Fennel

Fennel is a year-round, pleasant-smelling herb with yellow flowers. Fennel is native to the Mediterranean region, but can now be found all over the world. Dried fennel seeds are often used in cooking as a spice that tastes like aniseed. However, fennel should not be confused with aniseed, even though both plants look and smell similar. The dried ripe seeds and oil of fennel are used to make medicine. Fennel is used for various digestive problems including heartburn, flatulence, a bloated feeling, loss of appetite and colic in children. Fennel is also used for upper respiratory tract infections, coughs, bronchitis, cholera, back pain, bedwetting and vision problems. Some women use fennel to increase the flow of breast milk, to promote menstruation, to ease the birth process and to increase sex drive. Fennel powder is used as a poultice for snake bites. Fennel is used as a flavoring agent in foods and drinks. In other manufacturing processes, fennel oil is used as a flavoring agent in certain laxatives and as a fragrance in soap and cosmetics.

How does fennel work?

Fennel may relax the intestines and reduce secretions in the respiratory tract.

How effective is fennel?

Fennel may be effective in treating colic in breastfed infants. A clinical study showed that breastfed infants suffering from colic who were given a specific combination product containing fennel, lemon balm and chamomile cried for less time than other infants with colic. There is not enough scientific data to make a statement about the effectiveness of fennel for stomach upset, tracheal swelling, bronchitis, cough, mild stomach and intestinal spasms, flatulence and upper respiratory tract infections. Further scientific research is needed to evaluate the effectiveness of fennel for these conditions.

Safety and side effects

Fennel is probably safe and harmless in the amounts found in food. However, there is not enough scientific data to say whether fennel is safe and harmless when used in medicinal quantities for adults or children. However, scientists have studied a combination product for colic that contains fennel, lemongrass and chamomile. This product appears to be safe and safe for infants for up to one week of use. Some people may experience allergic skin reactions to fennel. People who are allergic to celery, carrots and mugwort are more likely to be allergic to fennel. Fennel can make the skin particularly sensitive to sunlight and increase the risk of sunburn. For this reason, fair-skinned people should ensure that they use adequate sun protection when using fennel.

Precautions and warnings

Pregnancy and breastfeeding: Not enough is known about the safety of using fennel during pregnancy, so it is best for pregnant women to avoid fennel. During breastfeeding, fennel may not be safe and harmless. It has been reported that two breastfed babies suffered nervous system damage after their mothers drank an herbal tea containing fennel. Allergies to celery, carrots and mugwort: Fennel could cause allergic reactions in people who are sensitive to these plants. Hormone-sensitive diseases such as breast cancer, uterine cancer, ovarian cancer or endometriosis: Fennel could act like oestrogen. If you suffer from a disease that can be aggravated by oestrogen, you should therefore not use fennel.

Interactions

Care should be taken when combining fennel with the following medications:

Birth control pills

Some contraceptive pills contain oestrogen. Fennel may have some of the effects of oestrogen, but fennel does not have as strong an effect as the oestrogen contained in the contraceptive pill. Taking fennel in combination with the contraceptive pill could reduce the effectiveness of the contraceptive pill. For this reason, women who use the contraceptive pill and consume fennel should use an additional form of birth control.

Ciprofloxacin

Ciprofloxacin is an antibiotic. Fennel may reduce the amount of ciprofloxacin absorbed by the body. Taking fennel in combination with ciprofloxacin could reduce the effect of ciprofloxacin. To avoid this interaction, fennel should be taken at least one hour after ciprofloxacin.

Oestrogen

Large amounts of fennel may have some of the effects of estrogen, but fennel is not as potent as estrogen medications. Taking fennel in combination with oestrogen drugs could reduce the effect of these oestrogen drugs.

Tamoxifen

Some types of cancer are affected by hormones in the body. Oestrogen-sensitive cancers are cancers that are affected by the levels of oestrogen in the body. Tamoxifen is used to help treat and prevent these types of cancer. Fennel also appears to affect estrogen levels in the body. Taking fennel in combination with tamoxifen could reduce the effectiveness of tamoxifen. For this reason, fennel should be avoided when taking tamoxifen.

Dosage

The following dosages have been investigated in scientific studies:

Oral

• For colic in breastfed infants: a specific combination product containing 164 mg fennel, 97 mg lemon balm and 178 chamomile was administered twice daily for one week.

References

1. Electronic Code of Federal Regulations. Title 21, Part 182 -- Substances Generally Recognized As Safe. Available at: http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid= 786bafc6f6343634fbf79fcdca7061e1&rgn=div5&view= text&node=21:3.0.1.1.13&idno=21
2. Ostad SN, Soodi M, Shariffzadeh M, et al. The effect of fennel essential oil on uterine contraction as a model for dysmenorrhea, pharmacology and toxicology study. J Ethnopharmacol 2001;76:299-304.
3. Rosti L, Nardini A, Bettinelli ME, Rosti D. Toxic effects of a herbal tea mixture in two newborns. Acta Paediatrica 1994;83:683.
4. Savino F, Cresi F, Castagno E, et al. A randomized double-blind placebo-controlled trial of a standardized extract of Matricariae recutita, Foeniculum vulgare and Melissa officinalis (ColiMil) in the treatment of breastfed colicky infants. Phytother Res 2005;19:335-40.
5. 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;51:1391-6.