Plant Profiler

Fennel (Foeniculum vulgare)

Foeniculum vulgare
Synonyms / Common Names / Related Terms
Adas, adas pedas, anason dulce, aneth doux, anis, Anethum foeniculum, Anthemis cotula (dog fennel), Apaiaceae (parsley family), aptechnyj ukrop, apteegitilliseemne, badesopu, badishep, bitter fennel, carosella, cay thi la, common fennel, edeskomeny, fenchel, fenheli parastie, fenhelis, fenicol, fenikel, fenkel, fenkhel, fenkoli, fenkolo, fennel honey syrup, fennel oil, fenneru, fennika, fennikel, fenouil, fenoun, fenykl, ferula communis (giant fennel), finocchio, finokio, florence fennel, Foeniculi antheroleum, Foeniculum capillaceum, Foeniculum officinale, Foeniculum vulgare, Fructus foeniculi, funcho, garden fennel, guamoori, haras, harilik apteegitill, hinojo, hoehyang, hoehyang-pul, hoi huong, hui xiang, jinten manis, kama, koper wloski, komorac, koper, koromac, large cummin, large fennel, lus an t'saiodh, madhurika, maduru, marac, maratho, mehul, mellet karee, merula obisnuita, mieloi, miur belar, molura, morach, moti saunf, mouri, paciolis, pak chi duanha, pan mohuri, paprastasis pankolis, pedda jilakarra, pennel, perunjiragam, phak si, phong karee, phytoestrogen, razianaj, razianeh, razyana, rezene, samit, samong-saba, saunf, shamaar, shamar, shamari, shamraa, shatpushpa, shoap, shoumar, shumar, siu wuih heung, sladki komarcek, sladkij ukrop, so-hoehyang, sohikirai, sombu, sonf, sopu, spice of the angels, sulpha, sweet cumin, sweet fennel, thian-klaep, tian hi xiang, tieu hoi huong, tihm wuih heung, uikyo, ukrop sladki, Umbilliferae (parsley family), venkel, wariari, wild fennel, wuih heung, xiao hui xiang, yira.

NOTE: Some languages do not differentiate between anise and fennel.

Mechanism of Action


  • Constituents: The major constituent of fennel oil is anethole. Other constituents include alpha pinene, beta myrcene, beta pinene, bitter fenchone, camphene, estragole (methyl-chavicol), fenchone, limonene, p-cymen, and safrole.
  • Fennel is a rich source of beta-carotene and vitamin C4, as well as calcium, magnesium, iron, and lesser amounts of other metal cations3.
  • Anti-carcinogenic and anti-inflammatory effects: Anethole's effects may be mediated by modulation of tumor necrosis factor (TNF) - induced cellular responses. Anethole may interfere with TNF signaling and lead to the activation of NF-kappaB, AP-1, JNK, MEK, and apoptosis. Anethole may suppress NF-kappaB-dependent gene expression induced by TNF. NF-kappaB controls the expression of some genes involved in carcinogenesis and inflammation.5
  • Estragole is a natural constituent of a number of plants including fennel. Estragole is a procarinogen but has minimal carcinogenic risk. To reach full toxicity, estragole must be activated by liver enzymes. Fortunately, other liver enzymes inactivate it, limiting liver damage.6,7,8
  • Anticoagulant effects: Ferrula communis, giant fennel, contains coumarin derivatives that competitively inhibit vitamin K and interfere with blood clotting. In animal studies, internal bleeding and death resulted after ingestion over an extended period of time.2
  • Anti-diabetic effects: Essential oil of fennel seed has been reported to stimulate pancreatic alpha-cells and insulin secretion.9
  • Antispasmodic effects: Fennel seed increases gastrointestinal motility and acts as an antispasmodic at high doses. Fennel extracts produce a reduction in acetylcholine-induced contraction and decreases maximum possible contractility.11
  • Gastric acid secretion properties: Fennel in a concentration of 10% weight/volume increased gastric acid secretion in rats from 0.12mL (basal level) to 0.42mL. The exact mechanism of increasing gastric acid secretion is unknown.
  • Muscle relaxant effects: Fennel oil has demonstrated an increase in resting force of guinea pig tracheal smooth muscle. Anethole may be responsible for the positive inotropic effect.12 In another animal study, sweet fennel oil inhibited acetylcholine-induced contractions of ileal and bladder smooth muscles. The mechanism of action is thought to be due to an inhibition of calcium release from intracellular stores and binding to calcium-binding proteins by the constituents in the fennel oil.13
  • Mucociliary effects: Based on secondary sources, aqueous fennel extracts increased mucociliary activity of the ciliary epithelium in the respiratory tract in frogs.1


  • Insufficient available evidence.

  1. Blumenthal, M. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. 1998;
  2. Shlosberg, A. and Egyed, M. N. Examples of poisonous plants in Israel of importance to animals and man. Arch Toxicol.Suppl 1983;6:194-196. 6578721
  3. Zhu, M., Wong, P. Y., and Li, R. C. Effect of oral administration of fennel (Foeniculum vulgare) on ciprofloxacin absorption and disposition in the rat. J Pharm.Pharmacol 1999;51(12):1391-1396. 10678493
  4. Brinker, F. Herb Contraindications and Drug Interactions. 1998;2nd
  5. Chainy, G. B., Manna, S. K., Chaturvedi, M. M., and Aggarwal, B. B. Anethole blocks both early and late cellular responses transduced by tumor necrosis factor: effect on NF-kappaB, AP-1, JNK, MAPKK and apoptosis. Oncogene 6-8-2000;19(25):2943-2950. 10871845
  6. De Vincenzi, M., Silano, M., Maialetti, F., and Scazzocchio, B. Constituents of aromatic plants: II. Estragole. Fitoterapia 2000;71(6):725-729. 11077188
  7. Iten, F. and Saller, R. [Fennel tea: risk assessment of the phytogenic monosubstance estragole in comparison to the natural multicomponent mixture]. Forsch Komplementarmed Klass Naturheilkd 2004;11(2):104-108. 15138375
  8. Iyer, L. V., Ho, M. N., Shinn, W. M., Bradford, W. W., Tanga, M. J., Nath, S. S., and Green, C. E. Glucuronidation of 1'-hydroxyestragole (1'-HE) by human UDP-glucuronosyltransferases UGT2B7 and UGT1A9. Toxicol.Sci 2003;73(1):36-43. 12657745
  9. Farag, R, Abu-Raiia, S, and Abdel-Moein, N. The essential oils of coriander, common dill, and bitter fennel and their effects on diabetic rats. Bull Fac of Agric, Univ of Cairo 1992;43(1):31-44.
  10. Weizman, Z, Alkrinawi, S, and Goldfarb, D. Efficacy of herbal tea preparation in infantile colic. J Pediatr 1993;122(650):652.
  11. Vasudevan, K., Vembar, S., Veeraraghavan, K., and Haranath, P. S. Influence of intragastric perfusion of aqueous spice extracts on acid secretion in anesthetized albino rats. Indian J Gastroenterol 2000;19(2):53-56. 10812814
  12. Reiter, M. and Brandt, W. Relaxant effects on tracheal and ileal smooth muscles of the guinea pig. Arzneimittelforschung 1985;35(1A):408-414. 4039178
  13. Saleh, M, Hashem, F, and Grace, M. Volatile oil of Egyptian sween fennel (Foeniculum vulgare, var. dulce. Alef.) and its effects on isolated smooth muscles. Pharm Pharmacol Lett 2005;6(1):5-7.

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