monograph. Preparation or compound: Aniseed and anethole |
21 16 |
| Infant star anise tea poisoning | Adverse effect or risk | Case report | US and Swiss case reports; the tea, not the oil. Preparation or compound: Star anise tea (contaminated with Japanese star anise) |
8 15 |
| Irritable bowel syndrome | Low certainty | One trial of 120 people; see Benefits. One trial of 120 people; capsule medicine, not bottled oil. Preparation or compound: Enteric-coated anise oil capsules |
10 |
I. Biomarkers
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Share of people free of IBS symptoms | Biological association | Low certainty | Measured in trials: increase. A lab change is not the same as a health benefit. | 10 |
| Depression questionnaire score (Beck Depression Inventory-II) | Biological association | Very low certainty | Measured in trials: decrease. A lab change is not the same as a health benefit. | 11 |
| Head lice cleared | Biological association | Very low certainty | Measured in trials: increase. A lab change is not the same as a health benefit. | 12 |
J. Genes, receptors and enzymes
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| CYP enzymes and sulfotransferases (estragole and anethole activation) | Preliminary mechanism | Human pilot and lab | Liver enzymes turn estragole and, less so, anethole into reactive forms (lab and human exposure work). | 2 9 |
| GABA receptors (anisatin) | Preliminary mechanism | Case report background | The toxin of Japanese star anise blocks GABA receptors (case report background statement). | 15 |
L. Active compounds
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| trans-Anethole | Biological association | Human lab | Allergen in case reports. In lab tests it forms the same kinds of reactive breakdown products as estragole, at lower levels; the EU aniseed monograph says it is unlikely to be genotoxic in the body. Its role in the oils' effects in people is not shown. Preparation or compound: Anise and star anise fruit oils |
18 5 13 16 2 21 28 |
| Estragole | Biological association | Regulatory and animal | Genotoxic carcinogen in rodents (EU statement); the reason for EU limits on exposure of young children and in pregnancy. Preparation or compound: Anise and star anise fruit and oil (minor) |
22 7 28 |
| Anisatin | Biological association | Human case report | The French case report says it acts as a non-competitive antagonist of GABA receptors. It is the toxin behind the infant poisonings. Preparation or compound: Japanese star anise (Illicium anisatum) fruit |
15 |
| Limonene and alpha-pinene (minor) | Biological association | Laboratory | Not studied for effect here. Preparation or compound: Star anise oil |
13 |
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 Anise and Star Anise 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 20 PubMed papers, the full EMA aniseed monograph and estragole statement, and the Poison Control and Pet Poison Helpline pages, and checked plant names in GBIF and compounds in PubChem. We did not read a statement from the FDA, NCCIH, LiverTox or LactMed.
Study library: every study we checked 28
| Study | Design | People | Product, dose, length | Result |
|---|---|---|---|---|
| Bahr 2019 The Effects of Various Essential Oils on Epilepsy and Acute Seizure: A Systematic Review. Evid Based Complement Alternat Med · PMID 31239862 · DOI |
Systematic review human, animal and lab (review) |
Human case studies, animal models and in vitro studies of essential oils and seizures | Essential oils n/a n/a n/a · vs n/a |
The review says some essential oils can trigger seizures in people with and without epilepsy. It names sage, hyssop, rosemary, camphor, pennyroyal, eucalyptus, cedar, thuja and fennel for internal use. Anise and star anise are not named in the abstract. Methods, limits and fundingOutcomes: Convulsant or anticonvulsant effects Limitations: We read only the abstract. Not being named is not proof of safety. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Bergau 2021 Bioactivation of estragole and anethole leads to common adducts in DNA and hemoglobin. Food Chem Toxicol · PMID 34015424 · DOI |
Laboratory and pilot human human pilot and lab |
Liver fractions from rats and humans, and a pilot with volunteers drinking fennel tea for four weeks | Estragole and anethole; fennel tea in the pilot n/a n/a Four weeks of tea in the pilot · vs None |
Estragole and anethole (found in herbs like fennel, basil and anise) both form reactive breakdown products that bind to proteins and DNA in lab tests, anethole at lower levels. In the pilot, a blood marker rose during four weeks of fennel tea and fell after stopping. The authors suggest the marker may monitor internal exposure. Methods, limits and fundingOutcomes: DNA and blood protein adducts Limitations: Lab and a small pilot. It shows exposure, not harm. It was fennel tea, not anise oil. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Berghea 2025 Spices, herbs and allergic reactions in children: myth or reality - a narrative review with scoping elements. Front Allergy · PMID 41306764 · DOI |
Narrative review human (review) |
Children, from case reports and clinical, immunologic and molecular studies | Spices and herbs as food allergens n/a n/a n/a · vs n/a |
Spice and herb allergies are increasingly recognised in children, from mild mouth reactions to anaphylaxis. The most often implicated spices include mustard, celery, coriander, fennel, cumin, anise and pepper. Cross-reactivity with birch and mugwort pollen is common. Methods, limits and fundingOutcomes: Allergic reactions to spices and herbs Limitations: A narrative review about eating spices, not about the oil on the skin. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Burkhard 1999 Plant-induced seizures: reappearance of an old problem. J Neurol · PMID 10460442 · DOI |
Case report |
3 Three healthy people (two adults, one child) with seizures after taking essential oils by mouth |
Essential oils taken by mouth for therapeutic purposes n/a n/a n/a · vs None |
A survey of the literature names the essential oils of 11 plants as powerful convulsants (eucalyptus, fennel, hyssop, pennyroyal, rosemary, sage, savin, tansy, thuja, turpentine and wormwood). Anise and star anise are not on that list. Methods, limits and fundingOutcomes: Seizures Limitations: The abstract does not say which patient took which oil. A list that leaves anise out does not prove anise oil is safe. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Denett 2023 Chemical composition and insecticidal activity of essential oils from cultivated and native aromatic plants of Argentina against Carpophilus dimidiatus (Fabricius) (Nitidulidae) and Oryzaephilus mercator (L.) (Silvanidae). Nat Prod Res · PMID 36622895 · DOI |
Laboratory lab (insects) |
Essential oils of six aromatic plants in Argentina tested on two stored-product beetles | Anise (Pimpinella anisum) essential oil, aerial parts oil n/a n/a · vs Other oils |
trans-Anethole made up 95.2% of the anise oil analysed. The anise oil killed the beetles tested. Methods, limits and fundingOutcomes: Chemical composition; insect killing Limitations: Lab work on insects; it says nothing about people. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Dosoky 2021 Maternal Reproductive Toxicity of Some Essential Oils and Their Constituents. Int J Mol Sci · PMID 33673548 · DOI |
Narrative review human, animal and lab (review) |
Review of reproductive effects of essential oils and constituents | Essential oils and constituents including anethole n/a n/a n/a · vs n/a |
The review says using herbs, herbal preparations or essential oils in pregnancy is questionable and lists anethole among the constituents it summarises for reproductive effects. The abstract gives no conclusion about anise oil. Methods, limits and fundingOutcomes: Abortion, hormone effects, maternal toxicity, malformations, embryo-fetal toxicity Limitations: We read only the abstract. It does not say what was found for anethole or for anise or star anise oil. Funding and conflicts: Not stated in the abstract. Read: abstract |
| EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) 2023 Safety and efficacy of a feed additive consisting of a fraction of the essential oil from the fruit and leaves of Illicium verum Hook.f. (star anise terpenes) for use in all animal species (FEFANA asbl). EFSA J · PMID 37869251 · DOI |
Regulatory opinion n/a (regulatory) |
Feed additive "star anise terpenes" for animals, assessed by the European Food Safety Authority panel | A fraction of the essential oil from the fruit and leaves of Illicium verum fruit and leaf oil fraction n/a n/a · vs n/a |
The additive contains up to 25% estragole by specification and is made by a process that enriches this genotoxic carcinogen. The panel considered it inappropriate to assess the safety and efficacy of the additive. Methods, limits and fundingOutcomes: Safety and efficacy assessment for animal feed Limitations: It concerns an enriched animal-feed fraction, not bottled aromatherapy oil. The panel did not conclude on safety; it declined to assess it. Funding and conflicts: Not applicable (EFSA scientific opinion). Read: abstract |
| Ize-Ludlow 2004 Neurotoxicities in infants seen with the consumption of star anise tea. Pediatrics · PMID 15492355 · DOI |
Case series |
7 Seven infants who had neurologic reactions after star anise tea at home, in the United States |
Star anise tea (Chinese star anise, Illicium verum) fruit, as a tea Not stated in the abstract Not stated in the abstract · vs None (case report) |
The authors report 7 infants with adverse neurologic reactions after star anise tea given at home. They also found evidence that Chinese star anise has been contaminated with toxic Japanese star anise (Illicium anisatum). They say star anise tea should no longer be given to infants and call for stricter import rules. Methods, limits and fundingOutcomes: Adverse neurologic reactions Limitations: Case series: it shows reports, not how often it happens. It is about tea made from the fruit, not the essential oil. The abstract does not describe the symptoms or the tea strength. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Monien 2019 Detection of N-Acetyl-S-[3'-(4-methoxyphenyl)allyl]-l-Cys (AMPAC) in Human Urine Samples after Controlled Exposure to Fennel Tea: A New Metabolite of Estragole and trans-Anethole. Chem Res Toxicol · PMID 31565931 · DOI |
Human exposure study |
12 12 healthy volunteers who drank fennel tea |
Fennel tea (estragole and trans-anethole); one volunteer also took isolated trans-anethole fruit, as tea 500 mL of tea containing 2.2 mg estragole (trial detail, not advice) Single exposure · vs None |
The marker appeared mainly in the first hour with a half-life of about 1.1 hours and was almost cleared within 8 hours; the total excreted ranged from 93 to 1076 ng between people. It also formed, in far smaller amounts, in the volunteer who took isolated trans-anethole. Methods, limits and fundingOutcomes: Urine marker of estragole and anethole breakdown (AMPAC) Limitations: It shows exposure, not harm. It was fennel tea, not anise oil, but anethole is the main compound of anise oil. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Mosaffa-Jahromi 2016 Efficacy and safety of enteric coated capsules of anise oil to treat irritable bowel syndrome. J Ethnopharmacol · PMID 27815079 · DOI |
Randomized controlled trial |
120 120 people with irritable bowel syndrome in Iran |
Enteric-coated capsules of anise oil ("AnisEncap") oil, in coated capsules 3 capsules a day (trial detail, not advice; the strength per capsule is not in the abstract) 4 weeks, with 2 more weeks of follow-up · vs Placebo capsules, and Colpermin (an enteric-coated peppermint oil medicine) |
By intention-to-treat, 75% of the anise oil group, 35% of the placebo group and 52.5% of the peppermint group were free from IBS symptoms (P<0.001). Anise oil was better than both on the listed symptoms after 4 weeks and 2 weeks later (P<0.0001). Number needed to treat 4. The authors suggest further studies on how it works. 75% vs 35% (placebo) vs 52.5% (peppermint) symptom-free; NNT 4 Methods, limits and fundingOutcomes: Symptom score on a visual scale (primary); IBS quality of life (secondary) Limitations: One trial, from one research group in Iran. The abstract does not give the strength of the oil, what else was in the capsule, funding or a trial registration. A coated capsule medicine is not bottled aromatherapy oil. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Mosaffa-Jahromi 2017 Effectiveness of Anise Oil for Treatment of Mild to Moderate Depression in Patients With Irritable Bowel Syndrome: A Randomized Active and Placebo-Controlled Clinical Trial. J Evid Based Complementary Altern Med · PMID 26873392 · DOI |
Randomized controlled trial |
120 120 people with irritable bowel syndrome and mild to moderate depression |
Anise oil (traditional Persian medicine product) oil, product form not stated in the abstract Not stated in the abstract 4 weeks of treatment and a follow-up at week 6 · vs Colpermin (peppermint oil medicine) and placebo |
At week 4 and at week 6 the authors report a significant advantage of anise oil over both the active and placebo groups. The abstract gives no scores or confidence intervals, and says the mechanism is unknown. Methods, limits and fundingOutcomes: Depression score (Beck Depression Inventory-II) Limitations: No numbers in the abstract. Same research group and the same kind of design as the IBS trial; the abstract does not say whether the same people were enrolled, so the two should not be counted as independent. The product, strength and funding are not in the abstract. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Mumcuoglu 2002 The in vivo pediculicidal efficacy of a natural remedy. Isr Med Assoc J · PMID 12389342 |
Randomized controlled trial |
119 Schoolchildren aged 6 to 14 in Jerusalem with head lice |
A combination head-lice product containing coconut oil, anise oil and ylang ylang oil ("Chick-Chack") oil blend, on the hair Not stated in the abstract (applied for 15 minutes, three times) Three applications 5 days apart · vs A pesticide spray (permethrin, malathion and piperonyl butoxide), in an open study |
Treatment succeeded in 60 children (92.3%) with the natural product and 59 children (92.2%) with the pesticide spray. No significant side effects were reported with either. 92.3% vs 92.2% success Methods, limits and fundingOutcomes: Cure of head louse infestation; side effects Limitations: A 2002 open (unblinded) study of a three-oil blend, so the result cannot be credited to anise oil. The abstract says 119 children were randomised but the counts and percentages do not fit that total, so the numbers are uncertain. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Noumi 2023 Illicium verum L. (Star Anise) Essential Oil: GC/MS Profile, Molecular Docking Study, In Silico ADME Profiling, Quorum Sensing, and Biofilm-Inhibiting Effect on Foodborne Bacteria. Molecules · PMID 38067422 · DOI |
Laboratory lab |
Star anise essential oil from the aerial parts, tested in the lab for composition and effect on food bacteria | Star anise (Illicium verum) essential oil, hydrodistilled aerial parts n/a n/a · vs Isolated trans-anethole |
Twenty-four components made up 92.55% of the oil. (E)-anethole was 83.68%, limonene 3.19% and alpha-pinene 0.71%. The oil acted against eight bacterial strains in the lab. Methods, limits and fundingOutcomes: Chemical composition; antibacterial and antibiofilm effects Limitations: Lab work on one oil sample made from aerial parts, not necessarily the fruit oil sold as star anise oil. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Passara 2026 Anise (Pimpinella anisum) and fennel (Foeniculum vulgare) essential oils and their combination as natural and safe housefly (Musca domestica) ovicides. Front Insect Sci · PMID 42112244 · DOI |
Laboratory lab (insects) |
Housefly eggs treated with oils in the lab; earthworm safety test | Anise and fennel essential oils, singly and combined 1:1 oil n/a Up to one year of storage · vs Alpha-cypermethrin insecticide |
The 1:1 mixture killed housefly eggs completely for up to 6 months and 95% after one year; no apparent toxicity to earthworms was seen. Methods, limits and fundingOutcomes: Egg-killing activity; effect on earthworms Limitations: Insects and earthworms only. It says nothing about people. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Perret 2011 [Apparent life-threatening event in infants: think about star anise intoxication!]. Arch Pediatr · PMID 21652187 · DOI |
Case report |
1 A 2-month-old infant in Switzerland brought to an emergency unit |
Star anise infusion (Chinese star anise contaminated with Japanese star anise) fruit, as an infusion Three bottles, each of 200 mL made with 4 to 5 fruits (as the parents reported); a trial detail, not advice Hours before the symptoms · vs None (case report) |
The infant had 3 episodes of blue colour of the skin and stiffening of the limbs, irritability and arching of the body, and recovered over hours. Anisatin, the toxin of Japanese star anise, was found in urine 22 hours after the last drink (none at 33 hours). The fruit sample had 7800 micrograms per kg of anisatin; the Swiss maximum tolerance value is 1000. Methods, limits and fundingOutcomes: Seizure-like events; anisatin in urine and in the fruit sample Limitations: One case. It is about tea from the fruit, not the oil. The authors say chemical analysis is usually needed to detect the adulteration. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Poon 2006 Cheilitis caused by contact allergy to anethole in spearmint flavoured toothpaste. Australas J Dermatol · PMID 17034478 · DOI |
Case report |
1 A 63-year-old woman with 6 years of lip inflammation |
Anethole, a flavouring in her toothpaste flavouring compound n/a 6 years of symptoms · vs None |
Patch testing was positive to anethole, and her cheilitis cleared after she stopped the flavoured toothpaste. Methods, limits and fundingOutcomes: Patch test; lip inflammation Limitations: One case. It shows anethole can cause contact allergy; it is not about anise oil itself. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Sungur 2023 Efficacy and toxicity of anise oil as a potential topical wound healer: a cell culture study. Eur Rev Med Pharmacol Sci · PMID 36971216 · DOI |
Laboratory lab (cells) |
Mouse fibroblast cells grown in the lab | Anise oil oil, applied to cells 3.13 to 100 micromolar on cells 24 to 72 hours · vs Untreated cells |
Anise oil was not toxic to the cells and increased their growth at the doses tested. The authors say it could be used on wounds only if clinical trials confirm the data. Methods, limits and fundingOutcomes: Cell survival and growth Limitations: Cells in a dish only. No animal or human wound was treated. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Vieira 2019 Chemical composition of essential oils from the apiaceae family, cytotoxicity, and their antifungal activity in vitro against candida species from oral cavity. Braz J Biol · PMID 30328892 · DOI |
Laboratory lab |
Essential oils of cumin, dill, anise and fennel tested in the lab (chemical analysis, cell toxicity, anti-yeast tests) | Anise (Pimpinella anisum) essential oil oil n/a n/a · vs Other carrot-family oils |
The main compound of the anise oil was trans-anethole (94.01%). Anise oil was not toxic to the mouse cells tested at any concentration used, and it slowed Candida yeasts in the lab. Methods, limits and fundingOutcomes: Chemical composition; toxicity to mouse cells; effect on Candida yeasts Limitations: Lab work on one oil sample. It cannot be applied to people. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Wangdi 2024 Case series: star anise toxicity presenting to the emergency department in Eastern Regional Referral Hospital in Bhutan. Int J Emerg Med · PMID 39266976 · DOI |
Case series |
2 Two adults in Bhutan with stomach and nerve symptoms after eating star anise fruit |
Star anise fruit (species not confirmed in the abstract) fruit Not stated in the abstract Not stated in the abstract · vs None (case report) |
Both patients had stomach and nerve symptoms, tests for other causes were negative, they were managed with supportive care and discharged after 24 hours of observation. The authors say toxicity is reported with adulteration by toxic look-alike species and with high toxic dose. Methods, limits and fundingOutcomes: Gut and nerve symptoms; recovery Limitations: Two cases. The abstract does not say which species was eaten or whether it was tested. It is about the fruit, not the oil. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Zou 2023 A Comprehensive Review of the Pharmacology, Chemistry, Traditional Uses and Quality Control of Star Anise (Illicium verum Hook. F.): An Aromatic Medicinal Plant. Molecules · PMID 37959797 · DOI |
Narrative review mixed (review) |
Review of the botany, chemistry, pharmacology, traditional uses and quality control of star anise | Star anise (Illicium verum) fruit, its oil and shikimic acid fruit n/a n/a · vs n/a |
The review says 201 chemical constituents have been identified, with the oil and shikimic acid the two most used and studied, and that star anise is used in traditional medicine for warming and pain relief and as a condiment. It concludes the research prospects are broad. Methods, limits and fundingOutcomes: Overview Limitations: We read only the abstract. A review of studies, much of it lab work, does not show human benefit. Funding and conflicts: Not stated in the abstract. Read: abstract |
| s-ema-anise-monograph 2013 European Medicines Agency, HMPC: Community herbal monograph on Pimpinella anisum L., fructus (EMA/HMPC/321184/2012), final, adopted 12 November 2013 · Source |
Authoritative guidance n/a |
n/a n/a n/a n/a · vs n/a |
Traditional herbal tea for mild spasm-type gut complaints with bloating and wind, and as an expectorant in cough with a cold. Use under 12 years has not been established. Not for more than two weeks. Contraindicated in allergy to aniseed, to carrot-family plants (caraway, celery, coriander, dill, fennel) or to anethole. Safety in pregnancy and breastfeeding not established, use not recommended. Interactions: none reported. Allergic skin or breathing reactions can occur, frequency unknown. No overdose reported. Anethole showed weak mutagenic potential in lab tests but is unlikely to be genotoxic in the body; the estragole risk is not considered relevant for short-term use of the tea. Methods, limits and fundingOutcomes: n/a Limitations: Covers aniseed fruit as a herbal tea, not the essential oil, and not star anise. Funding and conflicts: Not applicable. Read: full text | |
| s-ema-estragole 2014 European Medicines Agency, HMPC: Public statement on the use of herbal medicinal products containing estragole (EMA/HMPC/137212/2005 Rev 1), draft revision dated 24 November 2014 · Source |
Authoritative guidance n/a |
n/a n/a n/a n/a · vs n/a |
Estragole is a naturally occurring genotoxic carcinogen (in rodents) with DNA potency similar to safrole. Short-term adult use of herbal medicinal products at the recommended dose is judged not to pose a significant cancer risk, but exposure of young children and pregnant and breastfeeding women should be minimised, and data on skin absorption are missing. Its table lists anise (Pimpinella anisum) essential oil as 1 to 5% estragole and 1 to 4% oil in the fruit, and lists star anise (Illicium verum) among estragole-containing plants. Methods, limits and fundingOutcomes: n/a Limitations: This copy is marked as a draft revision released for consultation. It concerns herbal medicines, not bottled aromatherapy oil. The star anise oil figure in the PDF text is garbled, so it is not quoted. Funding and conflicts: Not applicable. Read: full text | |
| s-gbif-ia 2026 GBIF Backbone: Illicium anisatum L. (species key 7314073), status ACCEPTED, family Schisandraceae · Source |
Database n/a |
n/a n/a n/a n/a · vs n/a |
Accepted name Illicium anisatum L. (Japanese star anise, the toxic look-alike named in the case reports), exact match. Methods, limits and fundingOutcomes: n/a Limitations: Read through the GBIF API on 2026-10-25. Funding and conflicts: Not applicable. Read: API | |
| s-gbif-iv 2026 GBIF Backbone: Illicium verum Hook.fil. (species key 2889756), status ACCEPTED, family Schisandraceae · Source |
Database n/a |
n/a n/a n/a n/a · vs n/a |
Accepted name Illicium verum Hook.fil., family Schisandraceae (older papers write Magnoliaceae), exact match. Methods, limits and fundingOutcomes: n/a Limitations: Read through the GBIF API on 2026-10-25. Funding and conflicts: Not applicable. Read: API | |
| s-gbif-pa 2026 GBIF Backbone: Pimpinella anisum L. (species key 8080300), status ACCEPTED, family Apiaceae · Source |
Database n/a |
n/a n/a n/a n/a · vs n/a |
Accepted name Pimpinella anisum L., carrot family (Apiaceae), exact match. Methods, limits and fundingOutcomes: n/a Limitations: Read through the GBIF API on 2026-10-25. Funding and conflicts: Not applicable. Read: API | |
| s-poison-control Poison Control (US National Capital Poison Center): Essential oils, poisonous when misused · Source |
Authoritative guidance n/a |
n/a n/a n/a n/a · vs n/a |
Misuse of essential oils can cause serious poisoning. Swallowed oils can be poisonous, breathing one into the lungs can cause pneumonia, children have thin skin and immature livers, diluting in a carrier oil is the best way to avoid skin reactions, allergy is a real possibility, and it can be hard to know the species and strength in a bottle. Keep bottles locked away from children and pets. If someone swallows an essential oil call a poison centre (US 1-800-222-1222). Methods, limits and fundingOutcomes: n/a Limitations: Undated page; no anise-specific content. Funding and conflicts: Not applicable. Read: page | |
| s-pph-eo Pet Poison Helpline: Essential oils · Source |
Authoritative guidance n/a |
n/a n/a n/a n/a · vs n/a |
Cats and birds are at greatest risk. Swallowing is the highest-risk route, then skin, then breathing. Common signs are drooling, vomiting, lethargy and irritation. Its list of common poisoning oils does not name anise or star anise. Methods, limits and fundingOutcomes: n/a Limitations: Undated page; no anise-specific content. Not being on the list is not proof of safety. Funding and conflicts: Not applicable. Read: page | |
| s-pubchem-anethole 2026 PubChem: Anethole (CID 637563) and Estragole (CID 8815) · Source |
Database n/a |
n/a n/a n/a n/a · vs n/a |
Anethole CID 637563, formula C10H12O (1-methoxy-4-[(E)-prop-1-enyl]benzene). Estragole CID 8815, formula C10H12O. Methods, limits and fundingOutcomes: n/a Limitations: Read through the PubChem API on 2026-10-25. Funding and conflicts: Not applicable. Read: API |
What we do not know yet
- No human trial of star anise oil was found.
- No poisoning or seizure report for anise or star anise oil itself was found; the star anise cases are about tea and fruit.
- Whether the toxic Japanese star anise reaches star anise oil is not known from the sources read.
- The two anise oil trials come from one group, and neither abstract gives capsule strength, funding or a trial registration.
- No statement from the FDA, NCCIH, LiverTox or LactMed was read.
- Skin absorption of estragole from the oils is unknown (EU statement).
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 3
Share of people free of IBS symptoms
Increase in trials
The share of trial participants who report no IBS symptoms on a visual symptom scale at the end of treatment.
Low certaintyResults and what it means
Why it was measured
The main outcome of the IBS trial; it is reported by the patient.
Statistical vs. clinical meaning
A self-rated symptom score, not a lab test.
Safety implication
Fewer symptoms do not show that the product is safe for babies, in pregnancy or in people with allergy.
| Study | Result | People | Product |
|---|---|---|---|
| 10 | 75% on anise oil capsules vs 35% on placebo vs 52.5% on a peppermint oil medicine (intention-to-treat). |
Depression questionnaire score (Beck Depression Inventory-II)
Decrease in trials
A 21-item self-rated questionnaire; a lower score means less depression.
Very low certaintyResults and what it means
Why it was measured
The main outcome of the depression-in-IBS trial.
Statistical vs. clinical meaning
A self-rated questionnaire, not a lab test.
Safety implication
A lower score does not show that the oil is safe for everyone.
| Study | Result | People | Product |
|---|---|---|---|
| 11 | The abstract reports a significant advantage of anise oil at week 4 and week 6 but gives no scores. |
Head lice cleared
Increase in trials
Whether live lice and eggs were gone after treatment, checked by the study team.
Very low certaintyResults and what it means
Why it was measured
The main outcome of the 2002 lice study.
Statistical vs. clinical meaning
Counted by researchers in an open study.
Safety implication
Clearing lice does not show a product is safe for a child's skin and liver.
| Study | Result | People | Product |
|---|---|---|---|
| 12 | 60 children (92.3%) with the three-oil blend vs 59 children (92.2%) with a pesticide spray; the abstract's totals do not fit. |
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
- Do not swallow anise or star anise oil, and keep both away from children and pets.. Poison Control says misused essential oils can cause serious poisoning, that breathing an oil into the lungs while swallowing can cause pneumonia, and that children's thin skin and immature livers may make them more sensitive. It advises locking bottles away from children and pets. We found no poisoning report for anise oil or star anise oil itself. Two reviews of oils that cause seizures when swallowed (a 1999 survey and a 2019 review) do not name anise or star anise, but they name fennel, which also has anethole, and not being named is not proof of safety. If anyone may have swallowed any, call a poison centre (US 1-800-222-1222) or your emergency number. Regulatory 26 4 1
- Star anise tea has poisoned babies. Chinese star anise can be mixed with toxic Japanese star anise.. A US report describes 7 infants with adverse neurologic reactions after star anise tea given at home, and the authors found evidence that Chinese star anise (Illicium verum) had been contaminated with Japanese star anise (Illicium anisatum). A Swiss report describes a 2-month-old with three seizure-like episodes after bottles of star anise infusion; anisatin, the toxin of Japanese star anise, was found in the baby's urine and the fruit sample held 7800 micrograms per kg against a Swiss limit of 1000. The Swiss authors explain that the two fruits look alike, are often sold broken or ground, and that chemical analysis is usually needed to detect the mix-up. A 2024 case series from Bhutan describes two adults with stomach and nerve symptoms after eating star anise fruit; both recovered with supportive care. All of this is about the fruit as a tea or food, not the essential oil. We found no report on whether the toxic species has turned up in star anise oil. Babies should not be given star anise tea. This page cannot help anyone tell the fruits apart. Case report 8 15 19 23
- Estragole and anethole: the EU committee asks for as little exposure as possible for young children, pregnancy and breastfeeding.. Anise oil is mostly trans-anethole (94.01% and 95.2% in two lab analyses), with a smaller share of estragole (1 to 5% of anise oil in the EU committee's table). The EU herbal committee (HMPC) calls estragole a genotoxic carcinogen in rodents, with DNA potency like safrole. It judged that short-term adult use of herbal medicinal products at the recommended dose does not pose a significant cancer risk, but says exposure of young children and of pregnant and breastfeeding women should be minimised, and that skin absorption data are missing. For aniseed tea, the committee's monograph says the estragole risk is not considered relevant for short-term use because the tea has little, and that anethole showed weak mutagenic potential in lab tests but is unlikely to be genotoxic in the body. Lab and volunteer work shows the body converts both estragole and anethole to reactive breakdown products, anethole to a lesser degree; that shows exposure, not harm. A European food safety panel declined to assess an animal-feed star anise fraction that contains up to 25% estragole. These statements are about herbal medicines and feed additives, not bottled aromatherapy oil, so they do not say the oil is safe. Regulatory 22 21 18 5 9 2 7
- Not recommended in pregnancy, while breastfeeding, or for babies and children.. The EU monograph for aniseed tea says safety in pregnancy and breastfeeding has not been established and use is not recommended, and that use under 12 years has not been established because of too little safety data. A 2021 review of essential oils in pregnancy says using herbs or essential oils in pregnancy is questionable and lists anethole among the constituents it covers; the abstract does not give its finding for anise. These limits are written for aniseed as a tea, not for the oil, and we cannot say the oil is safer. Ask a midwife, doctor or pediatrician. Regulatory 21 6 22
- Skin and breathing allergy to aniseed and anethole is documented; never use the oil undiluted.. The EU monograph lists allergy to aniseed, to carrot-family plants (caraway, celery, coriander, dill, fennel) and to anethole as reasons not to use it, and says allergic reactions of the skin or breathing can occur. A 2025 review lists anise among spices implicated in allergy in children, and a case report describes six years of lip inflammation from anethole in a toothpaste. Poison Control says pure essential oils are potent, that diluting in a carrier oil is the best way to avoid a bad skin reaction, that oils should not go on damaged skin, and that a rash should be washed off and the product stopped. Difficulty breathing after any essential oil is an emergency. Regulatory 21 3 16 26
Side effects 4
| Effect | How often | Severity and recovery | Evidence |
|---|---|---|---|
| Neurologic reactions in infants after star anise tea (seizure-like events, irritability) Tea from the fruit, linked to contamination with Japanese star anise. Not the essential oil. | Not established | severe The Swiss infant recovered over hours; outcomes in the US series are not in the abstract. | Case report 8 15 |
| Stomach and nerve symptoms in adults after eating star anise fruit Two adults in Bhutan. Species and testing are not given in the abstract. | Not established | moderate Both patients were discharged after 24 hours of supportive care. | Case report 19 |
| Skin or breathing allergy to aniseed or anethole Allergy to the plant, carrot-family plants or anethole is listed as a contraindication. | Frequency not known (EU monograph) | mild to severe The lip inflammation case cleared after stopping the flavoured toothpaste. | Regulatory 21 16 3 |
| Poisoning when essential oils are swallowed; pneumonia if breathed into the lungs General essential oil advice; no anise-oil-specific case found. | Not established | severe Depends on the oil and the amount; case examples in Poison Control's page are for camphor and lavender, not anise. | Regulatory 26 |
Liver
We found no report of liver injury in people from anise oil or star anise oil in the sources read; LiverTox was not read. Estragole causes liver tumours in rodents, which is why the EU committee limits it; that is animal evidence. A European panel declined to assess a star anise terpene fraction with up to 25% estragole as animal feed because estragole is a genotoxic carcinogen. 22 7
How often. Not established in people.
Monitoring. Not applicable.
This is a safety connection. It is not evidence that Anise and Star Anise Oil supports liver health.
Medicines and supplements 2
| With | Why it matters | Importance | Evidence | What to do |
|---|---|---|---|---|
| Prescription and over-the-counter medicines, in general medicines-general | The EU aniseed monograph says no interactions have been reported for aniseed tea. Poison Control says essential oils may interact with medications. | No specific interaction was found for anise oil or star anise oil. Absence from the sources read is not proof of safety. | Regulatory Not enough evidence 21 26 | Tell your pharmacist or doctor if you take regular medicines before using any essential oil product. |
| Seizure medicines and epilepsy epilepsy-medicines | Reviews name some essential oils (not anise) as able to trigger seizures when swallowed; fennel, which also contains anethole, is among them. | No report links anise or star anise oil to seizures in the abstracts read. This is an unknown, not a clearance. | Review Not enough evidence 4 1 | If you have epilepsy, ask your neurologist before using any essential oil. |
Who should check first 6
| Situation | Advice | Evidence |
|---|---|---|
| Swallowing the oil, or any product not made to be swallowed | Do not swallow. If a child or pet may have swallowed any, call a poison centre or your emergency number. | Regulatory 26 |
| Allergy to aniseed, anethole, or carrot-family plants (caraway, celery, coriander, dill, fennel) | Do not use (EU monograph contraindication for aniseed tea; the same allergy applies to the oil's main compound). | Regulatory 21 |
| Pregnancy and breastfeeding | Not recommended: safety is not established and EU regulators ask for minimal estragole exposure. Ask a midwife or doctor. | Regulatory 21 22 |
| Babies and children | Keep away. Use under 12 years is not established (EU monograph for the tea), the committee asks for minimal estragole exposure in young children, and star anise tea has poisoned babies. | Case report 21 22 8 15 |
| Undiluted use on the skin, or use on damaged skin | Never use essential oil undiluted. Poison Control: diluting in a carrier oil is the best way to avoid a bad reaction, and oils should not go on damaged skin. Skin absorption of estragole is unknown (EU statement). | Regulatory 26 22 |
| Epilepsy or a history of seizures | No anise-specific report was found, but some essential oils swallowed have caused seizures. Ask a neurologist. | Review 4 1 |
Overdose, product quality and regulators
Summary. Toxicity is described by star anise tea case reports in infants (likely due to a toxic look-alike species), a case series of two adults after eating the fruit, EU findings on estragole in rodents, and general poison-centre advice. No safe or lethal amount of anise or star anise oil is established in the sources read, and none is stated here.
Amounts. No safe amount is established, and this page gives none.
Onset and course. Swiss infant: three seizure-like episodes in the hours after the infusion, the last about 8 hours after the final drink; toxin found in urine at 22 hours and gone at 33 hours. Pets: signs of essential oil poisoning usually appear within 6 to 8 hours (Pet Poison Helpline).
Repeated use. The EU concern about estragole is exposure over time (rodent liver tumours). The aniseed monograph limits tea use to no more than two weeks.
Animal data. Estragole causes liver tumours in rodents (EU statement). Anethole showed weak mutagenic potential in lab tests but is unlikely to be genotoxic in the body (EU aniseed monograph). Lab animal work on the oils themselves was not read.
Toxic parts. Japanese star anise (Illicium anisatum) contains anisatin, a neurotoxin that blocks GABA receptors, according to the French case report. Chinese star anise (Illicium verum) is the spice species, but it has been found mixed with the toxic species.
Not read. LiverTox, LactMed, FDA, NCCIH, RIFM, IFRA, SCCS and Tisserand safety data on anise or star anise oil were not read.
Star anise has a known mix-up problem with a toxic look-alike species, and what is in any essential oil bottle can be unclear.
Adulteration of Chinese star anise with Japanese star anise. Case reports in the US and Switzerland found evidence of mix-ups; the Swiss fruit sample had 7800 micrograms per kg of anisatin against a Swiss maximum tolerance value of 1000. The authors say the fruits look alike, are often sold broken or ground, and chemical analysis is usually needed to detect it. These were tea and fruit, not the oil. 8 15
Two different plants share one name. Anise oil comes from Pimpinella anisum (carrot family); star anise oil comes from Illicium verum (Schisandraceae). Both smell of licorice because both are rich in anethole (anise oil 94.01% and 95.2% in two analyses; one star anise oil 83.68%), but they are different plants with different safety stories. 18 5 13 25 24
Unknown species, strength and contaminants. Poison Control says it can be hard to know the plant species, concentration or contaminants in an essential oil bottle. 26
| Body | Action | Date |
|---|---|---|
| European Medicines Agency, HMPC (EU herbal monograph, aniseed fruit) (European Union) | Traditional herbal tea for mild spasm-type gut complaints with bloating and wind, and as an expectorant in cough with a cold. Use under 12 years has not been established. Not more than two weeks. Contraindicated in allergy to aniseed, carrot-family plants or anethole. Safety in pregnancy and breastfeeding not established; not recommended. Allergic skin or breathing reactions can occur. It covers the fruit as a tea, not the oil. source | 2013-11 |
| European Medicines Agency, HMPC (public statement on estragole) (European Union) | Estragole is a genotoxic carcinogen in rodents. Short-term adult use of herbal medicinal products at the recommended dose does not pose a significant cancer risk, but exposure of young children and of pregnant and breastfeeding women should be minimised; skin absorption data are missing. Lists anise essential oil as 1 to 5% estragole. source | 2014-11 |
| EFSA FEEDAP Panel (opinion on a star anise terpene feed additive) (European Union) | Declined to assess the safety and efficacy of an animal-feed fraction of star anise oil containing up to 25% estragole, because the process enriches a genotoxic carcinogen. source | 2023-10 |
| Poison Control (National Capital Poison Center) (United States) | General essential-oil safety: poisonous if swallowed, dilute for skin, lock away from children and pets, call a poison centre. source | n/d |
| Pet Poison Helpline (United States) | Cats and birds are at greatest risk from essential oils; anise and star anise are not on its list of common poisoning oils. source | n/d |
When to get medical help
- If a child or pet may have swallowed anise or star anise oil, or a baby has had star anise tea, call poison control straight away (US: Poison Help 1-800-222-1222; for pets, a vet or a pet poison line) or your local emergency number. Do not make them vomit.
- Seizure-like movements, stiffening, blue lips, unusual drowsiness, confusion, repeated vomiting or difficulty breathing after swallowing or using any essential oil or star anise tea is an emergency: call your emergency number.
- Swelling of the face or lips, wheezing or a spreading rash after contact is a possible severe allergy: seek urgent help.
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 anise oil or star anise oil safe to swallow?
No. Poison Control says swallowed essential oils can be poisonous, and that breathing an oil into the lungs while swallowing can cause pneumonia. We found no poisoning report for these two oils themselves, but that is not proof of safety. If a child or pet may have swallowed any, call poison control (US: 1-800-222-1222) or your emergency number.
What is the difference between anise oil and star anise oil?
They come from two unrelated plants: aniseed (Pimpinella anisum, carrot family) and star anise (Illicium verum). Both smell of licorice because both are rich in anethole. Their safety stories differ: star anise has a documented mix-up problem with a toxic look-alike fruit, and the infant poisonings were from star anise tea.
Has star anise poisoned babies?
Yes, as tea. A US report describes 7 infants with adverse neurologic reactions after star anise tea given at home, and a Swiss report describes a 2-month-old with three seizure-like episodes after star anise infusion. The authors found evidence of mix-ups with toxic Japanese star anise. Babies should not be given star anise tea. If a baby has symptoms, call your emergency number.
Can I tell toxic star anise from safe star anise?
What is the estragole concern with anise oil?
The EU herbal committee says estragole is a genotoxic carcinogen in rodents. Anise oil is mostly anethole, with 1 to 5% estragole in the committee's table. The committee judged that short-term adult use of herbal medicines at recommended amounts does not pose a significant cancer risk, but asks that young children, pregnant women and breastfeeding women have as little as possible. Skin absorption data are missing. These are statements about herbal medicines, not aromatherapy bottles.
Is anise oil safe for babies and children?
Keep it away. The EU monograph for aniseed tea says use under 12 years has not been established, the estragole statement asks for minimal exposure in young children, and Poison Control notes children's thin skin and immature livers. A 2002 lice study included children aged 6 to 14, but that was a three-oil blend and is not advice. Ask a pediatrician.
Is anise oil safe in pregnancy or breastfeeding?
Can anise oil cause an allergic reaction?
Yes. The EU monograph lists skin or breathing allergy as possible and lists allergy to aniseed, carrot-family plants such as fennel, or anethole as reasons not to use it. Anise is among spices often implicated in allergy in children, and one case report describes six years of lip inflammation from anethole in a toothpaste. Never use the oil undiluted, and stop if a rash appears.
Does anise oil help irritable bowel syndrome?
One 2016 trial of 120 people in Iran found 75% free of IBS symptoms on coated anise oil capsules versus 35% on placebo and 52.5% on a peppermint oil medicine. It is one trial from one group, so the certainty is low, and capsule strength and funding are not in the abstract. It does not show that bottled oil works or is safe to swallow.
Does anise oil help with depression or anxiety?
There is one trial in 120 people with IBS and mild to moderate depression. The abstract reports anise oil beat a peppermint medicine and placebo on a depression questionnaire but gives no numbers, and it may overlap with the IBS trial. The certainty is very low. If your mood is low, talk to a doctor.
Does anise oil get rid of head lice?
A 2002 open study in schoolchildren found a blend of coconut, anise and ylang ylang oils cleared lice about as often as a pesticide spray (92.3% against 92.2%). It had three oils, was not blinded, and the abstract's numbers do not add up, so it cannot be credited to anise oil. Ask a pharmacist about lice treatment.
Are anise and star anise oil safe for pets?
Keep them away. Pet Poison Helpline says cats and birds are at greatest risk from essential oils, and that swallowing is the highest-risk route. Anise and star anise are not on its list of common poisoning oils, but we found no anise-specific pet report. Call a vet or pet poison line after any exposure.
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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 20 PubMed papers, the full EMA aniseed monograph and estragole statement, and the Poison Control and Pet Poison Helpline pages, and checked plant names in GBIF and compounds in PubChem. We did not read a statement from the FDA, NCCIH, LiverTox or LactMed.
- 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.
Sources 28
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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- . European Medicines Agency, HMPC: Community herbal monograph on Pimpinella anisum L., fructus (EMA/HMPC/321184/2012), final, adopted 12 November 2013. . 2013. (full text)
- . European Medicines Agency, HMPC: Public statement on the use of herbal medicinal products containing estragole (EMA/HMPC/137212/2005 Rev 1), draft revision dated 24 November 2014. . 2014. (full text)
- . GBIF Backbone: Illicium anisatum L. (species key 7314073), status ACCEPTED, family Schisandraceae. . 2026. (API)
- . GBIF Backbone: Illicium verum Hook.fil. (species key 2889756), status ACCEPTED, family Schisandraceae. . 2026. (API)
- . GBIF Backbone: Pimpinella anisum L. (species key 8080300), status ACCEPTED, family Apiaceae. . 2026. (API)
- . Poison Control (US National Capital Poison Center): Essential oils, poisonous when misused. . . (page)
- . Pet Poison Helpline: Essential oils. . . (page)
- . PubChem: Anethole (CID 637563) and Estragole (CID 8815). . 2026. (API)