What Are the Dangers of Fenugreek?

Fenugreek, an herbal supplement made from the seeds of the Trigonella foenum-graecum plant, has a number of traditional uses. Breastfeeding mothers use it to increase milk supply. Fenugreek has also been used as an alternative medicine for diabetes, inflammation and to induce childbirth. Like any drug, fenugreek can have side effects, some potentially serious. Do not take fenugreek as a supplement without discussing its use with your physician.

The ingredients that could cause harmful effects in fenugreek include coumarins, which can thin the blood and could cause excessive bleeding in some people. It's not known whether the dose in fenugreek is high enough to cause this effect, eMedTV states. However, people who have underlying bleeding disorders or who take blood thinning medications or anticoagulants should not take fenugreek without their doctor's approval, because increased bleeding could occur. Signs of excessive bleeding include easy bruising, vomiting blood or passing dark, tarry stools.

Because fenugreek is a uterine stimulant when taken in high doses, taking the drug during pregnancy could cause uterine contractions that might lead to preterm labor. Fenugreek has the same effect as oxytocin, a drug that induces uterine contractions in guinea pigs, according to KellyMom, the website of lactation consultant Kelly Bonyata. Using the drug as a cooking herb is safe, according to Babycentre, but supplements should not be taken at any time during pregnancy, including during labor, without your medical practitioner's approval.

Fenugreek may increase insulin output, which could lower blood glucose levels. While this might be helpful for people with diabetes, taking fenugreek in addition to anti-diabetes medicine could cause hypoglycemia, or low blood sugar levels. Hypolgycemia can cause irritation, tremors, sweating, hunger and nervousness that can lead to passing out, coma and death if not treated. If you have diabetes, ask your doctor before taking this supplement.

Fenugreek can cause stomach irritation, including diarrhea. A nursing infant who develops diarrhea could become dehydrated. Watch for signs of diarrhea or dehydration in your baby if you take fenugreek to increase milk supply. Sings of dehydration include a decrease in the number of wet diapers, loose skin or a sunken soft spot on top of the baby's head.

Fenugreek belongs to the same family as chickpeas and peanuts; an allergy to either substance could also cause an allergic reaction to fenugreek. Watch for signs of allergic reactions such as rash, shortness of breath, hives, facial swelling, difficulty breathing or collapse. Seek immediate attention if severe allergy symptoms appear.