Botanical name Foeniculum vulgare Mill. Var. amara
Processing Method Steam Distillation
Color/Consistency A thin, clear to pale yellow liquid.
Aromatic Summary / Note / Strength of Aroma A top note with a medium aroma, Fennel Sweet Essential Oil has a similar to that of black licorice.
Blends With Bergamot, Lavender, Frankincense and Rose.
Also known as Common Fennel, Fennel is an erect growing perennial herb native to southern Europe and the Mediterranean area. Reaching a height of 1.5 meters (approximately 4.5 feet), the plant has yellow flowers. Bitter Fennel was known as fenkle in the Middle Ages, from the Latin foenum meaning 'hay'. The ancients believed it gave one longevity, courage and strength, as well as warded off evil spirits.
The health benefits of Fennel essential oil can be attributed to its properties as an antiseptic, antispasmodic, aperitif, carminative, depurative, diuretic, emmenagogue, expectorant, galactagogue, laxative, stimulant, stomachic, splenic, tonic and vermifuge substance.
The Greek name for fennel is marathon or marathos, and the place of the famous battle of Marathon (whence marathon, the subsequent sports event) literally means a plain with fennel. The word is first attested in Mycenaean Linear B form as ma-ra-tu-wo.
Hydrodistillation (HD) and steam-distillation, or solvent extraction methods of essential oils have some disadvantages like thermal decomposition of extracts, its contamination with solvent or solvent residues and the pollution of residual vegetal material with solvent which can be also an environmental problem.
You must remember that there are two sides to any story and too much of anything is harmful. This is obviously true for fennel as well. Certain components of the fennel essential oil such as Anethol, and a few chemicals present in the plant itself, besides being beneficial, can be dangerous if ingested in too large of a quantity. You must remember that the compounds which can kill bacteria and microbes in low doses can be harmful to you too. Excess use of fennel can cause difficulty breathing, increased palpitations, irregular heartbeat, and various neural problems.
Hazards Drug interaction; reproductive hormone modulation; potentially carcinogenic, based on estragole content; may inhibit blood clotting; skin sensitization if oxidized. Contraindications (all routes): Pregnancy, breastfeeding, endometriosis, estrogen-dependent cancers, children under five years of age.
Cautions (oral) Diabetes medication, anticoagulant medication, major surgery, peptic ulcer, hemophilia, other bleeding disorders.
Maximum adult daily oral dose 54 mg
Maximum dermal use level
EU No limit
Tisserand & Young 1.8%
Our safety advice
We recommend a maximum adult oral dose of 54 mg and a dermal maximum of 1.8%, based on 6.5% estragole content with oral and dermal limits of 0.05 mg/kg and 0.12%.
The Comission E Monograph for fennel oil recommends that it is not used in pregnancy, or “for infants and toddlers”. IFRA recommends a maximum dermal use level for estragole of 0.01% in leave-on or wash-off preparations for body and face. The EU does not restrict estragole.
Adverse skin reactions Undiluted bitter fennel oil was nonphototoxic in hairless mice and swine. The undiluted oil was irritating to rabbits, but was not irritating to mice or pigs; tested at 4% on two panels of 25 volunteers it was not irritating
Cardiovascular effects (E)-anethole inhibits platelet aggregation an essential step in the blood clotting cascade. Sweet fennel oil reduced blood glucose levels in both normal and alloxan-diabetic rats following sc injection at 21.5 mg/kg.
Hepatotoxicity (E)-Anethole has a dose-dependent hepatotoxicity which is due to a metabolite, anethole 10,20-epoxide (AE) and different amounts of AE are produced in different species. High doses of (E)-anethole or AE deplete glutathione but sweet fennel oil, which has a very similar composition to bitter fennel, significantly induced glutathione S-transferase activity in mouse tissues. The amounts of (E)-anethole-rich essential oils used in aromatherapy pose no risk to humans.
Acute toxicity Bitter fennel acute oral LD50 in rats 4.52 mL/kg; acute dermal LD50 in rabbits >5 g/kg.
Carcinogenic/anticarcinogenic potential No information !found for bitter fennel oil. Estragole is a rodent carcinogen when exposure is sufficiently high; (E)-anethole is not a rodent carcinogen; (þ)-limonene is anticarcinogenic.
Drug interactions Antidiabetic or anticoagulant medication, because of cardiovascular effects, above.
The Expanded Commission E Monographs list bitter fennel oil as an oil that should not be used in pregnancy, or for infants and toddlers. No explanation is given. Bitter fennel is the official fennel oil of the European Pharmacopoeia, and should contain >60% (E)-anethole, >15% fenchone, and <5% estragole. It is clearly important to ensure that bitter fennel oil has not oxidized before employing it for therapeutic purposes, although this raises the issue of what oxidized in the oil, and whether anise and sweet fennel oils, which are similar to bitter fennel in composition, might be similarly prone to oxidation. (E)-Anethole is susceptible to oxidation, and its oxidation products, (Z)-anethole, anisaldehyde and anisic ketone, may be skin sensitizing (see (E)-Anethole profile.