Many reports of possible liver toxicity (hepatoxicity) associated with Black Cohosh have appeared over the last few years.
In an analysis of all the 69 reported cases, researchers from the Teaching Hospital of the Johann Wolfgang Goethe University of Frankfurt/Main, Hanau, Germany found that with the hepatotoxicity specific causality assessment methods, there was an excluded, unlikely, unrelated or unassessable causality for Black Cohosh (BC) in 68 of the 69 cases. One patient had a possible causality for Black Cohosh.
In general, the cases of the 69 patients were poorly documented and the confounding variables were wide ranging. The authors concluded that the analysis of the 69 cases showed little, if any, supportive evidence for a significant hepatotoxic risk of Black Cohosh.
Reference: Teschke R et al. Phytomed 2009; 16: 72-84