Fennel

Fennel (Foeniculum vulgare)

Close-up of a green flowering plant with small clustered buds, surrounded by green leaves.

Plant family

  • Apiaceae

Parts used

  • Fructus, but often cited as seed (semen)

Typical forms of prescription

  • Infusion

  • Tinctures

  • Syrups

Close-up of a yellow flowering plant with multiple umbrella-shaped clusters of tiny yellow flowers on green stems against a blurred green background.

Fennel (Foeniculum vulgare) - Clinical Snapshot.

Actions

  • Carminative

  • Antispasmodic

  • Anti-inflammatory

  • Digestive

  • Galactagogue (promotes milk production)

  • Hepatic (supports liver function)

  • Anaesthetic (mild numbing effect)

  • Antimicrobial

  • Antitussive (cough suppressant)

  • Expectorant (helps expel mucus)

  • Mucolytic (breaks down mucus)

  • Aperient (mild laxative)

  • Diuretic

  • Oestrogenic (has oestrogen-like effects)

Indications

  • Digestive complaints:

    • Flatulence

    • Colic

    • Indigestion

    • Anorexia (poor appetite)

    • Intestinal cramps

    • Bloating

    • Hiccoughs

    • Nausea

    • Halitosis (bad breath)

    • Heartburn

    • Irritable Bowel Syndrome (IBS)

  • Respiratory conditions:

    • Coughs

    • Bronchitis

    • Asthma

  • Urinary conditions:

    • Cystitis

    • Fluid retention

    • Urinary tract infections

  • Other uses:

    • Conjunctivitis (external use)

    • Galactagogue (promotes milk production)

    • Primary dysmenorrhoea (painful menstruation)

    • Amenorrhoea (absent menstruation)

    • Endometriosis

    • Low libido

    • Premenstrual Syndrome (PMS)

⚠️Cautions / Safety ⚠️

  • Use with caution during pregnancy

Fresh fennel bulb with green stalks and fronds on a wooden cutting board.

Flavonoids

Includes: Rutin, quercetin, kaempferol derivatives
Action: Antioxidant, anti-inflammatory, spasmolytic
Use: Flavonoids in fennel support vascular integrity, reduce tissue inflammation, and may help modulate histamine responses. This reinforces fennel’s usefulness in irritable bowel conditions, seasonal allergies, and mild inflammatory complaints.

Foeniculum vulgare

Phytochemistry and Pharmacology

Coumarins

Includes: Bergapten, umbelliferone (in trace amounts)
Action: Mild anticoagulant, spasmolytic
Use: Coumarins contribute to fennel’s circulatory effects and may offer mild muscle-relaxing benefits, particularly when addressing tense digestion or uterine cramping.

Volatile Oils

Includes: Anethole, fenchone, estragole, limonene
Action: Carminative, antispasmodic, expectorant, galactagogue
Use: These essential oils are responsible for fennel’s sweet, aromatic smell and its classic use in digestive health. They help relax smooth muscle, ease intestinal cramping and bloating, and reduce gas formation. Anethole also has a mild expectorant effect and supports milk production in lactating mothers. Fenchone contributes a slightly bitter note and enhances digestive stimulation.

Phenolic Compounds

Includes: Rosmarinic acid, chlorogenic acid
Action: Antioxidant, hepatoprotective, anti-inflammatory
Use: These compounds provide liver-protective and free radical-scavenging actions, making fennel helpful in detoxification protocols and long-term inflammation management.

Fixed Oils (in seeds)

Includes: Oleic acid, linoleic acid
Action: Nutrient-rich, anti-inflammatory
Use: The seeds contain nutritive oils that support tissue repair and anti-inflammatory processes. While not a primary action, they contribute to fennel's gentle nourishing profile.

A white teacup filled with tea placed on a white saucer, with fennel seeds scattered on the saucer, on a wooden surface.

Traditional use

The Anglo-Saxons used Foeniculum vulgare (fennel) to aid digestion and as a remedy for eye problems, believing it could improve vision and ward off evil spirits. The Romans valued fennel for its ability to ease bloating and indigestion, often in tonics and infusions to promote overall health and strength. The Greeks, including Hippocrates, recommended fennel for weight loss and respiratory ailments, as they believed it helped clear phlegm and improve breathing.

Clinical Description

Fennel is primarily used for its digestive and respiratory properties. The essential oil-rich seeds are carminative, antispasmodic remedies for flatulence, bloating, heartburn and indigestion. It is ideally given as an after-dinner infusion or a few seeds chewed directly. Fennel seed tea is also provided to lactating mothers to improve colic symptoms in babies, as the oils pass through the milk. Because it is also oestrogenic, it also increases milk production. A teaspoon of weak infusion may be given to the baby in non-breastfeeding mothers. Fennel essential oils are also mucolytic, antitussive, and antispasmodic, often found in cough syrups.

A weak infusion is used as a wash for eye inflammations.

Cultivation/Harvesting

Gather ripe seeds on a hot, dry day.

Green fennel plants growing in soil with white bulbous bases and feathery green leaves.

Key Botanical Features of Fennel (Foeniculum vulgare)

Growth

  • Growth Habit: Perennial or biennial herb, growing up to 2 meters (6.5 feet) tall.

  • Stem: Erect, smooth, and hollow, often with a bluish-green tinge.

Leaves

  • Type: Finely divided, feathery, and alternate.

  • Shape: Pinnate with thread-like (filiform) segments.

  • Colour: Bright green, resembling dill but with a more pungent aniseed scent.

Flowers

  • Type: Small, yellow, and grouped in umbrella-shaped umbels (compound inflorescences).

  • Blooming Period: Summer to early autumn.

  • Pollination: Primarily by insects (entomophilous).

Fruits & Seeds

  • Fruit Type: Dry schizocarp, splitting into two ribbed, oval-shaped mericarps (seeds).

  • Size: About 4–10 mm long.

  • Colour: Greenish-brown, turning grey-brown when mature.

  • Aroma: Strong anise or liquorice-like fragrance due to anethole content.

Roots

  • Type: Taproot system.

  • Function: Stores nutrients and supports regrowth in perennial varieties.

Habitat & Growth Conditions

  • Climate: Thrives in warm, temperate, and Mediterranean climates.

  • Soil: Prefers well-drained, loamy, or sandy soil.

  • Sunlight: Requires full sun for optimal growth.

Sustainability/Conservation

Wooden spoon filled with cumin seeds, spilled on a white surface with a jar of cumin seeds and a bowl in the background.
Close-up of a green plant with small yellow-green flower clusters and leafy foliage in the background.
Close-up of bright green feathery plant, showing intricate, fine, needle-like leaves
Green fennel plants growing in soil, with bulbs visible at the base and feathery leaves above.
Fennel bulb with green stalks and fronds on a wooden cutting board
White cup of tea on a saucer with dried fennel seeds on a white plate, placed on a wooden surface.

Sources

Bartram, T. (1998). Bartram’s Encyclopedia of Herbal Medicine. Constable.

Fisher, C. (2009). Materia Medica of Western Herbs, (2018 edition). Finchley Road, London. Aeon Books.

Hedley, C & Shaw, N. (2020). A herbal book of making and taking. Finchley Road, London. Aeon Books.

Hoffmann, D. (2003). Medical Herbalism: The Science and Practice of Herbal Medicine. Healing Arts Press.

McIntyre, A. (2019). The complete herbal tutor, revised and expanded edition. Finchley Road, London. Aeon Books.

Plants of the World Online | Kew Science. (n.d.). Plants of the World Online. https://powo.science.kew.org/

Disclaimer: This page is for educational purposes only. Consult a qualified medical herbalist before using herbs, especially during pregnancy, when trying to conceive, while breastfeeding, for medical conditions, or with children.
Read the full disclaimer → Medical Disclaimer.