Black cohosh supplements will be required to carry safety advice following an Australian Therapeutic Goods Administration (TGA) review, which concluded the use of the North American herb could cause liver problems in some cases.

The TGA cited 47 adverse event reports of liver reactions worldwide, including nine Australian cases, two of which required liver transplantation.

"Although some reports are confounded by multiple ingredients, by more than one medication or by other medical conditions, there is sufficient evidence of a causal association between black cohosh and serious hepatitis," the TGA said in a statement. It did, however, note that given the widespread use of black cohosh, mainly by menopausal women, "the incidence of liver reaction appears to be very low."

While existing products will be given twelve months to comply with the regulation, all newly manufactured products containing black cohosh will have to carry an advisory that states: "Warning: Black cohosh may harm the liver in some individuals. Use under the supervision of a healthcare professional."

Tony Lewis, executive director of the Complementary Healthcare Council of Australia, urged manufacturers to comply with the TGA ruling, but many herbalists and supplements makers expressed dismay at the decision, pointing to mitigating factors often overlooked in these cases, such as the use of other medicines and therapies.

"A similar situation occurred with both kava kava and vitamin A," said Marie Kendall, marketing manager at supplements manufacturer, Solgar UK. "The whole picture is not taken into account but herbs can be picked out and scapegoated." A 2004 US National Institutes of Health (NIH) workshop on the safety of black cohosh concluded that the evidence for liver toxicity risks from black cohosh "remains equivocal but certainly warrants continued monitoring." The NIH also noted, "At this time, there is no known mechanism with biological plausibility that explains any hepatotoxic activity of black cohosh."

Black cohosh has been used as a North American Indian medicine for centuries and in Europe since the early 1800s.