There is no difference between black cohosh and cohosh. Both terms refer to extracts made from the root and rhizomes, or underground stems, of Cimicifuga racemosa, also known as Actaea recemosa, which is a member of the buttercup family. The plant is avoided by insects, which may have contributed to some of the common names for black cohosh, namely rattleroot, rattletop, rattleweed, bugbane and bugwort.
Historical Uses
According to the Office of Dietary Supplements of the National Institutes of Health, Native Americans used cohosh for "malaise, gynecological disorders, kidney disorders, malaria, rheumatism, and sore throat." It was also used to treat colds, coughs, hives, backache, constipation, hives and the inducement of lactation. Nineteenth-century American uses were for rheumatism and fever, as a diuretic, and to induce menstruation.
Commercially Available Formulations
Remifemin, a tablet formulation containing black cohosh extract equivalent to 20 mg of root, is one of the better-known formulations of cohosh, and is generally the formulation used in clinical trials of its effectiveness in various potential uses. Remifemin had also been available as an elixir containing 60-percent-by-volume ethanol. Comparisons of studies using the two formulations are problematic.
Current Authority on Black Cohosh
According to the Office of Dietary Supplements, "Black cohosh is used for hot flashes and other menopausal symptoms. ... Although preliminary evidence is encouraging, the currently available data are not sufficient to support a recommendation on the use of black cohosh for menopausal symptoms." Interestingly enough, the American College of Obstetricians and Gynecologists has stated that black cohosh may be helpful for women with vasomotor symptoms, or hot flashes, of menopause in the short term--fewer than six months.
Mechanism of Action
According to the Office of Dietary Supplements, how black cohosh works is not known. There is some evidence that black cohosh exhibits estrogen-like activity, but the evidence is mixed, and studies that have looked specifically at changes in hormone levels before and during use of black cohosh have failed to find any significant changes. Another theory is that it exhibits serotonin-like effects on the brain.
Regulatory Status and Side Effects
Black cohosh is sold as a dietary supplement and is subject to regulation as a food rather than a drug. As a result, the concentration and purity of the material cannot be guaranteed. Reported side effects of black cohosh are stomach upset, weight gain and headaches. One woman developed acute hepatitis and required a liver transplant. Although no other cause of liver disease was found, this is not proof that black cohosh causes liver damage.
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