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HALT study: Black cohosh no better than placebo for hot flashes

December 19, 2006

The results of a federally funded study to examine whether black cohosh is an effective treatment for hot flashes and night sweats - common symptoms of menopause - found that black cohosh was no better than a dummy pill.

The frequency and severity of symptoms declined by about 30 percent over 12 months regardless of whether women were taking black cohosh or placebo.

Black cohosh, a perennial herb member of the buttercup family, is the most widely used herbal remedy for hot flashes.

The Herbal Alternatives for Menopause Trial (HALT), was a one-year, double-blind, randomized, controlled trial comparing the effects of three formulations of black cohosh with hormone therapy and placebo for relief of hot flashes and night sweats.

Researchers assigned 351 women aged 45 to 55 to one of five groups:

- black cohosh alone

- multi-herb pill with black cohosh and nine other ingredients

- the multi-herb pill plus counseling to increase intake of dietary soy

- hormone therapy (estrogen with or without progestin)

- (dummy pill)

"About 80 percent of women who go through menopause experience hot flashes," said Katherine M. Newton, PhD, Associate Director for Research at Group Health in Seattle, and lead author of the study.

"Many women are looking for alternatives to hormone therapy which is the most proven remedy for hot flashes, and many are using alternative medicines," Newton said. "The most commonly used alternative is black cohosh. But we found that black cohosh was no better than placebo in treating hot flashes."

The study found that hormone therapy gave women most relief, reducing symptoms by an average of about four symptoms per day more than placebo.

Hormone therapy was included in the HALT study because it is a well-known and proven treatment to reduce menopausal symptoms. The HALT study began in 2001 and stopped the hormone therapy arm of the trial after the Women's Health Initiative found in 2002 that estrogen plus progestin increased risk for breast cancer, heart attacks, strokes and blood clots.

"Whether or not the black cohosh findings are bad news for women depends on how you look at it," said Newton. "It's disappointing that we didn't find black cohosh to be an effective remedy.

On the other hand, thousands of women, probably hundreds of thousands of women, buy products that contain black cohosh to help relieve their menopausal symptoms. Our study indicates that black cohosh is not a promising remedy to treat their hot flashes."

The HALT study was funded by the National Institute on Aging and the National Center for Complementary and Alternative Medicine. It is the most definitive study yet of the effects of black cohosh. Previous studies have been small, short-term studies that were inconclusive.

The study, "Treatment of Vasomotor Symptoms of Menopause with Black Cohosh, Multibotanicals, Soy, Hormone Therapy, or Placebo," and an accompanying editorial, " A Randomized Trial of Alternative Medicines for Vasomotor Symptoms of Menopause," is published in the Dec. 19, 2006, issue of Annals of Internal Medicine.

Editorial writers say the study is a "well-designed, adequately powered RCT that makes an important contribution, albeit one that will disappoint women who have been hoping for an effective, safe alternative to estrogen."

The good news, the editorial writers say, is that women in the placebo group experienced about a 30 percent reduction in severity and frequency of symptoms during the 12-month follow-up period.

This means that many women will probably have fewer symptoms within six to 12 months without any treatment at all.

American College of Physicians