Wednesday Bubble: Black cohosh – is it safe?

Posted by Liz on Jun 22, 2011 in herbal medicine | 2 comments

Back in 2009, I wrote a post regarding black cohosh (better known in scientific circles as Cimicifuga racemosa) and potential safety issues, namely harm to the liver. In it, I discussed a small case review that showed no link between ingestion of black cohosh and liver toxicity. And yet, in 2006 the European Medicines Agency and the Committee on Herbal Medicinal Products released a public statement alerting health authorities to 42 suspected liver reactions among women taking black cohosh. In the very same report, they noted how inadequately adverse reactions were documented. Indeed, only 16 of the cases were considered to have sufficient data to allow for proper assessment of a potential link, and of these, only four showed any sort of association, albeit, unproven. Regardless,  the statement resulted in Italian health authorities requesting a precautionary withdrawal of black cohosh preparations from the market, and UK authorities issuing strict label requirements and warnings.

Hence, I was intrigued when I ran across a detailed review of black cohosh safety, both from perspective of over 107 patient cases and of published study findings. Following is the lowdown:

• An Italian clinic regularly prescribed 500 mg or 1000 mg daily black cohosh, either alone or in combination with other herbs (e.g. soy isoflavones, red clover or alfalfa) for treatment of menopause symptoms and disorders (e.g. anxiety, depression, hot flashes and joint pain). None of these herbs were prescribed to women with previous cancer of the breast, ovaries, uterus or pituitary gland. Moreover, the researchers say that they had not received any reports of any sort of adverse event.
• Still, following the European health statement, they contacted 107 women in good health and in different phases of menopause, took blood samples, underwent clinical examination and participated in phone interviews to evaluate if they were still taking the herbs. Of these women, only five had chronic but benign liver disease and one, hepatitis.

The findings? Despite the four patients suffering from prior benign liver disease, there was no additional sign of liver problems nor altered laboratories indicating a worsening condition or a new condition. Nor were there any clinical signs of liver damage after a year of using high dosages of black cohosh.

The researchers who reviewed and examined patients as well as the published literature point out that the liver is central to metabolizing most drugs and hence, there is a potential for an adverse liver event from taking nearly every medication that involves liver metabolism. They note that a step-by-step examination is also necessary to rule out other causes of liver damage, including infection, alcohol use and related conditions. In so far as herbs go, they write that “it is very important before an official statement about any adverse reaction referred to an herb based product to know the brand, dose of substance assumed, type of extract [and] content of possible contaminants.” They go on to state that it is their opinion the statement could actually be used as proof that black cohosh liver toxicity is scarce because despite over a million doses used worldwide annually, there is not any fully proven case of liver toxicity. Moreover, they claim that black cohosh safety has already been established in over 3,800 participants in clinical trials.  Their conclusion? black cohosh should be considered safe, at least in so far as liver toxicity goes.

What should you do?

If you wish to try black cohosh, speak to a licensed practitioner well versed in herbal medicines. Look for a standardized form to insure that the pills contain what they say they do. And if you start feeling poorly while taking black cohosh? Stop immediately and contact the person responsible for your care.

Black cohosh and liver toxicity. This one appears to be a bubble bursting worthy.