Topic Overview

Black cohosh, also known as black snakeroot or bugbane, is a medicinal root. It is used to treat women’s hormone-related symptoms, including premenstrual syndrome (PMS), menstrual cramps, and menopausal symptoms.

Black cohosh contains potent phytochemicals that have an effect on the endocrine system. How it works is not yet clear.

Black cohosh is widely used in the United States, Australia, and Germany. The German government has approved it as a prescription alternative to hormone therapy. In the U.S., black cohosh is available without a prescription. Be sure to talk to your doctor before you take it.

You can buy black cohosh as a standardized extract in20 mg pill form (such as Remifemin), which is taken twice a day. Root, extract, and tincture forms are also available in health food stores.

When black cohosh is used at regular doses, its only known side effect is occasional stomach discomfort.^{footnote 1} But black cohosh may have risks that are not yet known, including possible effects on liver function. More research needs to be done before experts can recommend it for long-term use.

Is it effective?

Studies on black cohosh have had mixed results. Some studies have shown that black cohosh can relieve menopause symptoms such as hot flashes.^{footnote 2} But other studies have shown that black cohosh does not relieve symptoms.

These mixed results may mean that black cohosh can relieve symptoms in some women, but does not relieve symptoms in others. Or the different results may be because different preparations were used in the studies.

In the studies where black cohosh relieved symptoms, it reduced hot flashes, night sweats, and sleep problems.^{footnote 2}

Is it safe?

Large, long-term studies have not yet been done to confirm whether long-term use of black cohosh is safe. Because black cohosh has benefits somewhat like estrogen therapy, it may also have some risks like those of estrogen.

Experts do not know for sure if black cohosh causes liver problems. But they have determined that black cohosh products should be labeled with a statement of caution. Stop using black cohosh if you notice that you are weak or more tired than usual, you lose your appetite, or your skin or the whites of your eyes are yellowing. Call your doctor because these symptoms may mean you have liver damage.^{footnote 3}

If you plan to take black cohosh, talk to your doctor about how to take it safely. You may be able to take it short-term (no more than 6 months), or possibly longer but with regular checkups to look for estrogen-related changes in the uterus and breasts.

Estrogen may increase the risk of cancer in women who have a history of uterine cancer or breast cancer or who are at high risk for breast cancer. Since black cohosh may work in ways similar to estrogen, these high-risk women should avoid using black cohosh until more is known about the long-term risks.

As with any medicine, be careful to avoid overdosing with black cohosh. Symptoms of overdose include vertigo, headache, nausea, vomiting, impaired vision, and impaired circulation.

What to avoid

Black cohosh should not be used during pregnancy or while you are breastfeeding. Do not take black cohosh if there is any chance that you might be pregnant.

Black cohosh should not be combined with birth control pills, hormone therapy, or tamoxifen. It should not be used by women who are allergic to aspirin.