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Should We Add Liver Toxicity to Black Cohosh’s Résumé?
A U.S. Pharmacopeia committee rated the likelihood of black cohosh causing liver damage as "possible."
Black cohosh is a botanical product commonly used to treat menopausal symptoms, although its efficacy is unproven (JW Womens Health Feb 1 2007 and Mar 6 2008). In response to questions about whether black cohosh might be associated with liver toxicity, an Expert Committee of the U.S. Pharmacopeia (USP) analyzed 30 international adverse effects reports (AERs) of liver damage in black cohosh users.
Black cohosh formulations and doses ranged widely, from 20 mg of extract to 1500 mg of root, but all were within the recommended range. The AERs were rated with the Naranjo causality algorithm, which takes into account several perspectives: timing of substance use and adverse effect, existence of possible alternative causes, objective confirmation, and dechallenge/rechallenge (improvement of adverse effects when the substance is withdrawn and return of effects if it is reinstituted). The scoring system rates the likelihood of causation as doubtful/unlikely, possible, probable, or definitive/certain. Scores for each of the 30 AERs fell into the "possible" causation category. As a result, the USP committee recommended cautionary labeling for black cohosh products, including a statement to discontinue the product and consult a healthcare provider if the user has a liver disorder or develops symptoms of liver problems (abdominal pain, dark urine, or jaundice).
Comment: The USP directive applies only to those black cohosh products that have been submitted for the USP label, a voluntary process completed by a minority of U.S. marketers. An editorialist points out that evidence-based medicine is unlikely to answer all the questions about botanical product safety and efficacy because of the great variability among these products and their usage. Clinicians can only ask about their patients’ use of complementary and alternative interventions and remain alert to AERs. The editorialist adds, "We must also be willing to state without shame that there is much we do not know about black cohosh . . . and the treatment of vasomotor symptoms."
Published in Journal Watch Women's Health August 27, 2008
Citation(s):
Mahady GB et al. United States Pharmacopeia review of the black cohosh case reports of hepatotoxicity. Menopause 2008 Jul/Aug; 15:628.
- Medline abstract (Free)
Richardson MK. Black cohosh . . . a cautionary tale! Menopause 2008 Jul/Aug; 15:583.
- Medline abstract (Free)