Black cohosh is popular as an alternative to hormonal therapy in the treatment of menopausal (climacteric) symptoms such as hot flashes, mood disturbances, diaphoresis, palpitations, and vaginal dryness. Several studies have reported black cohosh to improve menopausal symptoms for up to six months, although the current evidence is mixed.
The mechanism of action of black cohosh remains unclear and the effects on estrogen receptors or hormonal levels (if any) are not definitively known. Recent publications suggest that there may be no direct effects on estrogen receptors, although this is an area of active controversy. Safety and efficacy beyond six months have not been proven, although recent reports suggest safety of short-term use, including in women experiencing menopausal symptoms for whom estrogen replacement therapy is contraindicated. Nonetheless, caution is advisable until better-quality safety data are available. Use of black cohosh in high-risk populations (such as in women with a history of breast cancer) should be under the supervision of a licensed healthcare professional.
NB! The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.
Adults (over 18 years old)
There is no proven effective dose for black cohosh. The British Herbal Compendium recommends 40-200 milligrams of dried rhizome daily in divided doses, although traditional doses have been as high as 1-2 grams three times daily. As a tincture/liquid, the British Herbal Compendium recommends 0.4 to 2 milliliters of a (1:10) 60% ethanol tincture daily. For menopausal symptoms, studies have used 20 milligram or 40 milligram Remifemin® tablets (containing 1 or 2 milligrams of 27-deoxyactein) twice daily or 40 drops of a liquid extract for up to 12 weeks. Some clinical studies have used 20 milligrams taken twice daily. Isopropanolic black cohosh has been taken at a dose of 40 milligrams per day for 12 weeks.
Children (under 18 years old)
There is not enough scientific information to recommend black cohosh in children.
NB! There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.
Avoid if allergic to black cohosh or other members of the Ranunculaceae (buttercup or crowfoot) family. In nature, black cohosh contains small amounts of salicylic acid (which is found in aspirin), but it is not clear how much (if any) is present in commercially available products. Black cohosh should be used cautiously in people allergic to aspirin or to other salicylates.
Side Effects and Warnings
Black cohosh is generally well tolerated in recommended doses and has been studied for up to six months. High doses of black cohosh may cause frontal headache, dizziness, perspiration, or visual disturbances. Several side effects have been noted in studies including constipation, intestinal discomfort, loss of bone mass (leading to osteoporosis), irregular or slow heartbeat, low blood pressure, muscle damage, nausea, and vomiting. Dysphoria and “heaviness in the legs” may occur.
It is not clear if black cohosh is safe in individuals with hormone-sensitive conditions such as breast cancer, uterine cancer, or endometriosis. There is controversy as to whether black cohosh is similar to estrogen in its mechanism, although recent studies suggest that it may not be. The influence of black cohosh on anti-estrogen drugs (like tamoxifen) or hormone replacement therapy is not clear. It is not known if black cohosh possesses the beneficial effects that estrogen is believed to have on bone mass or the potential harmful effects such as increased risk of stroke or hormone-sensitive cancers.
A few gynecologic organ-related adverse events have been reported including vaginal bleeding and miscarriage; however, the effects of black cohosh in these events are unclear.
Hepatitis (liver damage) and liver failure has been reported with the use of black cohosh containing products. Liver transplantation has been required in some patients. These reports are concerning, although the cases have been criticized by some as not being adequately substantiated. Nonetheless, patients with liver disease should consult a licensed healthcare professional before using black cohosh.
Black cohosh should also be used cautiously in patients with a history of blood clots, seizure disorder, or high blood pressure.
Pregnancy and Breastfeeding
Safety during pregnancy and breastfeeding has not been established. Black cohosh may relax the muscular wall of the uterus and some nurse-midwives in the United States use black cohosh to stimulate labor. Black cohosh may also have hormonal effects and caution is advised during breastfeeding. There is one report of severe multi-organ damage in a child delivered with the aid of both black cohosh and blue cohosh ( Caulophyllum thalictroides ) who was not breathing at the time of birth. The child survived with permanent brain damage. However, blue cohosh is known to have effects on the heart and blood vessels and may have been responsible for these effects.
Tinctures may be ill-advised during pregnancy due to potentially high alcohol content.