The newspapers, radio and television have all been running a story about a study on black cohosh. The impression that these stories give: women have been using black cohosh root because they think it helps with hormonal balance and menopause, but now that scientists have studied things, there is conclusive proof that the women are just placeboing themselves into feeling better. But the research that is being mindlessly reworded for hundreds of stories has serious problems with its methodology and conclusions.

My wife's response to the story was simple: "I don't believe it." She has taken black cohosh and associated it with a significant reduction in hot flashes and other hormone related symptoms. She believes the herb has a positive effect on her libido. So I looked at the research on black cohosh, and tracked down the study in the news. And one glaring problem with the new study was obvious: the dosage used to 'prove' that black cohosh has no effect was much, much smaller than most women take.

A summary of the study that kicked off the media frenzy can be found here: Treatment of Vasomotor Symptoms of Menopause with Black Cohosh, Multibotanicals, Soy, Hormone Therapy, or Placebo

This study tested two herbal options. One included 160 milligrams of black cohosh per day, and the other included 200 millgrams of cohosh plus other botanical ingredients per day. By contrast, the bottle of one common black cohosh supplement in our house contains 540 mg per capsule, and the reccomended dose is up to 3 capsules per day. Do the math, and it is clear that many women are taking ten times more cohosh root than was used in the study.

Could that make a difference? Sure. If someone tested one-half of a baby aspirin as a headache treatement and concluded that it was no more effective than placebo, would it make make sense to generalize and conclude that aspirin itself was worthless for headaches? That is what the authors of this study did when they concluded "black cohosh used in isolation, or as part of a multibotanical regime, shows little potential as an important therapy for relief of vasomotor symptoms [of menopause]. Although they may have done fantastic double-blinding, patient selection and statistical analysis, they did not give adequate thought to the dosage they chose. And they made a sweeping conclusion not supported by the facts.

A number of other studies have shown that black cohosh has mild estrogenic effects, can reduce hot flashes, and improves the thickness of vaginal mucosa in menopausal women.

Other research on black cohosh:

Efficacy and tolerability of the Black cohosh (Actaea racemosa) ethanolic extract BNO 1055 on climacteric complaints: A double-blind, placebo- and conjugated estrogens-controlled study. Black cohosh found to be equivalent to conjugated estrogen in reducing menopause hormonal symptoms.

Phase III double-blind, randomized, placebo-controlled crossover trial of black cohosh in the management of hot flashes: NCCTG Trial N01CC1. - A study that found that 20 mg per day of black cohosh root once a day is innefective. Ok, but how does 20 mg of a compound compare to 1080 mg or 1620 mg that women are taking?

Contrasting effects of estradiol, testosterone and of a black cohosh extract on density, mechanical properties and expression of several genes in the metaphysis of the tibia and on fat tissue of orchidectomized rats. Estrogen and black cohosh both improved a number of biochemical measures in rats with their ovaries removed (things like bone stability, gene expression of osteocalcin, TGFbeta1 and tartrate-resistant acid phosphatase, orx-induced fat accumulation and leptin concentrations.) Sure, it's a lab experiment on rats, but orchidectomized rats are accepted as a generally good model for measuring the effects of drugs on hormone metabolism.

Effects of black cohosh (Cimicifuga racemosa) on bone turnover, vaginal mucosa, and various blood parameters in postmenopausal women: a double-blind, placebo-controlled, and conjugated estrogens-controlled study. These results suggest that CR has beneficial effects on bone remodeling and improves vaginal mucosa.



Several studies that show that black cohosh blocks or slows the development of some types of breast cancers. It's too soon to recommend the root as a treatment for a life-threatening disease like breast cancer. But the root of Cimifuga racemosa rises above the sugar pills when it comes to influencing hormones.


Black Cohosh is usually thought of as a women's herb, but there's also plenty of research showing that black cohosh may help men as well. Like the drug Finasteride, cohosh contains a potent alpha-5-reductase inhibitor that blocks the conversion of testosterone into dihydrotestosterone(DHT). DHT has been identified as a risk factor for prostate cancer, some heart disease, and male pattern baldness. Maybe someday guys will be taking this root, or a derrivative from it to help them cope with mannopause?



Many women have reported prosexual effects when taking black cohosh. It is not clear if this is simply from normalizing the sex hormones and restoring balance and sexual energy, or whether there is a direct aphrodisiac effect.

Health Concerns

There have been a small number of cases of liver injury that some researchers believe are linked to black cohosh. European agencies are talking about banning this herb.

This is definitely an area that needs watching. It's possible that the herb was the cause in these cases, although there are so few cases that it isn't possible to get an accurate picture of the risk at this time.

In comparison, the over-the-counter painkiller acetominophen (found in Tylenol, Paracetamol, Panadol and many other products) is estimated to cause hundreds of thousands of cases of liver damage each year. This problem is most common in people that take a large dose and have low levels of the antioxidant glutathione. But even healthy people have been known to suffer liver failure from a single dose of acetominophen. Does that mean that all acetominophen should be banned, or that the product should be by prescription only? I don't think so.

I think the rational attitude is to realize that nothing is a zero-risk activity. Society accepts the fact that acetominophen may cause some problems, but also acknowledges that it is useful for lowering fever, reducing swelling, and treating pain. It is an option for people that want it, and it would be wrong to panic and ban it. The same is true for black cohosh.

A woman's decision to take black cohosh or hormone replacement therapy (or any other treatment for menopause) is ultimately tied to statistics and to personal comfort with a particular choice. Does any one know how black cohosh compares to hormone replacement therapy in terms of the odds-ratio of having liver problems? Not at this time. But that doesn't stop some 'experts' from trying to scare women away from black cohosh, and it seems that most of those experts are comfortable with hormone replacement.

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