Fennel and fenugreek are herbs commonly used to flavor food. In greater amounts they can be used as herbal medicines. Fennel may help treat indigestion and stimulate milk flow in breastfeeding women, and fenugreek may help with skin conditions and loss of appetite, according to Drugs.com. When used in amounts greater than those typically found in food, however, these herbs may not be safe for everyone. Speak with your doctor before taking fennel or fenugreek supplements.
Potential Side Effects
The main side effect of fenugreek is a harmless change in your urine, making it smell like maple syrup. High amounts may also cause gas, nausea and diarrhea. Fenugreek can also cause allergic reactions, although these aren't common, according to Drugs.com. Fennel side effects include skin reactions and sun poisoning. Some young girls develop breasts earlier than usual due to the use of fennel, and fennel oil may cause seizures or hallucinations in some people.
Both fennel and fenugreek may interfere with some medications, so seek your doctor's approval before using these supplements. Because fenugreek can affect blood sugar levels and blood clotting, don't take it if you are on medications that thin your blood or lower your blood sugar; it can increase their effects. It may also increase the effects of MAOIs and decrease the effects of corticosteroids and other hormonal medications. Its high fiber content can decrease the absorption of medications, so don't take fenugreek with other medicine.
Fenugreek is generally regarded as safe for healthy adults, but there are concerns about the potential toxicity of fennel. A compound called estragole in fennel essential oil can cause tumors in animals and may increase the risk of cancer, according to Drugs.com. An article published in "Evidence-Based Complementary and Alternative Medicine" in 2012 notes that estragole is only one compound in fennel and that other compounds in fennel may decrease cancer risk, potentially counteracting any adverse effects from estragole. More research is necessary to determine whether fennel increases cancer risk.
Who Should Avoid Them
Because fennel can bring on bleeding and potentially cause a miscarriage and fenugreek can bring on contractions, pregnant women should avoid using them. Children and those with kidney or liver disease may want to avoid fenugreek as well since it isn't well-studied in these populations.