In recommended doses, black cohosh is possibly safe for some people and is sometimes recommended for women suffering from menopause, notes WebMD. However, the effectiveness of black cohosh is still under research, as of 2015.
Black cohosh is unsafe for use by pregnant women and women with breast or uterine cancers or endometriosis, reports WebMD. People under 18, those who have liver disease, stroke risks or seizure disorders, and people who are allergic to aspirin should not take black cohosh. Additionally, anyone who takes sedatives, blood pressure medication, birth control pills or hormone replacement therapy drugs should consult a physician before taking black cohosh. For the treatment of menopause symptoms, standard dosing is 20 to 40 milligrams twice daily, while a dose of 900 milligrams or more constitutes an overdose. When taken, treatment should not last for longer than a year.