Black cohosh is a flowering plant. It grows in parts of the United States and Canada.

The perennial produces white flowers from June to September, but it gets its name from its black roots. The roots are believed to have healing properties.

The black cohosh root has a long history of being used to treat medical conditions. Native Americans used black cohosh in a wide variety of ways, including:

  • kidney issues
  • malaria
  • rheumatoid arthritis
  • joint inflammation
  • sore throat
  • helping with labor
  • menstrual cramps
  • menopause

Early American colonists used black cohosh to treat snake bites, uterus issues, nervous disorders, and more. Black cohosh was also an ingredient in Lydia Pinkham's Vegetable Compound, an herbal menstrual cramp remedy popular in the early 1900s.

Today, black cohosh is mainly used to help treat symptoms associated with menopause. Read on to learn more about how it’s used and the potential side effects.

How is black cohosh used?

The roots of black cohosh are dried and made into teas, liquid extracts, and put into capsule form. Sometimes, black cohosh is used as one ingredient in an herbal mixture.

Remifemin is an example. It’s a mixture that’s been sold as a menopause tablet for 40 years in Europe. It contains 20 milligrams (mg) of black cohosh extract.

You can buy supplements with black cohosh as a concentrated liquid, in pill form, or as part of an herbal combination formula. It’s available in most drug stores or online.

There’s no standardized dose for the herb. Extracts and mixtures can vary in the amount they contain. Generally, 20 to 40 mg is used to treat menopause symptoms.

What are the benefits of black cohosh?

The most widely studied treatment use of black cohosh has been for hot flashes and other menopause symptoms. But research is still mixed as to whether it’s effective or not.

Some studies say it does help reduce hot flashes and improves mood and sleep patterns for women during menopause. Other research has shown the herb to be ineffective.

Experts aren’t sure exactly how black cohosh works or why it might be helpful for menopause symptoms. One theory is that it may have estrogenic activity, though this has not panned out in studies. For this reason, it’s possible that black cohosh is harmful for women going through treatment for breast cancer, at least for estrogen-positive tumors.

What does research say about the effectiveness of black cohosh?

Studies funded by the National Center for Complementary and Integrative Health reported conflicting findings regarding the effectiveness of black cohosh used alone or in combination with other herbs in reducing hot flashes and/or night sweats. Women in the study were premenopausal or menopausal.

One recent study in the International Journal of Reproductive Biomedicine found black cohosh, along with a few other herbs used in Iranian medicine, to be an effective alternative treatment for women experiencing hot flashes.

Most of the clinical studies have focused on treating menopause symptoms. The women in the studies have only been evaluated for about six months. For this reason, the current American College of Obstetrics and Gynecology guidelines on herbs as treatment for menopause support only using black cohosh for six months or less.

What are the side effects of black cohosh?

Black cohosh is associated with generally mild side effects, though some are more serious than others. One of the major side effects is liver damage.

Don’t use black cohosh if you have a history of liver disorders. Also avoid it if you’re experiencing symptoms that can signal liver trouble, like abdominal pain, jaundice, or dark-colored urine.

Other side effects of black cohosh include:

  • upset stomach
  • dizziness
  • headache
  • nausea
  • vomiting
  • low blood pressure
  • changes in heart rhythm

The black cohosh plant is in the same family as the buttercup plant, so people who have allergies to buttercups should not try black cohosh.

Black cohosh isn’t recommended for use during pregnancy or breast-feeding. There’s a risk of causing early labor for women who are pregnant. It’s not yet known if the herb is safe for breast-feeding women. It is also not recommended for use in children.

Other considerations when using black cohosh

Herbs, vitamins, minerals, and other plant extracts are considered dietary supplements. These aren’t required to be regulated by the Food and Drug Administration (FDA). That means these products don’t have to meet standards set by the FDA the way medications and food do.

It’s possible for manufacturers to make misleading claims about the product’s effectiveness. The ingredients can also vary. In some cases, particularly with mixtures, the supplement might not contain what it claims to.

Before buying dietary supplements, check to see if the supplement maker has a large amount of negative reviews or outstanding lawsuits. Buy only from good, reputable sources.

Herbs have the potential to interact with other medications, so you should always talk to your doctor about adding supplements to your treatment plan.

Next steps

There’s some evidence that black cohosh can help treat hot flashes. But experts don’t know enough to say for sure if it will offer relief from menopausal symptoms. It’s likely a safe alternative treatment if used for six months or less.

If you’re considering trying the herb, first talk to your doctor. Taking black cohosh might help, but it’s not a substitute for any recommended treatments.