Fennel / Foeniculum vulgare

The Basics

What is Fennel / Foeniculum vulgare?

Fennel oil is commonly used to treat disorders of the digestive system.

Brand names for Fennel / Foeniculum vulgare

N/A

How Fennel / Foeniculum vulgare is classified

Complementary Therapies, Galactogogues, Phytotherapy, Plants, Medicinal

Fennel / Foeniculum vulgare During Pregnancy

Fennel / Foeniculum vulgare pregnancy category

Category N/ANote that the FDA has deprecated the use of pregnancy categories, so for some medications, this information isn’t available. We still think it’s useful to list historical info, however, given what a common proxy this has been in the past.

What we know about taking Fennel / Foeniculum vulgare while pregnant

N/A

Taking Fennel / Foeniculum vulgare While Breastfeeding

What are recommendations for lactation if you're taking Fennel / Foeniculum vulgare?

Fennel (Foeniculum vulgare) seeds contain the volatile oil composed largely of anethole, which is a phytoestrogen, as well as fenchone, estragole, 1,8-cineole (eucalyptol), and other constituents. Fennel is a purported galactogogue and is included in some proprietary mixtures promoted to increase milk supply.[1][2][3][4][5][6][7][8][9][10][11] Two small studies found an increase in some parameters such as milk volume, fat content and infant weight gain with fennel galactogogue therapy. Galactogogues should never replace evaluation and counseling on modifiable factors that affect milk production.[12] Immersing the breast in a warm infusion of fennel seeds and marshmallow root has been suggested as a treatment for breast inflammation,[13] but no scientific data are available that support this use. Anethole is excreted in breastmilk.[14] Fennel is generally well tolerated in adults, and fennel oil is generally recognized as safe (GRAS) for use in food by the U.S. Food and Drug Administration. It has been safely and effectively used alone and with other herbs in infants for the treatment of colic,[15][16][17] so the smaller amounts in breastmilk are likely not to be harmful with usual maternal doses. Some sources recommend limiting the duration of treatment to 2 weeks. Excessive maternal use of an herbal tea containing fennel, anise and other herbs appeared to cause toxicity in 2 breastfed newborns that was consistent with toxicity caused by anethole, which is found in fennel and anise. Fennel can cause allergic reactions after oral or topical use affecting the respiratory system or skin, including photosensitivity. Diarrhea and hepatomegaly occurred in a woman taking fennel, fenugreek, and goat’s rue as galactagogues.[18] Elevated liver enzymes occurred in another woman taking Mother’s Milk Tea, which contains fennel.[19] Avoid excessive sunlight or ultraviolet light exposure while using this herbal. Fennel should be avoided by mothers if they or their infants are allergic to carrots, celery, or other plants in the Apiaceae family because of possible cross-allergenicity. Dietary supplements do not require extensive pre-marketing approval from the U.S. Food and Drug Administration. Manufacturers are responsible to ensure the safety, but do not need to prove the safety and effectiveness of dietary supplements before they are marketed. Dietary supplements may contain multiple ingredients, and differences are often found between labeled and actual ingredients or their amounts. A manufacturer may contract with an independent organization to verify the quality of a product or its ingredients, but that does not certify the safety or effectiveness of a product. Because of the above issues, clinical testing results on one product may not be applicable to other products.

Maternal / infant drug levels

Fennel (Foeniculum vulgare) seeds contain the volatile oil composed largely of anethole, which is a phytoestrogen, as well as fenchone, estragole, 1,8-cineole (eucalyptol), and other constituents. Fennel is a purported galactogogue and is included in some proprietary mixtures promoted to increase milk supply.[1][2][3][4][5][6][7][8][9][10][11] Two small studies found an increase in some parameters such as milk volume, fat content and infant weight gain with fennel galactogogue therapy. Galactogogues should never replace evaluation and counseling on modifiable factors that affect milk production.[12] Immersing the breast in a warm infusion of fennel seeds and marshmallow root has been suggested as a treatment for breast inflammation,[13] but no scientific data are available that support this use. Anethole is excreted in breastmilk.[14] Fennel is generally well tolerated in adults, and fennel oil is generally recognized as safe (GRAS) for use in food by the U.S. Food and Drug Administration. It has been safely and effectively used alone and with other herbs in infants for the treatment of colic,[15][16][17] so the smaller amounts in breastmilk are likely not to be harmful with usual maternal doses. Some sources recommend limiting the duration of treatment to 2 weeks. Excessive maternal use of an herbal tea containing fennel, anise and other herbs appeared to cause toxicity in 2 breastfed newborns that was consistent with toxicity caused by anethole, which is found in fennel and anise. Fennel can cause allergic reactions after oral or topical use affecting the respiratory system or skin, including photosensitivity. Diarrhea and hepatomegaly occurred in a woman taking fennel, fenugreek, and goat’s rue as galactagogues.[18] Elevated liver enzymes occurred in another woman taking Mother’s Milk Tea, which contains fennel.[19] Avoid excessive sunlight or ultraviolet light exposure while using this herbal. Fennel should be avoided by mothers if they or their infants are allergic to carrots, celery, or other plants in the Apiaceae family because of possible cross-allergenicity. Dietary supplements do not require extensive pre-marketing approval from the U.S. Food and Drug Administration. Manufacturers are responsible to ensure the safety, but do not need to prove the safety and effectiveness of dietary supplements before they are marketed. Dietary supplements may contain multiple ingredients, and differences are often found between labeled and actual ingredients or their amounts. A manufacturer may contract with an independent organization to verify the quality of a product or its ingredients, but that does not certify the safety or effectiveness of a product. Because of the above issues, clinical testing results on one product may not be applicable to other products.

Possible effects of Fennel / Foeniculum vulgare on milk supply

Possible Effects on Lactation: A group of 5 nursing mothers were given no herb for 5 days, 15 mL of a 5 % infusion of fennel seeds 3 times daily for 10 days, followed by another 5-day control period from days 15 to 20. Their diet and environment were kept constant during the study period. Milk volume was measured daily and milk fat percentage was measured on days 5, 10, 15 and 20. Milk volume and fat content increased somewhat during the 10-day treatment period and carried over for 3 to 5 days after discontinuation.[26] Because of the lack of randomization, blinding and controls, and small number of participants, no valid conclusion can be made from this study on the galactogogue effects of fennel.

One hundred fifty-eight mothers in Iran of who reported difficulty in breastfeeding were given either a proprietary mixture of herbs (Shirafza Drop) or a chlorophyll solution as a placebo. The herbal mixture contained the purported galactogogues fennel, anise, cumin, black seed, and parsley. Infant ages ranged between 0 and 6 months and they were exclusively breastfed. Weight gain of the infants was measured over time. No difference in infant weight gain was seen between the two groups of infants.[27] Blinding and randomization in this study is unclear.

Sixty-six postpartum mothers (22 in each of 3 groups) with no concurrent illnesses were randomly assigned to receive an herbal tea, placebo, or nothing after delivering healthy, fullterm infants. Mothers in the herbal tea group received at least 3 cups daily of 200 mL of Still Tea (Humana-Istanbul, Turkey; containing hibiscus 2.6 grams, fennel extract 200 mg, fennel oil 20 mg, rooibos 200 mg, verbena [vervain] 200 mg, raspberry leaves 200 mg, fenugreek 100 mg, goat’s rue 100 mg, and, vitamin C 500 mg per 100 grams, per manufacturer’s web site November 2011). A similar-looking apple tea was used as the placebo. All women were followed by the same nurse and pediatrician who were blinded to what treatment the mothers received. Mothers who received the Still Tea produced more breastmilk with an electric breast pump on the third day postpartum than mothers in the other groups. The infants in the Still Tea group had a lower maximum weight loss, and they regained their birth weights sooner than those in the placebo or no treatment arms. No long-term outcome data were collected. Because many of the ingredients in Still Tea are purported galactogogues, including fennel, no single ingredient can be considered solely responsible for the tea’s effects, although the authors attributed the action to fengreek[28]

An herbal tea containing fennel, fenugreek, hibiscus, rooibos, vervain, raspberry, goat’s rue, and vitamin C (Humana Still-Tee, Humana GmbH, Herford, Germany) or water was randomly given to nursing mothers in a dosage of 3 cups daily beginning on the day of delivery. Several markers of antioxidant capacity were measured in breastmilk on day 1 and again after 7 to 10 days. No difference was found in the markers between mothers who received the tea and the water.[29]

An uncontrolled, nonrandomized, nonblinded study in Iran enrolled 46 healthy nursing mothers between 18 and 35 years of age. At the start of the study, mothers were all nursing their infants and having no difficulty in doing so. The mothers’ serum prolactin was measured in the morning before breakfast at least one hour after the previous nursing bout. Prolactin was measured before and after receiving powdered fennel in a dose of 3 grams daily by mouth for 15 days. The average baseline serum prolactin concentration was 64.6 mcg/L. The serum prolactin concentration after fennel therapy was 95.6 mcg/L. The difference was statistically significant. No measurements of milk production were made.[30]

A double-blind study compared the effects of an herbal tea containing 7.5 grams fennel seed powder plus 3 grams of black tea to 3 grams of black tea alone taken three times a day in mothers exclusively nursing their 0- to 4-month old female infants. After 4 weeks, breastmilk sufficiency and infant’s growth parameters were compared in the two groups. Infants whose mothers received the fennel had greater increases in the frequency of feedings, number of wet diapers, frequency of defecation, weight gain, and a slightly greater increase in head circumference than infants in the control group. No difference was seen in height gain.[31]

In a survey of 188 nursing women from 27 states (52% from Louisana), 29 had used fennel as a galactogogue. Of those who used it, 59% were not sure that it increased their milk supply and 6 reported (unspecified) side effects.[32]

A randomized trial assigned mothers of preterm infants to receive either a purported herbal galactogogue tea twice daily, a fruit tea twice daily or nothing. The galactogogue tea mixture (Natal, Hipp [Turkey]) contained 1% stinging nettle as well as melissa, caraway, anise, fennel, goat’s rue, and lemon grass in unspecified amounts. All mothers received similar breastfeeding advice from the same nurse and two groups were told that the tea would increase milk production, but compliance with the study teas was not assessed. Mother used breast pumps to extract and measure their milk and output on day 1 and day 7 of the study were compared. Although the increase in volume of extracted milk was greater in the galactogogue tea group, there was no difference in maternal serum prolactin between the groups at 7 days. No difference in infant weight gain was seen between groups, although the authors stated that additional supplementation was provided to all infants in addition to the pumped milk.[33] The study was not blinded, the randomization method was not stated, intent-to-treat analysis was not performed, and some of the numerical results were internally inconsistent, so the quality of the study was poor.

Possible alternatives to Fennel / Foeniculum vulgare

None listed