Studies confirm that black cohosh is effective for relieving menopausal symptoms. Early German studies found black cohosh improved physical and psychological menopausal symptoms, including anxiety, hot flashes, night sweats, and vaginal dryness. More recently, studies have linked black cohosh to reduced sleep disturbance among menopausal women.
Some studies suggest black cohosh can help ease premenstrual syndrome (PMS) and menstrual pain.
Breast cancer medications such as tamoxifen (Nolvadex) can cause hot flashes. While many breast cancer patients may take black cohosh to reduce the number and intensity of hot flashes, two well-designed studies concluded that the herb is no more effective than placebo.
Preliminary studies suggest that black cohosh may help reduce inflammation associated osteoarthritis and rheumatoid arthritis. In a review of scientific studies, researchers concluded that a combination of black cohosh, willow bark (Salix spp.), sarsaparilla (Smilax spp.), guaiacum (Guaiacum officinale) resin, and poplar bark (Populus tremuloides) may help relieve symptoms of osteoarthritis. However, there is not enough human research to support the use of black cohosh alone for arthritis.
Laboratory studies have found that plant-based estrogens (called phytoestrogens) in black cohosh may inhibit bone loss, such as seen with osteoporosis. More research is needed.