Black Cohosh: Benefits, Dosage, and Safety

What black cohosh is

Black cohosh (Actaea racemosa, also called Cimicifuga racemosa) is a perennial plant in the buttercup family, native to North America. Supplements are made from its roots and rhizomes (underground stems). It is a botanical dietary supplement, not an essential nutrient, so it has no dietary requirement. It is most commonly used in an attempt to ease menopausal symptoms such as hot flashes and night sweats.

What it does

• Marketed for relief of menopausal vasomotor symptoms such as hot flashes and night sweats, though ODS reports the evidence is insufficient
• Its active ingredients and mechanism of action are unknown; it is not an essential nutrient and has no established role in normal human physiology
• Proposed but unproven mechanisms include modulation of serotonergic pathways and possible antioxidant, anti-inflammatory, or selective estrogen receptor modulator activity

Intake and dosing

Black Cohosh is not an essential nutrient, so no Recommended Dietary Allowance or Tolerable Upper Intake Level has been set. Doses in studies vary widely. Because supplement doses are not standardised, discuss an appropriate amount with a clinician or pharmacist.

Deficiency and who is at risk

Not applicable. Black cohosh is an herb, not an essential nutrient, so there is no deficiency state or dietary requirement.

Who may need more

• Postmenopausal and perimenopausal women who use it to try to reduce hot flashes and night sweats (note: ODS reports evidence is insufficient to support this use)
• No one requires black cohosh nutritionally; it is not an essential nutrient

Food sources

Not a dietary nutrient and not obtained from foods. Black cohosh comes only from the root and rhizome of the Actaea racemosa (Cimicifuga racemosa) plant, taken as an herbal supplement.

Forms and absorption

Sold as dietary supplements made from root and rhizome, in forms including powdered whole herb, liquid extracts, and dried extracts in pill form. Preparations vary considerably in chemical composition because the active compounds are not known. Products are frequently standardized to provide at least 1 mg triterpene glycosides per daily dose. Remifemin, a commercial extract used in several studies, is standardized to be equivalent to 40 mg black cohosh root/rhizome (isopropyl-alcohol extracted) per daily dose of two tablets, but is not standardized to triterpene glycoside content. Doses in trials ranged from 6.5 to 160 mg/day, with a median of 40 mg/day.

Safety, excess and interactions

Too much

No Tolerable Upper Intake Level is established. In clinical trials the most common side effects were mild, transient gastrointestinal upset and rashes; other reported effects included breast pain or enlargement, infection, vaginal bleeding or spotting, and musculoskeletal complaints, at rates similar to placebo. Worldwide there have been at least 83 reported cases of liver damage (hepatitis, liver failure, elevated liver enzymes, and other liver injuries) associated with black cohosh use, though no causal relationship has been established and some cases may reflect impurities, adulterants, or wrong Actaea species. Long-term safety beyond about 6 months has not been studied.

Interactions to know

• Black cohosh is not known to have any clinically relevant interactions with medications, although this has not been systematically studied (per NIH ODS).

How status is measured

Not routinely measured. There is no laboratory marker of black cohosh status because it is not an essential nutrient. Because of hepatotoxicity reports, clinicians may monitor liver function (liver enzymes) if a user develops symptoms of liver trouble such as abdominal pain, dark urine, or jaundice.

Regulated as a dietary supplement in the United States, not as a drug, so it is not FDA-approved for treating any condition. The U.S. Pharmacopeia recommended a cautionary liver-warning label in 2008, but the FDA does not require such a warning on black cohosh product labels. Australia requires a liver-harm warning statement on products containing black cohosh.

What the evidence supports

We grade the strength of evidence behind each common reason people take black cohosh, mirroring how the NIH describes it.