Long-Term Side Effects of Black Cohosh

Used to treat a wide variety of gynecological disorders, including menopausal symptoms, the herb back cohosh was once used in Native American medicine. In 19th-century America, black cohosh was also used as a home remedy. Black cohosh does, however, have side effects of which to be aware, and many long-term effects aren't fully known. Understanding the potential side effects can help you determine if this product is right for you.

Identification and Uses

• Native to North America, the herb black cohosh is a member of the buttercup family. According to the National Center for Complementary and Alternative Medicine (NCCAM), black cohosh has most recently been used to treat menopausal symptoms, such as night sweats, hot flashes and vaginal dryness. Black cohosh has also been used as a treatment for menstrual difficulties and labor induction in pregnant women.

Long-Term Side Effects

• According to NCCAM, most studies on the safety and efficacy of black cohosh have lasted fewer than six months, so its long-term safety and its possible side effect aren't fully known. The American Academy of Family Physicians, however, says that there's concern for the use of black cohosh among women with a personal or family history of breast cancer. The AAFP cites a tissue-culture study that revealed that black cohosh increased the inhibitory effect of tamoxifen---a drug used to treat breast cancer---on breast cancer cell lines. Another study suggested that black cohosh was no more effective than a placebo in treating hot flashes among women with breast cancer.

Other Side Effects

• In addition to long-term side effects, black cohosh may have other side effects, such as headaches and stomach discomfort. The NCCAM says tha, in clinical trials, low numbers are side effects are reported. The AAFP says that the most reported side effect of black cohosh is gastrointestinal discomfort, and large doses can cause dizziness, headaches, nausea, giddiness and vomiting.

  The United States Pharmacopeia recommends that women who have a liver disorder should avoid black cohosh, as it may cause abdominal pain, dark urine or jaundice. Several case reports of hepatitis and liver failure have been reported by women with liver problems.

Application and Dosage Information

• The American College of Obstetrics and Gynecology doesn't recommend the use of black cohosh or other botanicals for more than six months, as many long-term effects aren't known. The American Academy of Family Physicians says most black cohosh supplements contain the extract Remifemin. Usual dosage is two 20 milligram tables twice daily. Results should be seen in four to eight weeks.

Warning

• The AAFP warns against mistaking black cohosh for blue cohosh, which is used for different reasons and does have the potential for more serious side effects.