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Fennel (Foeniculum vulgare)

Foeniculum vulgare
Evidence Level
Limited
6 Clinical Trials
4 Documented Benefits
2/5 Evidence Score

Fennel (Foeniculum vulgare) is a plant in the carrot and celery family (Apiaceae) whose dried fruits, sold as fennel seed, are used as a spice and as an herbal tea. Its essential oil contains trans-anethole, fenchone and estragole. European Medicines Agency monographs on sweet and bitter fennel recognize fennel tea only as a traditional remedy, based on long use, for mild spasmodic digestive complaints such as bloating and gas, minor menstrual cramps, and coughs with colds. The human trials, almost all small and from Iran, tested fennel oil capsules, seed powder or oil drops for menopausal symptoms and menstrual pain, and results differed from trial to trial. One trial tested a fennel seed oil emulsion in infants with colic. The EMA advises keeping estragole intake as low as practical and does not recommend fennel in pregnancy, while breastfeeding or under age 4.

Studied Dose Trials: 100 mg fennel soft capsules two or three times daily for 8 to 12 weeks; 30 mg fennel oil capsules twice daily for 8 weeks; seed powder 2 g a day for 8 weeks; 30 mg oil capsules four times daily for 3 days per cycle. EMA tea: 1.5 g seed in 250 ml boiling water 3 times daily, up to 2 weeks.
Active Compound Essential oil containing trans-anethole, fenchone and estragole. In one trial, 100 mg soft capsules held 30% fennel, standardized to 21 to 27 mg anethole.

Benefits

Menopause symptom scores in postmenopausal women

In a 90-woman placebo-controlled trial, soft capsules containing 100 mg fennel twice daily for 8 weeks lowered Menopause Rating Scale scores more than placebo, and a pooled analysis of two placebo trials (145 women) favored fennel. A 50-woman, 3-month trial found no difference from placebo, as both groups improved, and reviewers rated the trials' risk of bias as concerning.

Supported by Trial 1, Trial 4

Menstrual cramp pain in young women

In placebo-controlled trials in women in Iran, fennel oil or fennel capsules taken by mouth lowered menstrual pain more than placebo in five of seven. Pooled (468 women), they favored fennel, but results varied widely, small positive studies may be overrepresented, and an independent review rated the evidence low quality. The EMA lists minor menstrual spasm as a traditional use.

Supported by Trial 6, Trial 1

Gas and bloating: traditional EU herbal tea use

European Medicines Agency monographs on sweet and bitter fennel accept fennel tea (1.5 g seed in 250 ml boiling water, three times daily, for up to 2 weeks in adults and adolescents) as a traditional herbal medicine for mild spasmodic digestive complaints including bloating and flatulence. This status rests on long-standing use, not on clinical trials.

Supported by Trial 4, Trial 1

Infant crying time with a fennel seed oil emulsion

The EMA does not recommend fennel under age 4 for lack of data, so this result is not advice to give it to babies. In one trial of 125 infants aged 2 to 12 weeks with colic, a fennel seed oil emulsion ended colic by crying-time criteria in 65% of infants versus 23.7% on placebo. No side effects were reported. The trial ran at two clinics in St. Petersburg, Russia.

Supported by Trial 1, Trial 2

Mechanism of action

1

Hormone levels in menopause trials

In one 125-woman trial, fennel oil capsules lowered FSH and raised estradiol compared with placebo after 8 weeks, while a trial of fennel seed powder found no significant estradiol difference between groups. How fennel might affect these hormones has not been established in people.

2

Stomach muscle relaxation (lab tissue)

In guinea pig stomach muscle strips, freshly brewed fennel tea relaxed the upper stomach (fundus and corpus) and strengthened contractions in the lower stomach (antrum). The relaxation was blocked by a drug that stops calcium entry into muscle cells. These are lab tissue findings only.

3

Activity reported in lab and animal studies

Reviews of fennel list antibacterial, antioxidant, anti-inflammatory and pain-relieving activity in lab and animal studies. These effects have not been measured as outcomes in the human trials cited here.

Clinical trials

1
Fennel Soft Capsules vs Placebo for Menopausal Symptoms: 90-Woman RCT
PubMed

Triple-blind, randomized, placebo-controlled trial in Tehran, Iran; soft capsules containing 100 mg fennel or placebo, 2 a day for 8 weeks, with 2 weeks of follow-up; outcome Menopause Rating Scale. One author lists an affiliation with the Barij Medicinal Herbs Research Center. (Rahimikian et al. 2017, Menopause)

90 postmenopausal women aged 45 to 60 (45 fennel, 45 placebo).

Menopause Rating Scale scores fell with fennel but not with placebo, and the groups differed at weeks 4, 8 and 10 (P < 0.001), including 2 weeks after stopping. The authors reported no serious side effects and called for larger trials.

2
Fennel Seed Powder vs Starch Capsules: 80-Participant RCT
PubMed

Randomized trial with a starch capsule control group at a gynecology clinic in Yasuj, Iran, in postmenopausal women aged 45 to 60; four capsules a day of fennel seed powder (2 g in total) or starch for 8 weeks; outcomes Kupperman menopausal index, Hurlbert index of sexual desire and serum estradiol. The abstract gives P < 0.05 for the symptom score change without saying whether it compares the two groups. (Ghaffari et al. 2020, Menopause)

80 participants aged 45 to 60, randomized into two equal groups.

Kupperman index scores fell from 30.8 to 19 with fennel and from 31.2 to 26.4 with starch capsules. Sexual desire and estradiol levels did not differ significantly between groups. The abstract does not report adverse events.

3
Fennel Oil vs Evening Primrose Oil vs Placebo After Menopause: 125-Woman RCT
PubMed

Triple-blind, randomized, 3-arm trial in Iran; capsules of 30 mg fennel oil, 1,000 mg evening primrose oil, or soy starch placebo, 2 a day for 8 weeks; outcomes FSH, estradiol and Menopause Rating Scale. Barij Essence coded the capsules and is listed with Shiraz University of Medical Sciences as a funder. (Ghavi et al. 2023, Iran J Nurs Midwifery Res)

125 postmenopausal women aged 45 to 60 who completed the trial (43 fennel, 42 evening primrose oil, 40 placebo).

Total Menopause Rating Scale scores ended 2.17 points lower with fennel than placebo (P < 0.001, adjusted for age, age at menopause and BMI), but only the psychological subscale changed; physical and urogenital subscales did not. FSH fell and estradiol rose with fennel compared with placebo (P < 0.001). The abstract says scale scores differed between groups at baseline, while the paper's table shows similar starting scores.

4
Fennel Capsules vs Placebo Over 3 Months: 50-Participant RCT With High Placebo Response
PubMed

Double-blind, randomized, placebo-controlled trial in postmenopausal women in Mashhad, Iran; 100 mg soft capsules (30% fennel, standardized to 21 to 27 mg anethole) or matching placebo three times daily for 3 months; outcome Menopause-Specific Quality of Life questionnaire. Barij Essence supplied the capsules and Mashhad University of Medical Sciences funded the study. Sleep results were published separately by Afiat et al. 2018 in J Menopausal Med. (Ghazanfarpour et al. 2018, J Turk Ger Gynecol Assoc)

50 participants in Mashhad, Iran (25 fennel, 25 placebo).

Both groups improved on most questionnaire items, including flushing and sweating scores, and the groups did not differ on any item except coughing or sneezing while urinating (P = 0.03). The authors attributed the lack of difference to a high placebo response. No adverse effects or dropouts were reported. A companion paper on the same 50 participants (same dates and ethics approval) found no difference in Pittsburgh sleep quality scores between groups (P = 0.439).

5
Fennel vs Placebo for Mood Symptoms: 60-Participant RCT
PubMed

Double-blind, randomized, placebo-controlled trial in postmenopausal women in Iran; outcomes Hospital Anxiety and Depression Scale and Zung Self-Rating Depression Scale. (Ghazanfarpour et al. 2018, J Obstet Gynaecol)

60 participants.

Anxiety and depression scores did not fall significantly in the group as a whole. In the subgroup with a depression or anxiety disorder, the authors report borderline or significant improvement.

6
Fennel Oil Capsules vs Placebo for Menstrual Pain: 50-Participant RCT
PubMed

Double-blind, placebo-controlled trial at Babol University of Medical Sciences, Iran, in unmarried young women with moderate or severe primary dysmenorrhea; capsules of 30 mg fennel essential oil or wheat flour, four times daily for the first 3 days of the period, for 2 cycles. The methods name only a paired t test. Barij Essence produced the fennel and placebo capsules, and Babol University of Medical Sciences funded the project. (Omidvar et al. 2012, Ayu)

50 young women aged 15 to 24 who completed treatment, divided into two groups.

Menstrual pain intensity was lower with fennel than placebo on each of the first 3 days of both cycles (P < 0.01). 52% on fennel rated their relief as excellent, versus 8% on placebo.

Side effects and drug interactions

Common Potential side effects

Allergy: the EMA lists hypersensitivity to fennel, anethole, other Apiaceae plants (aniseed, caraway, celery, coriander, dill) or mugwort pollen as reasons not to use it. Allergic skin or breathing reactions can occur; their frequency is not known.
Estragole: this minor constituent is a genotoxic carcinogen in rodents (liver tumors in mice). The EMA says exposure should be kept as low as practically achievable and limits traditional fennel products to 2 weeks in adults. In 42 Austrian retail fennel teas, estimated estragole intake varied widely, and just over half had a margin of exposure below 10,000, the level the authors use to flag a potential risk; they note these teas are usually drunk only briefly.
Pregnancy and breastfeeding: the EMA does not recommend fennel because safety has not been established, notes that trans-anethole passes into breast milk, and sets an estragole limit of 0.05 mg a day for these groups. An aqueous fennel seed extract caused birth defects in pregnant mice.
Children: the EMA does not recommend fennel tea under age 4 for lack of data, or for menstrual cramps under age 12; for ages 4 to 12 it applies an estragole limit of 1.0 microgram per kg of body weight a day.
In trials, reported side effects were few, but most menstrual pain trials did not assess them. In one trial of fennel oil drops, 5 of 30 women withdrew because of the smell and 1 reported a mild increase in menstrual flow.
Hormone-sensitive conditions: in one trial fennel oil capsules lowered FSH and raised estradiol compared with placebo, so people with hormone-sensitive conditions should check with a clinician before regular use.

Important Drug interactions

The EMA monographs on sweet and bitter fennel list no reported drug interactions.
Ciprofloxacin: in rats, fennel extract given with ciprofloxacin cut peak blood levels by 83% and relative bioavailability to about half, likely because metal ions in the extract bind the drug. The authors advise spacing the doses. This was an animal study.
Hormone therapy, hormonal birth control, tamoxifen or aromatase inhibitors: one trial found fennel changed FSH and estradiol compared with placebo, so an effect on hormone treatments is possible but untested. Check with a clinician before combining them.

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Frequently asked questions about Fennel (Foeniculum vulgare)

What is Fennel used for?

Fennel seed is used as a spice and as a tea. The EMA recognizes fennel tea as a traditional remedy for mild spasmodic digestive complaints such as bloating and gas, minor menstrual cramps and coughs with colds. Small trials, mostly from Iran, have tested fennel capsules for menopausal symptoms and menstrual pain.

Does fennel help with gas and bloating?

Fennel tea is accepted in the EU as a traditional herbal medicine for mild bloating and gas, based on long use rather than trials. In guinea pig stomach tissue, fennel tea relaxed the upper stomach muscle. The adult placebo-controlled trials cited here studied menopausal and menstrual symptoms, not bloating.

What is the recommended dosage of Fennel?

There is no established supplement dose. The EMA traditional tea is 1.5 g of seed in 250 ml of boiling water, three times daily, for up to 2 weeks in adults and adolescents. Trials used soft capsules of 100 mg fennel two or three times daily for 8 to 12 weeks, 2 g of seed powder a day, or 30 mg oil capsules four times daily during menstruation.

Is Fennel safe, and does it have side effects?

Side effects in trials were few, but many trials did not track them. The EMA notes possible allergic reactions, advises against use in pregnancy, while breastfeeding and under age 4, limits traditional products to 2 weeks, and says exposure to estragole, which caused liver tumors in mice, should be kept as low as practical. People allergic to celery, dill, related plants or mugwort pollen should avoid it.

Does fennel change hormone levels?

In one 125-woman trial, fennel oil capsules lowered FSH and raised estradiol compared with placebo over 8 weeks. A trial of 2 g fennel seed powder a day found no significant difference in estradiol. People using hormone therapy or with hormone-sensitive conditions should ask a clinician before regular use.

What is Fennel?

Fennel (Foeniculum vulgare) is a plant in the carrot and celery family (Apiaceae) whose dried fruits, sold as fennel seed, are used as a spice and as an herbal tea. Its essential oil contains trans-anethole, fenchone and estragole.

Does Fennel interact with any medications?

Possible interactions include: The EMA monographs on sweet and bitter fennel list no reported drug interactions. Ciprofloxacin: in rats, fennel extract given with ciprofloxacin cut peak blood levels by 83% and relative bioavailability to about half, likely because metal ions in the extract bind the drug. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for Fennel?

NutraSmarts rates the evidence for Fennel as Limited (2 out of 5). It is backed by 6 study summaries and 21 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(21 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Lee HW, Ang L, Lee MS, Alimoradi Z, Kim E. Fennel for Reducing Pain in Primary Dysmenorrhea: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Nutrients. 2020;12(11):3438. doi: 10.3390/nu12113438.PubMedUsed to support: Systematic review of 12 randomized trials of oral fennel for primary dysmenorrhea, all from Iran. Against placebo, 7 trials (468 women) pooled to favor fennel (SMD -3.27, 95% CI -5.28 to -1.26), with 5 positive and 2 negative and very high heterogeneity (I2 98%); funnel plots suggested publication bias, and only 3 trials assessed adverse events.
  2. Shahrahmani H, Ghazanfarpour M, Shahrahmani N, Abdi F, Sewell RDE, Rafieian-Kopaei M. Effect of fennel on primary dysmenorrhea: a systematic review and meta-analysis. J Complement Integr Med. 2021;18(2):261-269. doi: 10.1515/jcim-2019-0212.PubMedUsed to support: Systematic review and meta-analysis of 12 trials: fennel lowered dysmenorrhea pain intensity versus placebo (SMD -0.632, 95% CI -0.827 to -0.436, 7 articles, I2 0%). Trial quality was scored with the Jadad scale.
  3. Namavar Jahromi B, Tartifizadeh A, Khabnadideh S. Comparison of fennel and mefenamic acid for the treatment of primary dysmenorrhea. Int J Gynaecol Obstet. 2003;80(2):153-7. doi: 10.1016/s0020-7292(02)00372-7.PubMedUsed to support: Comparison without placebo in 30 young women with moderate to severe dysmenorrhea: an untreated cycle, a mefenamic acid cycle and a cycle of 2% fennel fruit essence (25 drops every 4 hours) by mouth. Pain fell in both treated cycles compared with the untreated cycle; 5 of 30 withdrew because of fennel's odor and 1 reported a mild increase in menstrual flow.
  4. Pattanittum P, Kunyanone N, Brown J, Sangkomkamhang US, Barnes J, Seyfoddin V, Marjoribanks J. Dietary supplements for dysmenorrhoea. Cochrane Database Syst Rev. 2016;3(3):CD002124. doi: 10.1002/14651858.CD002124.pub2.PubMedUsed to support: Cochrane review of 27 trials of dietary supplements for dysmenorrhea, all evidence judged low or very low quality. For fennel versus placebo it found one usable trial (43 women; MD -0.34 points, 95% CI -0.74 to 0.06), which did not show a clear effect.
  5. Rafieian F, Amani R, Rezaei A, Karaça AC, Jafari SM. Exploring fennel (Foeniculum vulgare): Composition, functional properties, potential health benefits, and safety. Crit Rev Food Sci Nutr. 2024;64(20):6924-6941. doi: 10.1080/10408398.2023.2176817.PubMedUsed to support: Narrative review of fennel's composition, toxicology and pharmacology, listing antibacterial, antifungal, antioxidant, anti-inflammatory and antinociceptive activity in lab and animal studies. Background only.
  6. Rahimikian F, Rahimi R, Golzareh P, Bekhradi R, Mehran A. Effect of Foeniculum vulgare Mill. (fennel) on menopausal symptoms in postmenopausal women: a randomized, triple-blind, placebo-controlled trial. Menopause. 2017;24(9):1017-1021. doi: 10.1097/GME.0000000000000881.PubMedUsed to support: Triple-blind trial in 90 postmenopausal women in Tehran: soft capsules containing 100 mg fennel, 2 a day for 8 weeks, lowered Menopause Rating Scale scores versus placebo at weeks 4, 8 and 10 (P < 0.001). One author lists a Barij Medicinal Herbs Research Center affiliation.
  7. Lee HW, Ang L, Kim E, Lee MS. Fennel (Foeniculum vulgare Miller) for the management of menopausal women's health: A systematic review and meta-analysis. Complement Ther Clin Pract. 2021;43:101360. doi: 10.1016/j.ctcp.2021.101360.PubMedUsed to support: Systematic review of 7 randomized trials of fennel in menopausal women with concerning risk of bias. Two placebo-controlled trials pooled to favor fennel for menopausal symptoms (n = 145, SMD -1.32, 95% CI -1.76 to -0.87); other trials did not show benefit for sexual function, quality of life or psychological health. No serious adverse events were reported.
  8. Ghazanfarpour M, Najafi MN, Sharghi NB, Mousavi MS, Babakhanian M, Rakhshanded H. A double-blind, placebo-controlled trial of Fennel (Foeniculum vulgare) on menopausal symptoms: A high placebo response. J Turk Ger Gynecol Assoc. 2018;19(3):122-127. doi: 10.4274/jtgga.2017.0124.PubMedUsed to support: Double-blind trial in 50 postmenopausal women in Mashhad: 100 mg fennel soft capsules three times daily for 3 months did not differ from placebo on any menopausal symptom except coughing or sneezing when urinating (P = 0.03); both groups improved. Barij Essence supplied the capsules.
  9. Ghaffari P, Hosseininik M, Afrasiabifar A, Sadeghi H, Hosseininik A, Tabatabaei SM, Hosseini N. The effect of Fennel seed powder on estradiol levels, menopausal symptoms, and sexual desire in postmenopausal women. Menopause. 2020;27(11):1281-1286. doi: 10.1097/GME.0000000000001604.PubMedUsed to support: Randomized trial in 80 postmenopausal women in Yasuj, Iran: 2 g fennel seed powder a day for 8 weeks lowered Kupperman scores from 30.8 to 19, versus 31.2 to 26.4 on starch capsules (P < 0.05, not stated to be a between-group comparison); sexual desire and estradiol did not differ significantly between groups.
  10. Ghavi F, Shakeri F, Farahnaz H, Abdolahian S. Comparison of the Effect of Fennel and Evening Primrose Oil on Menopausal Problems and Hormonal Levels: A Randomized Controlled Trial. Iran J Nurs Midwifery Res. 2023;28(4):430-435. doi: 10.4103/ijnmr.ijnmr_149_22.PubMedUsed to support: Triple-blind 3-arm trial in 125 postmenopausal women: 30 mg fennel oil capsules twice daily for 8 weeks lowered FSH, raised estradiol and lowered Menopause Rating Scale scores versus placebo (P < 0.001), with the change confined to the psychological subscale. The abstract reports a baseline score difference that the full-text table does not show. Funded in part by Barij Essence, which coded the capsules.
  11. Afiat M, Dizavandi FR, Kargarfard L, Vahed SHM, Ghazanfarpour M. Effect of Foeniculum Vulgare (Fennel) on Sleep Quality of Menopausal Women: A Double-blinded, Randomized Placebo-controlled Trial. J Menopausal Med. 2018;24(3):204-209. doi: 10.6118/jmm.2018.24.3.204.PubMedUsed to support: Double-blind trial in 50 menopausal women in Mashhad, the same trial reported by Ghazanfarpour 2018 (J Turk Ger Gynecol Assoc): 3 months of fennel capsules did not change total Pittsburgh Sleep Quality Index scores versus placebo (P = 0.439); sleep duration showed a trend (P = 0.059). Barij Essence supplied the capsules.
  12. Ghazanfarpour M, Mohammadzadeh F, Shokrollahi P, Khadivzadeh T, Najaf Najafi M, Hajirezaee H, Afiat M. Effect of Foeniculum vulgare (fennel) on symptoms of depression and anxiety in postmenopausal women: a double-blind randomised controlled trial. J Obstet Gynaecol. 2018;38(1):121-126. doi: 10.1080/01443615.2017.1342229.PubMedUsed to support: Double-blind trial in 60 postmenopausal women: fennel did not significantly lower anxiety or depression scores overall; the authors report borderline or significant improvement in the subgroup with a depression or anxiety disorder.
  13. Omidvar S, Esmailzadeh S, Baradaran M, Basirat Z. Effect of fennel on pain intensity in dysmenorrhoea: A placebo-controlled trial. Ayu. 2012;33(2):311-3. doi: 10.4103/0974-8520.105259.PubMedUsed to support: Placebo-controlled trial in 50 young women with dysmenorrhea: 30 mg fennel essential oil capsules four times daily for 3 days per cycle, for 2 cycles, lowered pain intensity versus wheat flour capsules (P < 0.01). Barij Essence produced the capsules.
  14. Alexandrovich I, Rakovitskaya O, Kolmo E, Sidorova T, Shushunov S. The effect of fennel (Foeniculum Vulgare) seed oil emulsion in infantile colic: a randomized, placebo-controlled study. Altern Ther Health Med. 2003;9(4):58-61..PubMedUsed to support: Randomized placebo-controlled trial in 125 infants aged 2 to 12 weeks with colic in St. Petersburg: fennel seed oil emulsion eliminated colic by Wessel criteria in 65% versus 23.7% on placebo (P < 0.01). No side effects were reported.
  15. Yaralizadeh M, Abedi P, Najar S, Namjoyan F, Saki A. Effect of Foeniculum vulgare (fennel) vaginal cream on vaginal atrophy in postmenopausal women: A double-blind randomized placebo-controlled trial. Maturitas. 2016;84:75-80. doi: 10.1016/j.maturitas.2015.11.005.PubMedUsed to support: Topical product, not oral fennel: in 60 postmenopausal women, a 5% fennel vaginal cream applied daily for 8 weeks improved vaginal cell maturation and pH versus placebo cream. Listed for completeness; this page covers oral use only.
  16. Mihats D, Pilsbacher L, Gabernig R, Routil M, Gutternigg M, Laenger R. Levels of estragole in fennel teas marketed in Austria and assessment of dietary exposure. Int J Food Sci Nutr. 2017;68(5):569-576. doi: 10.1080/09637486.2016.1262334.PubMedUsed to support: Analysis of 42 fennel teas sold in Austria: estimated estragole exposure ranged widely (infants 0.008 to 20.78 micrograms per kg a day); margins of exposure were above 10,000 for nearly half of the teas, leaving others below that level, though the authors note teas are usually used only briefly.
  17. Zhu M, Wong PY, Li RC. Effect of oral administration of fennel (Foeniculum vulgare) on ciprofloxacin absorption and disposition in the rat. J Pharm Pharmacol. 1999;51(12):1391-6. doi: 10.1211/0022357991777218.PubMedUsed to support: Rat study: aqueous fennel extract given with oral ciprofloxacin lowered its peak plasma level by 83% and relative bioavailability to 0.52, possibly through chelation by metal cations in the extract; the authors advise a dosing interval.
  18. Annahazi A, Kuch B, Ridzal L, Mansouri N, Hosni I, Schemann M. Fennel Tea Has a Region-Specific Effect on the Motility of the Stomach. Neurogastroenterol Motil. 2025;37(12):e70201. doi: 10.1111/nmo.70201.PubMedUsed to support: Guinea pig stomach muscle strips: fennel tea relaxed the fundus and corpus and increased antral contraction amplitude; relaxation was blocked by a store-operated calcium entry blocker. Lab tissue only.
  19. European Medicines Agency, Committee on Herbal Medicinal Products (HMPC). European Union herbal monograph on Foeniculum vulgare Miller subsp. vulgare var. dulce (Mill.) Batt. & Trab., fructus (EMEA/HMPC/372839/2016), Final, Revision 1. European Medicines Agency. 2024;Adopted 31 January 2024..SourceUsed to support: Not PubMed-indexed (official EU monograph on sweet fennel). Traditional use only, as tea for mild spasmodic digestive complaints including bloating and flatulence, minor menstrual spasm and cough with colds; adults 1.5 g in 250 ml three times daily, up to 2 weeks; not recommended under 4 years or in pregnancy and lactation; trans-anethole is excreted in breast milk; allergic reactions possible; estragole limits for children and pregnant or breastfeeding women; mouse teratogenicity of an aqueous extract noted.
  20. European Medicines Agency, Committee on Herbal Medicinal Products (HMPC). European Union herbal monograph on Foeniculum vulgare Miller subsp. vulgare var. vulgare, fructus (EMA/HMPC/372841/2016), Final, Revision 1. European Medicines Agency. 2024;Adopted 31 January 2024..SourceUsed to support: Not PubMed-indexed (official EU monograph on bitter fennel). Same traditional indications, posology, 2-week limit, contraindications (Apiaceae, anethole or mugwort pollen hypersensitivity), pregnancy, lactation and child restrictions and estragole limits as the sweet fennel monograph; no interactions reported.
  21. European Medicines Agency, Committee on Herbal Medicinal Products (HMPC). Public statement on the use of herbal medicinal products containing estragole (EMA/HMPC/137212/2005 Rev 1 Corr 1), Final. European Medicines Agency. 2023;Revision 1 adopted 22 September 2021; corrected 12 May 2023..SourceUsed to support: Not PubMed-indexed (official EU public statement). Estragole, found in fennel and anise, is a genotoxic carcinogen in rodents; intake from herbal medicines in the general population should be as low as practically achievable, with use limited to 14 days; guidance values of 0.05 mg a day for pregnant and breastfeeding women and 1.0 microgram per kg body weight for children up to 11.