Foeniculum Vulgare var. Dulce

Photograph by Liisa Shunn

Sweet Fennel

If you've been to an Indian restaurant, you might have noticed what looked like a bowl of caraway seeds where a bowl of peppermints would normally be. Those are fennel seeds, and they do what a peppermint wheel does, only better -- freshen your breath. Fennel, as a plant, is odd to Americans: its bulbs resemble a fat celery stalk, but its flavor is subtly licorice-like. The entire plant can be used -- the feathery leaves are used as an herb, the seeds are used as a spice, and the bulb is a vegetable good in roasts, casseroles, or even in a stir fry. For our purposes, we will be looking at the essential oil that is steam distilled from fennel's seeds.

What is Fennel?

Fennel essential oil, as stated, is steam distilled from the crushed seeds of the Foeniculum Vulgare var. Dulce, or Sweet Fennel, plant. Fennel comes in two varieties, and both have medicinal properties. The variety we are discussing is Sweet Fennel, but there is also a Bitter variety, Foeniculum Vulgare var. Vulgare (or Amarga). Bitter Fennel oil has a high percentage of fenchone, a ketone, which is excellent for bronchial congestion and breathing issues, but can be toxic in very small amounts. Please make sure you are using the safer Fennel oil by checking the Latin name.

How do you use it?

When thinking of Fennel, I associate it with three therapeutic actions: lung congestion and difficulty breathing, dyspepsia and all manners of digestive issues, and pain management.

If you have a high quality (see below) oil, completely unadulterated, you will find Fennel is great for the following uses:

1. Halitosis -- Those Fennel seeds at the Indian restaurant are there for a reason. The main cause of halitosis is rooted deep in the stomach. 2 drops of Sweet Fennel essential oil in 6 ounces of water can be gargled to relieve bad breath. You might also try using a fennel toothpaste (such as Tom's of Maine).

2. Infant Colic -- Clinical in vivo studies have proven Fennel to be effective in relieving colic in infants. Do not use Fennel essential oil, however, as it is too strong for babies and toddlers. Instead, you can steep a tablespoon of Fennel seeds in two cups of hot water; use this as a tea, mix a tablespoon of it with olive oil and use as a rub on the stomach, or mix with some milk. (As a side note, if you are having problems with infant colic, the best method is a tablespoon of Fennel seeds and a tea bag of Chamomile in 2 cups of boiling water; steep for 10 minutes; strain and bring down to a temperature appropriate for an infant; add the mixture to a bath and gently massage the baby's stomach in a clockwise motion.)

3. Constipation, gas, indigestion -- Eat too much or eat the wrong thing? Fennel was made for this type of ailment. 2 drops of Fennel essential oil in 2 tablespoons of carrier oil (olive, sweet almond, jojoba, etc.) makes a great stomach rub. This blend makes enough for several doses, so rub some on in a clockwise motion. You can also make the tea mentioned above: one tablespoon of Fennel seeds and one Chamomile tea bag to 2 cups of boiling water; drink slowly. A much stronger tea uses 1 drop of Fennel essential oil and 2 drops of Lemon essential oil (Citrus Limonum) or the juice from 1/4 lemon in a cup of boiling water; drink slowly. Please note that Fennel is a laxative, so its use is contraindicated if you are experiencing diarrhea.

4. Asthma, difficulty breathing, bronchial congestion -- Boiling up 2 cups of water and adding 2 drops of Fennel essential oil, 5 drops of Peppermint essential oil (Mentha Piperita), and 5 drops of Eucalyptus essential oil (Eucalyptus Globulus or Eucalyptus Smithii) makes a soothing inhalant that will open up lung passages. Lean over a bowl of the steaming mixture and put a towel over you and the bowl to increase the intensity; make sure to close your eyes, as the Peppermint and Eucalyptus can sting!

5. Joint pain -- 2 drops in 2 tablespoons of carrier oil can be used to ease the pain of rheumatism or sports injuries. It is believed Fennel's anethole content is responsible for its anti-inflammatory quality.

I like to provide clinical data to accompany the anecdotal evidence, but there is very little out there. This is true of most essential oils; clinical trials cost money, and there isn't an aromatherapy lobby with bags of money to encourage universities and the FDA to conduct research. This is not conspiracy, it is simple fact. It is important to point out, however, that people all over the world have been using herbs and oils to treat maladies for thousands of years without the benefit of clinical studies. If these remedies didn't work, disparate cultures over millennia would have stopped using them long ago. That said, these are some of the more interesting studies on Fennel essential oil:

Alternative Therapies in Health and Medicine published the results of a study conducted by Alexandrovich, Rakovitskaya, Kolmo, Sidrova and Shusunov at the Department of Pediatrics in the St. Petersburg Medical Academy of Postdoctora Education showing "significant improvement" in the symptoms of infantile colic in the group using Fennel seed oil emulsion as compared to the placebo group. An added benefit? No side effects observed.

Two studies(1)(2) in the past few years showed Fennel essential oil to be effective against six Bacillus species, as well as E. Coli, 27 phytopathogenic bacterial species and two mycopathogenic bacterial species (phytopathogenic bacteria cause illness in plants; mycopathogenic bacteria cause disease in mushrooms). Mostly these studies were conducted to prove (or disprove) Fennel's usefulness in preserving food and/or crops, but Fennel essential oil's antibacterial activity can be one of the reasons it works so well in the digestive tract, especially against E. Coli.

An in vivo study of 60 women concluded "the essence of fennel can be used as a safe and effective herbal drug for primary dysmenorrhea, however, it may have a lower potency than [the commonly prescribed drug for dysmenorrhea] in the dosages used for this study."(3) What does this mean, and why isn't fennel listed as a treatment for dysmenorrhea on this blog? It means Fennel essential oil (possibly used in conjunction with other oils, such as Clary Sage and Geranium) can help women who experience painful menstrual cramps and irregular cycles. Fennel is not listed on this blog as a solution for this problem, because Fennel is contraindicated for women who suffer from endometriosis and estrogen-dependant cancers; dysmenorrhea can be a side effect of both endometriosis and estrogen-dependant cancers, and it is strongly recommended you eliminate all serious causes of menstrual cramps before treating yourself with essential oils. In other words, please visit your integrative physician, naturopath or midwife first!

Why does it work?

The main chemical components of Fennel essential oil are estragole and anethole, fenchone (in varying amounts, depending on the variety of Fennel), anise aldehyde and the common monoterpenes phellandrene, limonene, myrcene and pinene. (There are other chemicals present.)

When researching a quality Fennel oil, please find out the chemical breakdown from your supplier (this is why buying oils at the supermarket is a bad idea): you want an oil that is high in estragole (60% or higher) and contains less than 5% fenchone (due to possible toxicity issues, although fenchone, as noted, is excellent as an expectorant). Resist the temptation to purchase an inexpensive oil, as the "cheap" brands are often diluted with synthetic anethole. Anything synthetic or animal-derived is inappropriate for therapeutic use.

Fenchone, phellandrene, and pinene can all cause skin irritation, so please always test one drop in the crook of your arm. If you have any rashes or burning, rinse off with milk or olive oil, followed with soap and water. It is highly advisable not to use Fennel essential oil undiluted (neat). In fact, you need only 2 drops for a whole bath.

What are the dangers?

Non-organic oils, oils made poorly, oils of the wrong chemical ratios; as mentioned, you want an oil high in estragole, but very low in fenchone. You also need to be very careful of synthetic anethole as a diluent. Organic Sweet Fennel essential oil (Foeniculum Vulgare var. Dulce) from a quality supplier with the correct percentages of chemical constituents is a must for clinical application.

Fennel can cause muscle spasms and is not to be used on anyone suffering from epilepsy or nervous system disorders.

Due to the possible presence of phytoestrogens in Fennel essential oil (this is debatable), do not use Fennel if there is evidence or a history of endometriosis, estrogen-related disorders, or estrogen dependant cancers. It is the possible presence of these phytoestrogens that explains Fennel's long history as the herb for women experiencing dysmenorrhea and amenorrhea. If you suffer from painful menstrual cycles or no menstrual period at all, consult your integrative physician, midwife or naturopath first (before you try to treat yourself), as these issues can be symptoms of something more serious.

Anethole is a possible anticoagulant, so it is not advisable to use Fennel essential oil if you have problems with blood clotting or if you are on anticoagulant medications.

Always test new oils (one drop diluted in 1 teaspoon of carrier oil) on the crook of your arm for sensitization.

Don't expose yourself or anyone to any more than 5 drops (topically or inhaled) in one day (don't use anymore than 2-3 drops at any single time, and don't use for more than 3 weeks), and don't use on children under 15, pregnant moms, the very elderly or frail, cats or dogs. That said, Fennel has long been used when new mothers have trouble producing milk. Discuss this with your midwife or doctor before using, due to the fenchone content. As with all oils, err on the side of caution, i.e., if deciding between using 2 and 3 drops, use 2. With essential oils, less is always more!

Final Note.

Fennel essential oil's three main constituents -- anethole, estragole, and fenchone -- are interesting, both for their therapeutic abilities and their possible dangers. Estragole is a weak procarcinogen (meaning it needs metabolic activation to become carcinogenic)(4), but anethole has been shown to block carcinogenesis.(5) Likewise, anethole can cause liver damage at certain levels, yet the liver produces enzymes that neutralize anethole. This gives new dimension to the claims that crop up stating essential oils to be hazardous or carcinogenic.

Fenchone adds another layer to this discussion. Ketones are generally regarded as toxic even at low levels, yet there are no studies proving Fennel essential oil, used correctly and at the correct dosage, is toxic. And even if fenchone were shown to be a toxic constituent, would it be toxic if isolated from the oil or as part of the whole oil? Further, fenchone is a powerful healing constituent in terms of clearing up lung congestion.

Essential oils, like their synthetic pharmaceutical counterparts, are powerful drugs. They allow us to heal ourselves, but it is important to respect their power to damage if used improperly. In the realm of the pharmacist, apothecary and aromatherapist, there is no "good" and "bad" when it comes to oils. Each person is a unique individual, and so each treatment must be chosen according to individual needs and individual risk assessment.

As always, I urge you to consult an expert before treating yourself.

I wish you good health.



(1) Journal of Medicinal Food, Fall 2006, 9(3): 418-21, "Inhibitory effects of spice essential oils on the growth of Bacillus species," Ozcan, Sagdic, Ozkan, Department of Food Engineering, Selcuk University, Turkey. PMID 17004909

(2) Journal of Agricultural and Food Chemistry, December 29 2004, 52(26): 7862-6, "Antibacterial activity of Coriandrum sativum L. and Foeniculum vulgare Miller Var. vulgare (Miller) essential oils," Lo Cantore, Iacobellis, De marco, Capasso, Senatore, Departimento di Biologia, Universita degli Studi della Basilicata, Italy. PMID 15612768

(3) International Journal of Gynaecology and Obstetrics, February 2003, 80(2): 153-7, Namavara Jahromi, Tartifizadeh, Khabnadideh, Department of Obstetrics and Gynecology, Shiraz University of Medical Sciences, Iran. PMID 12566188

(4) Natural Standard

(5) Oncogene, June 8, 2000, 19(25):2943-50. PubMed ID 10871845