Side Effects and Cautions

• Black cohosh can cause headaches and stomach discomfort. In clinical trials comparing the effects of the herb and those of estrogens, a low number of side effects were reported, such as headaches, gastric complaints, heaviness in the legs, and weight problems.
• No interactions have been reported between black cohosh and prescription medicines.
• Black cohosh has recently been linked to a few cases of hepatitis (inflammation of the liver), but it is not clear whether black cohosh caused the problem.
• It is not clear if black cohosh is safe for women who have had breast cancer or for pregnant women.
• Black cohosh should not be confused with blue cohosh (Caulophyllum thalictroides), which has different properties, treatment uses, and side effects than black cohosh. Black cohosh is sometimes used with blue cohosh to stimulate labor, but this therapy has caused adverse effects in newborns, which appear to be due to blue cohosh.
• It is important to inform your health care providers about any herb or dietary supplement you are using, including black cohosh. This helps to ensure safe and coordinated care.