Black Cohosh for Hot Flashes: Miracle Herb or Hogwash... Hard to Know

Toni Hurst Health Guide
  • Does black cohosh work? Most women who are approaching menopause or who are in it have heard friends talk about black cohosh, an herbal treatment that many women swear helps alleviate hot flashes.


    But just like most herbal treatments and many FDA-approved drugs, it is controversial. A small but influential study on black cohosh and its effect on menopause symptoms was presented at a scientific conference in 2002. The clinical trial showed that black cohosh was effective in controlling menopausal symptoms. In a double-blind study** comparing the phytoestrogen black cohosh to placebo and to conjugated equine estrogen (such as Premarin), it had favorable estrogenic effects on bone and lipids but no effect on the uterus.

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    "Extracts of the rhizome of black cohosh (Cimicifuga racemosa) are traditionally used to treat climacteric complaints," wrote Wolfgang Wuttke and colleagues from the University of Goettingen in Germany. I assume that's science-speak for hot flashes. The author went on to write: "Little is known whether [black cohosh] preparations have effects on other than climacteric complaints such as osteoporosis and lipid metabolism."


    But here's the rub: The study was on 97 postmenopausal women. They all reported that they had more than three hot flashes per day. In double-blind fashion, the women received daily treatment for three months with commercially available black cohosh (40 mg), conjugated estrogens (0.6 mg), or placebo. By my math, if the group consisted of 97 women, and they were divided up three ways (each group got either the black cohosh, prescription estrogen or a placebo), then only about 32 women actually got the black cohosh.


    Other studies have been just as half-baked in one way or another. However, I guess enough women have been clamoring for help from hot flashes that the U.S. government started to listen back in 2000 and the National Institutes of Health (NIH) funded a study on black cohosh that even our government will stand behind (maybe).


    The black cohosh study was supposed to be completed in 2005 but the NIH says it is still in phase 2, meaning it has a ways to go. But it could be out any day, because the website that tracks these clinical trials was last updated just two days ago, June 17. As soon as that study is out, I'll try to get a copy and report on it, though it likely will make big news everywhere because menopause affects so many women.


    In the meantime, the herb gets what amounts to a pretty good endorsement from NIH in these words:


    "This herb has received more scientific attention for its possible effects on menopausal symptoms than have other botanicals. Studies of its effectiveness in reducing hot flashes have had mixed results. A study funded by National Center for Complementary and Alternative Medicine and the National Institute on Aging found that black cohosh, whether used alone or with other botanicals, failed to relieve hot flashes and night sweats in postmenopausal women or those approaching menopause. Other research suggests that black cohosh does not act like estrogen, as once was thought. Black cohosh has had a good safety record over a number of years. Some concerns have been raised about whether it may cause liver problems, but an association has not been proven."


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    When I see "mixed results" and "good safety record" coming from very conservative organizations like this, followed by a multi-million dollar study being funded right now, I'm inclined to go out and try it. I think I wouldn't try it for more that six months, and I would be sure to inform my nurse practitioner, since I am on a statin drug (to lower my cholesterol) and I know that affects the liver too. She draws blood for a "liver panel screening" every six months anyway because of the statin (Lipitor), so if something turns up wacky, I'll know soon enough. Stay tuned for more on this important study, and let the rest of us know if black cohosh works for you. 



    A double-blind study is one in which neither the subjects nor the researchers knows who belongs to the group being given the herb and who is being given the placebo, essentially a sugar pill. The researchers only find out after the study is over. That way they can't influence the subjects in any way, even with subtle cues like body language. Double-blind studies are the gold standard in scientific research.


Published On: June 19, 2008