Black Cohosh

Background

• Black cohosh, a member of the buttercup family, grows in North America. Native Americans traditionally used black cohosh for a variety of ailments and introduced it to European colonists.
• Currently, black cohosh is promoted as a dietary supplement for hot flashes and other menopausal symptoms. It’s also been promoted for other conditions, including menstrual cramps and premenstrual syndrome, and to induce labor.
• The part of the black cohosh plant used in herbal preparations is the root or rhizome (underground stem).

How Much Do We Know?

• Black cohosh has been studied for menopause symptoms in people. Most of the older studies were not of the highest quality. More recent studies have been of higher quality, but they have differed in the formulation, plant species, or dose used, so it’s difficult to know the herb’s effects with any certainty. Black cohosh has not been studied as much for conditions other than menopause.

What Have We Learned?

• Research suggests that certain black cohosh extracts and some combination products containing black cohosh may reduce some menopause symptoms. Most of the research has been on a single extract called Remifemin. Research on other black cohosh products has had inconsistent results. Guidelines released in 2015 indicate that there is a lack of consistent evidence for any benefit from black cohosh for menopause symptoms. But a 2017 review of recent research suggests that black cohosh extracts approved for treatment in Europe seem to decrease menopause symptoms.
• The research is inconsistent on whether black cohosh helps to reduce hot flashes that are related to breast cancer treatment. People with breast cancer should avoid using black cohosh before talking with their health care provider.
• There aren’t enough reliable data to show whether black cohosh is effective for other uses.

What Do We Know About Safety?

• In clinical trials, people have taken black cohosh for as long as 12 months with no serious harmful effects.
• Black cohosh can cause some mild side effects, such as stomach upset, cramping, headache, rash, a feeling of heaviness, vaginal spotting or bleeding, and weight gain.
• Some commercial black cohosh products have been found to contain the wrong herb or to contain mixtures of black cohosh and other herbs that are not listed on the label.
• Cases of liver damage—some very serious—have been reported in people taking commercial black cohosh products. These problems are rare, and it is uncertain whether black cohosh was responsible for them. Nevertheless, people with liver disorders should consult a health care provider before taking black cohosh products, and anyone who develops symptoms of liver trouble, such as abdominal swelling, dark urine, or jaundice, while taking black cohosh should stop using it and consult a health care provider.
• The risk of interactions between black cohosh and medicines appears to be small. Preliminary animal research supported by NCCIH and other laboratory research suggested that black cohosh might affect statin medicines, which are used to reduce blood cholesterol levels.
• It’s not clear if black cohosh is safe for women who have had hormone-sensitive conditions such as breast cancer.
• Little is known about whether it’s safe to use black cohosh during pregnancy or while breastfeeding.
• Black cohosh should not be confused with blue cohosh (Caulophyllum thalictroides), which has different effects and may not be safe. Black cohosh has sometimes been used with blue cohosh to stimulate labor, but this use was linked to severe adverse effects in at least one newborn.

Keep in Mind

• Take charge of your health—talk with your health care providers about any complementary health approaches you use. Together, you can make shared, well-informed decisions.

For More Information

• Using Dietary Supplements Wisely
• Know the Science: How Medications and Supplements Can Interact
• Know the Science: 9 Questions To Help You Make Sense of Health Research

Key References