Western herbalism
AnisePimpinella anisum
Enteric-coated anise oil left 75% of 120 IBS patients symptom-free against 35% on placebo in one Iranian trial; replication is still missing.
- Botanical name
- Pimpinella anisum
- Part used
- fruit (aniseed) and its essential oil
- Also called
- Aniseed, Anise seed, Anisi fructus, Anisoon (Persian and Unani texts)
- Used in
- Western herbalism
- Taken for
- Gas, Bloating, Cramping and pain, Indigestion
- Sold as
- tea, whole seed, capsules, essential oil, tincture
Anise, the plant and the part used
Anise is the small, ridged fruit (the aniseed) of Pimpinella anisum, an annual of the carrot family (Apiaceae) grown around the Mediterranean and in western Asia. Its aromatic oil is the part most used for the gut.
It is sold as whole or crushed seed for tea, as seed powder, and as essential oil in capsules, including enteric-coated oil capsules that open past the stomach. The European monograph describes the tea as 1 to 3.5 g of whole or freshly crushed aniseed in 150 ml of boiling water.
Two look-alikes cause confusion. Fennel is a related carrot-family plant with a similar anethole-rich flavor; the two are separate herbs, and a person allergic to one is advised to take care with the other. Star anise is a different plant altogether: Illicium verum, a tree of the magnolia family whose star-shaped fruit is used in Chinese cooking and medicine. Studies of star anise do not carry over to aniseed, and this entry covers aniseed only.
Traditional uses, in their own terms
Western herbalism
Aniseed is a classic European and Mediterranean carminative, a remedy for wind. The European Medicines Agency’s herbal committee lists aniseed as a traditional herbal medicine for the symptomatic treatment of mild, spasmodic gastrointestinal complaints including bloating and flatulence, and as an expectorant in cough with a cold, based on long-standing use alone. Authors of an Iranian trial note that anise is well recognized in Traditional Persian Medicine, where textbooks suggest anise oil for bowel disorders and scholars ascribe a favorable effect on gastrointestinal disease to it. The trial authors cite that record as their reason for testing it. Star anise has its own, separate place in Chinese medicine, where a review says it is used for warming yang, dispersing cold, regulating qi and relieving pain.
Compounds, and what the laboratory says about them
The European monograph names anethole, which aniseed shares with fennel, as a reason for allergy contraindication, and notes that estragole is present in only small amounts in aniseed infusions. In preclinical tests, an aqueous aniseed extract was negative in an Ames test of mutagenicity, anethole showed a weak mutagenic potential in non-clinical studies, and the committee judged that anethole and its metabolites are unlikely to be genotoxic in vivo. The sources we read give no laboratory mechanism for the anti-IBS result of anise oil, and the authors of that trial call for studies to find the main mechanism.
Trials in people, with the numbers
Anise has a small number of positive trials, nearly all from one country, with the replication problem that goes with that. A 2020 systematic review of 33 double-blind placebo-controlled trials of Western herbal medicines in irritable bowel syndrome listed Pimpinella anisum oil among the preparations that showed efficacy in a rigorously designed trial, and noted that apart from peppermint oil, aloe vera and asafoetida, none of the positive trials had been replicated.
That trial randomized 120 patients with IBS to enteric-coated anise oil capsules, placebo, or a peppermint oil product, three capsules a day for four weeks. In the intention-to-treat analysis 75% on anise oil, 35% on placebo and 52.5% on peppermint were free of IBS symptoms (P < 0.001), and the number needed to treat was 4; the improvement held at a two-week follow-up.
In functional dyspepsia (postprandial distress syndrome), 107 patients received 3 g of anise powder after each meal or placebo (corn starch) for 4 weeks. Symptom severity scores were 7.04 against 12.30 at week 2, 2.44 against 13.05 at week 4 and 1.08 against 13.30 at week 12 (P = 0.0001 at each point). The effect size is unusually large, the placebo group’s scores rose rather than fell over the study (from 10.96 to 13.30), and the published conclusion contains a wording error about postpartum depression, so we treat it as a result to be repeated.
A Brazilian tea containing anise, fennel, elder and senna shortened colonic transit time in 20 people with constipation, but senna is a stimulant laxative, so that trial does not speak to anise. We could not find a randomized trial of anise tea alone.
| Study | Dose | What it found |
|---|---|---|
| Randomized three-arm double-blind trial, 120 patients with IBS (anise oil vs placebo vs peppermint oil product) PMID 27815079 | Enteric-coated anise oil, 3 capsules a day for 4 weeks | Symptom-free 75% vs 35% placebo vs 52.5% peppermint (P < 0.001); NNT 4 |
| Randomized double-blind trial, 107 patients with postprandial distress syndrome PMID 25767516 | 3 g anise powder after each meal, 4 weeks | FD severity at week 4: 2.44 vs 13.05 on placebo (P = 0.0001); placebo scores did not fall |
| Systematic review of 33 double-blind placebo-controlled trials of Western herbal medicines in IBS PMID 31987249 | Various | Pimpinella anisum oil among the preparations with efficacy in a rigorous trial; most positive trials not replicated |
| Randomized crossover trial, 20 people with chronic constipation (anise, fennel, elder and senna tea; a mixture with a laxative) PMID 20433751 | 5 days | Colonic transit 15.7 vs 42.3 hours on placebo (P < 0.001); small drop in potassium |
The doses on record
The European monograph’s traditional-use dose for adolescents over 12, adults and the elderly is a tea of 1 to 3.5 g of whole or freshly crushed aniseed in 150 ml of boiling water three times daily, for no more than two weeks. It does not advise use under age 12.
Trials used 3 g of aniseed powder after each meal for four weeks in dyspepsia, and three capsules a day of enteric-coated anise oil for four weeks in IBS; the strength of each capsule is not stated in the abstract. The oil is far more concentrated than the seed, so the two doses are not interchangeable.
None of this is a dose recommendation. It is what the literature used, set down so a label can be compared with it; a pharmacist or clinician decides what applies to you.
The safety record
The European monograph names allergic reactions of the skin or respiratory system as the main adverse effect, with frequency unknown, and contraindicates aniseed for people hypersensitive to aniseed, to other carrot-family plants (caraway, celery, coriander, dill, fennel) or to anethole. Safety in pregnancy and breastfeeding has not been established and the monograph does not advise use then. Use under age 12 is not established, partly because of preclinical safety questions about anethole and estragole, which the committee considered not relevant for short-term use by adults in the amounts found in infusions. No overdose cases are on record. The trials we read did not report serious adverse events, though they lasted only four weeks.
Medicines it can interact with
The European monograph reports no interactions for aniseed. We could not find a published interaction study for aniseed or anise oil with any medicine class. The IBS trial compared enteric-coated anise oil with a peppermint oil product, so the cautions about enteric coatings and acid reducers in the peppermint monograph (food, antacids, histamine-2 blockers and proton pump inhibitors can open a coated capsule early) are a reasonable parallel for any coated oil capsule. The catalog’s own drug rules for anise are listed automatically on this page.
The interaction rules the quiz applies to anise
These are the medicines the quiz pairs with a caution or an exclusion for this herb, taken from published interaction references:
- acetaminophen (flagged to check)
- acetaminophen / codeine (flagged to check)
- canagliflozin (flagged to check)
- conjugated estrogens (flagged to check)
- dapagliflozin (flagged to check)
- diazepam (flagged to check)
- drospirenone / ethinyl estradiol (flagged to check)
- empagliflozin (flagged to check)
- estradiol (flagged to check)
- ethinyl estradiol / levonorgestrel (flagged to check)
- ethinyl estradiol / norethindrone (flagged to check)
- ethinyl estradiol / norgestimate (flagged to check)
- etonogestrel / ethinyl estradiol (flagged to check)
- fluoxetine (flagged to check)
- glimepiride (flagged to check)
- glipizide (flagged to check)
- glyburide (flagged to check)
- imipramine (flagged to check)
- and 10 more
Where anise turns up in the catalog
Anise appears on the labels below, alone or inside a blend; each product page gives the printed amount, the evidence for that product and the review picture.
Which product, for your symptoms?
The quiz weighs your symptoms and medicines against every product researched here, anise products included, and shows its working.
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The questions that come up
Does anise help IBS?
One three-arm trial of 120 patients found enteric-coated anise oil left 75% symptom-free against 35% on placebo. A systematic review noted that the finding has not been replicated. Treat it as promising but unconfirmed.
Is anise the same as fennel?
No. They are different carrot-family plants that share the aromatic compound anethole. The European monograph lists allergy to fennel as a reason for care with aniseed.
Is star anise the same as anise?
No. Star anise is Illicium verum, a magnolia-family tree used in Chinese cooking and medicine, and aniseed is the fruit of Pimpinella anisum. The studies here concern aniseed only.
How long can anise tea be used?
The European monograph limits traditional use to two weeks in adults and adolescents over 12. It does not advise use under age 12, or in pregnancy and breastfeeding.
Sources
- Mosaffa-Jahromi M et al., "Efficacy and safety of enteric coated capsules of anise oil to treat irritable bowel syndrome", J Ethnopharmacol 2016 pubmed.ncbi.nlm.nih.gov/27815079
- Ghoshegir SA et al., "Pimpinella anisum in the treatment of functional dyspepsia: A double-blind, randomized clinical trial", J Res Med Sci 2015;20(1):13-21 pubmed.ncbi.nlm.nih.gov/25767516
- Hawrelak JA et al., "Western herbal medicines in the treatment of irritable bowel syndrome: A systematic review and meta-analysis", Complement Ther Med 2020 pubmed.ncbi.nlm.nih.gov/31987249
- Picon PD et al., "Randomized clinical trial of a phytotherapic compound containing Pimpinella anisum, Foeniculum vulgare, Sambucus nigra, and Cassia augustifolia for chronic constipation", BMC Complement Altern Med 2010;10:17 pubmed.ncbi.nlm.nih.gov/20433751
- European Medicines Agency HMPC, Community herbal monograph on Pimpinella anisum L., fructus (Final), EMA/HMPC/321184/2012 www.ema.europa.eu/en/documents/herbal-monograph/final-community-herbal-monograph-pimpinella-anisum-l-fructus_en.pdf
- Zou Q et al., "A Comprehensive Review of the Pharmacology, Chemistry, Traditional Uses and Quality Control of Star Anise (Illicium verum Hook. F.): An Aromatic Medicinal Plant", Molecules 2023;28(21) pubmed.ncbi.nlm.nih.gov/37959797
- European Medicines Agency HMPC, European Union herbal monograph on Mentha x piperita L., aetheroleum (Final, Revision 1), EMA/HMPC/522410/2013 (cited for the enteric-coated capsule cautions) www.ema.europa.eu/en/documents/herbal-monograph/european-union-herbal-monograph-mentha-x-piperita-l-aetheroleum-revision-1_en.pdf