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Health Canada recently issued an advisory about a possible link between products containing black cohosh (Actaea racemosa, syn. Cimicifuga racemosa) and liver damage.1 The advisory, issued August 18, does not address the issue of black cohosh products including warnings on their labels since that is dealt with during the licensing review required of all herbal products to be sold legally in Canada. It cites 3 case reports of liver damage in Canada that may have been associated with black cohosh and follows similar advisories and warnings about black cohosh recently adopted by other countries and health agencies (see below).
In its advisory, Health Canada encourages consumers to exercise caution in the use of products containing black cohosh and to consult a healthcare practitioner with any concerns regarding its use.1 The agency further advises consumers to discontinue use of black cohosh products and consult a physician if they exhibit unusual fatigue, weakness, loss of appetite, yellowing of the skin or whites of the eyes, dark urine, or abdominal pain. The advisory stressed that case reports of liver damage are rare and that most cases have involved contributing factors that may have led to or encouraged the liver damage. According to the advisory, Health Canada is currently reviewing the safety and effectiveness of black cohosh.
Robin Marles, PhD, director of the Bureau of Clinical Trials and Health Science at the Natural Health Products Directorate of Health Canada, explained that all 3 of the Canadian cases of liver damage supposedly associated with black cohosh had serious confounding factors, including patients’ use of multiple prescription drugs in 2 of the cases and a prescription drug with alcohol use in the third. Dr. Marles said Health Canada purposefully included information in its advisory about such confounding factors and the fact that “the quality of the black cohosh products involved in these cases is not known,” which other agencies were not as careful to do. Dr. Marles believes that while any medicine may cause a very rare idiosyncratic adverse reaction, in most cases the problem is probably not due to authentic black cohosh but due to quality issues such as the identity and purity of the herbal material in products labeled as black cohosh. This is in agreement with the opinions of world experts such as Professors Norman R. Farnsworth, PhD, of the University of Illinois at Chicago (a Trustee of the American Botanical Council), Edzard Ernst, MD, of the University of Exeter, UK, and Fredi Kronenberg, PhD, of Columbia University (also an ABC Trustee) [R. Marles, e-mail to M. Blumenthal, September 8, 2006].
“It is common for some people to overreact to these cases and not see them in the light of alternatives such as hormone replacement therapy, which has a much higher rate of adverse reactions, or to compare liver toxicity of acetaminophen to black cohosh,” wrote Dr. Marles in an email to Dr. Kronenberg, a leading researcher on herbal remedies and women’s health issues and director of the Rosenthal Center for Complementary and Alternative Medicine at the Columbia University College of Physicians and Surgeons in New York (e-mail to F. Kronenberg, August 24, 2006).
“The advisory we issued is a compromise between the scientific facts and the need for regulators to take a precautionary approach to protecting the health of consumers. Hopefully the message will not cause undue alarm and our regulatory review will ensure consumers continue to have ready access to high quality black cohosh health products,” Dr. Marles added.
On July 18, the UK’s Medicines and Healthcare products Regulatory Agency (MHRA) announced that it would require warnings on the labels of all black cohosh products in the United Kingdom.2 The European Medicines Agency (EMEA) also released a press statement that day, urging patients to stop taking black cohosh if they developed signs suggestive of liver injury and encouraging healthcare professionals to ask patients about their use of black cohosh products.3 The American Botanical Council issued a Member Advisory in response to these actions, in which various herbal and pharmacological experts commented on the small quantity and poor quality of data linking black cohosh to liver hepatotoxicity and criticized the actions of these regulatory agencies.4 The first agency to require warnings on black cohosh products of potential liver damage, in February, was Australia’s Therapeutics Goods Administration (TGA). That agency claimed to have collected at least 47 adverse event reports worldwide involving a suspected association between preparations labeled as containing black cohosh and liver damage.5
--Courtney Cavaliere
References
1. Health Canada is advising consumers about a possible link between black cohosh and liver damage [advisory]. Ottawa: Health Canada; August 18, 2006. Available at: http://www.hc-sc.gc.ca/ahc-asc/media/advisories-avis/2006/2006_72_e.html. Accessed September 6, 2006.
2. MHRA action on safety concerns over black cohosh and liver injury [press release]. London: Medicines and Healthcare products Regulatory Agency; July 18, 2006. Available at: http://www.mhra.gov.uk/home/idcplg?IdcService=SS_GET_PAGE&useSecondary=true&ssDocName=CON2024116&ssTargetNodeId=389. Accessed September 6, 2006.
3. EMEA public statement on herbal medicinal products containing Cimicifugae racemosae rhizome (black cohosh, root)-serious heapatic reactions [press release]. London: European Medicines Agency; July 18, 2006. Available at: http://www.emea.eu.int/pdfs/human/hmpc/26925906en.pdf. Accessed September 6, 2006.
4. European agencies recommend liver warnings on black cohosh products [member advisory]. Austin, TX: American Botanical Council; July 20, 2006. Available at: http://www.herbalgram.org/default.asp?c=UKblackcohoshwarning. Accessed September 6, 2006.
5. Blumenthal M. Australian TGA publishes liver warning policy for black cohosh. HerbalGram. 2006;71-60-61.
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