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Black cohosh is a flowering plant that’s native to North America. Its scientific names are Actaea racemosa and Cimicifuga racemosa, and it’s sometimes called black bugbane, black snakeroot, baneberry, or fairy candle (1).

The popular women’s health supplement Remifemin contains black cohosh as an active ingredient.

Its flowers and roots were commonly used in traditional Native American medicine, and today it’s a popular women’s health supplement claimed to help with menopause symptoms, fertility, and hormonal balance.

It may be effective because it functions as a phytoestrogen, a plant-based compound that mimics the action of the hormone estrogen. However, there’s some debate as to whether black cohosh can be classified as a true phytoestrogen (2, 3).

Regardless, black cohosh appears to be beneficial for relieving menopause symptoms. Still, evidence for its other uses is lacking.

Black cohosh has a number of potential benefits — most of them related to women’s health or hormonal balance. Yet, with the exception of menopause symptoms, there is little evidence to support its use for any of these conditions.

Menopause and menopause symptoms

Alleviating menopause symptoms is the reason most people use black cohosh, and it’s one of the uses that has the most compelling evidence to support it.

In one study in 80 menopausal women who were experiencing hot flashes, those who supplemented with 20 mg of black cohosh daily for 8 weeks reported significantly fewer and less severe hot flashes than before they started the supplement (4).

What’s more, other human studies have confirmed similar findings. Though larger studies are needed, black cohosh appears to be beneficial for alleviating menopause symptoms (5).

Fertility

Although you may see many claims online that black cohosh can improve fertility or help you get pregnant, there’s not a great deal of evidence to support this.

However, research indicates that black cohosh may improve the effectiveness of the fertility drug Clomid (clomiphene citrate) in people who are infertile, increasing their chances of becoming pregnant (6, 7, 8).

Three small human studies show an improvement in pregnancy rates or ovulation in women with infertility who took black cohosh supplements along with Clomid (6, 7, 8).

Still, these studies were small, and more research is needed to confirm this effect.

Women’s health

Black cohosh is also used for a number of other purposes related to women’s health. However, the evidence supporting these benefits is not as strong as the evidence supporting its benefits for menopause and fertility.

Here are a few more reasons women may use black cohosh to support hormonal balance:

  • Polycystic ovarian syndrome (PCOS). Supplementing with black cohosh may increase a woman with PCOS’s chances of getting pregnant on Clomid. Supplementing with black cohosh may also help regulate your cycles if you have PCOS (8, 9).
  • Fibroids. One 3-month study in 244 postmenopausal women found that supplementing daily with 40 mg of black cohosh may decrease the size of uterine fibroids by up to 30% (10).
  • Premenstrual syndrome (PMS) and premenstrual dysphoric disorder (PMDD). Though there are some claims online that black cohosh can help with PMS or PMDD, there’s no substantial evidence to support this.
  • Menstrual cycle regulation. In women with or without PCOS who are receiving fertility treatments like Clomid, black cohosh may help regulate their menstrual cycle (6, 7, 8).

Cancer

Black cohosh has some potentially estrogenic activity, meaning it behaves like the hormone estrogen, which may worsen breast cancer or increase your breast cancer risk (11).

However, most studies show that black cohosh does not affect your breast cancer risk. In two human studies, taking black cohosh was associated with a decreased risk of breast cancer (11).

In test-tube studies, black cohosh extract exhibited anti-estrogen activity and helped slow the spread of breast cancer cells (12).

Still, more research needs to be done to understand the link between breast cancer and black cohosh.

Mental health

Black cohosh may have some beneficial effects on mental health, particularly in menopausal women.

One review of studies investigated the use of herbal supplements for anxiety and depression in menopausal women. Researchers found that supplementing with black cohosh had no effect on anxiety, but it was linked to significant improvements in psychological symptoms (13).

Yet, more research is needed before the effect of black cohosh on mental health is fully understood.

Sleep

Although there’s little evidence that black cohosh can improve sleep, it may help reduce symptoms that are causing sleep disturbances in menopausal women, such as hot flashes.

However, one small study in 42 menopausal women found that supplementing with black cohosh seemed to improve sleep duration and quality (14).

Another study noted that a combination of black cohosh and other compounds — including chasteberry, zinc, ginger, and hyaluronic acid — helped improve hot flashes that were associated with insomnia and anxiety (15).

Still, it’s hard to say whether black cohosh or one of the other ingredients was the beneficial compound in this mixture.

Weight loss

Menopausal women may be at an increased risk of unwanted weight gain, as their estrogen levels naturally decrease (16).

Theoretically, because black cohosh may exhibit estrogenic effects, it may have a small beneficial effect on weight management in menopausal women (16).

However, the evidence to support this is minimal. More and larger human studies are needed to understand the link, if any, between black cohosh and weight management.

Black cohosh has some potential side effects, but they’re typically mild. They include digestive upset, nausea, skin rashes, infection, muscle pain, breast pain or enlargement, and spotting or bleeding outside of your menstrual cycle (17).

However, black cohosh has also been linked to some severe cases of liver damage. For this reason, you shouldn’t take black cohosh if you have liver disease or are taking any other supplements or medications that may harm your liver (17).

Moreover, a recent animal study observed that black cohosh in high doses was linked to red blood cell damage, leading to anemia. Still, more research is needed to study these potential effects in humans (18).

Because black cohosh has not been extensively studied, you may experience some side effects that are not yet widely known. If you have any concerns, consult a healthcare provider.

Black cohosh is available in capsule, liquid extract, or tea form.

Dosage recommendations vary widely between black cohosh brands. Typical doses are anywhere from 20–120 mg of standardized black cohosh extract or powder daily (17).

For menopause symptoms, taking at least 20 mg of black cohosh daily — which most brands will provide — appears to be effective (4).

Some health professionals claim you should not take black cohosh for longer than 6 months to 1 year because of its slight potential to cause liver damage (17).

Because supplements are primarily subject to post-market regulation by the government, you should choose black cohosh supplements that have been third-party tested for quality. Some of these third-party testing organizations include United States Pharmacopeia (USP) and ConsumerLab.

Additionally, black cohosh is often sold in blends containing other herbal supplements, including:

  • Red clover. Black cohosh and red clover can be taken together to help manage menopause symptoms, but there’s no evidence that they’re more effective than a placebo (19).
  • Soy isoflavones. Like black cohosh, soy contains phytoestrogens that may help improve hormonal issues or menopause symptoms, but there’s little evidence to support these potential effects (20).
  • St. John’s wort. In combination with black cohosh, St. John’s wort appears to have some beneficial effects on menopause symptoms (21).
  • Chasteberry. Chasteberry and black cohosh supplements are sold for menopause symptom relief, but there’s little evidence that they’re more effective than a placebo (22).
  • Dong quai. Black cohosh and dong quai are claimed to reduce menopause symptoms and possibly induce labor in pregnant women, but there’s no evidence to support this.
  • Vitamin C. Vitamin C is recommended online alongside black cohosh to help induce miscarriage or abortion in the case of an unwanted pregnancy. However, there’s no evidence to support this use.

According to existing evidence, there do not appear to be any complications associated with stopping black cohosh suddenly, nor are there any known withdrawal symptoms.

Because black cohosh may potentially affect your hormones, you may experience changes to your menstrual cycle when you stop taking it.

If you have any concerns about stopping black cohosh, consult a healthcare provider.

It’s unknown whether it’s possible to overdose on black cohosh. To ensure your safety and minimize your risk of liver damage, take no more than the recommended daily dose of the black cohosh supplement you choose.

If you can, purchase a supplement that has been tested by a third-party organization like ConsumerLab or USP to ensure that the ingredients in the supplement align with the claims on the label.

Black cohosh has the potential to interact with other medications and therapies. Here are its known interactions:

  • Hormone replacement therapy (HRT). Black cohosh may have some effects on your hormone levels — particularly your estrogen levels — which can have unexpected effects when paired with HRT (23).
  • Birth control pills. Most birth control pills are made of estrogen and/or progesterone, so black cohosh — which may affect your hormone levels — may interfere with hormonal birth control (6, 7, 8).

Black cohosh may have additional drug interactions that have not yet been identified. If you’re taking either of the medications listed above or have any concerns about black cohosh and other medications, consult a healthcare provider before taking it.

Additionally, because one of the most severe side effects of black cohosh is liver damage, you should be cautious of taking black cohosh in combination with any other supplements or medications that may damage your liver. Consult your healthcare provider for guidance.

Black cohosh should be kept sealed and stored at room temperature. Typically, herbal supplements don’t expire until 2 years after they’re manufactured. For your safety, it’s best to use or discard the supplement by its expiration date.

In traditional Native American medicine, black cohosh was often used to increase breastmilk production (24).

However, there’s little evidence that it works for this purpose.

Black cohosh may also increase your chances of pregnancy if you’re undergoing fertility treatments, so a healthcare provider may recommend adding it to your routine if you’re struggling to get pregnant.

Although most side effects are mild, little is known about the effects of black cohosh on pregnant women, breastfeeding women, and infants.

Still, the supplement has been used to induce labor and miscarriage, and although evidence is lacking to support its use for this, some people online report success. Regardless, labor should be induced only at the direction of a qualified healthcare provider.

For these reasons, it’s best to avoid it or discontinue use when you become pregnant or if you’re breastfeeding (24).

Generally, black cohosh is safe for most people who are not pregnant or nursing.

However, there’s no need for the supplement to be given to children. Because it may affect hormone levels, it should only be given to adolescents at the direction of a qualified healthcare provider.

People with kidney disease should be cautious when using black cohosh, as little is known about the body’s ability to excrete it when the kidneys are damaged.

Additionally, given that one of the most severe potential side effects is liver damage, you should avoid black cohosh supplements if you have liver disease.

Some potential alternatives to black cohosh include blue cohosh, rhapontic rhubarb, and evening primrose oil.

Blue cohosh is not related to black cohosh, but it’s also a North American flowering plant that’s used for women’s health. However, like with black cohosh, there’s little evidence to support its use. It may also have some severe side effects (25).

Rhapontic rhubarb is used for many of the same reasons as black cohosh, and it’s the active ingredient in the popular menopause supplement Estroven. It appears to have some benefits for the treatment of menopause symptoms (26).

Finally, evening primrose oil has effects similar to those of black cohosh on hot flashes, so it may be a promising alternative (4).