A friend recently confided that she was considering taking an herbal remedy that her healthcare provider claimed would put an end to all of her menopause symptoms: hot flashes, night sweats, moodiness, exhaustion. Sound too good to be true? Unfortunately, it probably is.

The concoction my friend was considering included an herb called black cohosh. “It’s the herbal ingredient most commonly purchased to treat menopausal symptoms and it’s heavily marketed in women’s magazines, on TV and on the radio,” says menopause expert Janet S. Carpenter, Ph.D., R.N., F.A.A.N., distinguished professor and associate dean for research at Indiana University's School of Nursing.

In fact, more than half of the dietary supplements Consumer Reports found that claimed to address menopausal symptoms contained black cohosh. In 2014 consumers in the U.S. spent about $60 million on black cohosh supplements according to the Nutrition Business Journal—slightly more than they spent the previous year. But do they work and are they safe?

Here, three facts you should know about black cohosh supplements for menopause. 

There's No Proof Black Cohosh Works

“There’s really no good evidence that black cohosh makes any difference to menopausal symptoms,” says Carpenter, who was the lead author of a major menopause report published in Menopause, the journal of the North American Menopause Society in 2015. “There’s plenty of anecdotal evidence—women who say it helped them,” Carpenter says, “but overall, studies show that it's no better than a placebo.”

In particular, Carpenter cites a 2012 Cochrane review that analyzed 16 randomized controlled trials of 2,027 perimenopausal and postmenopausal women—women who were either approaching menopause or who had already gone through it. After evaluating the studies, including their design, length, frequency of side effects, and other important factors, the reviewers concluded that when it comes to reducing the frequency of hot flashes, black cohosh worked no better than a placebo.

Indeed, that placebo effect could explain why many women say black cohosh relieves their symptoms. “We know that in studies women who are given placebos consistently experience a 30 percent reduction in hot flashes,” Carpenter says. “Women report fewer hot flashes during the day while taking a placebo, and they tell us they’re waking up fewer times in a sweat during the night,” she says. 

No Guarantee That Black Cohosh Is in the Bottle

The label may say “black cohosh,” but because the Food and Drug Administration is not required to test supplement products to make sure they contain what they say they do before they reach the marketplace, there’s no good way to be sure that the black cohosh you buy is the real thing.

One potential problem: There are many varieties of cohosh, including yellow cohosh and blue cohosh, and according to the U.S. Pharmacopeia (USP), a private organization that sets standards for dietary supplements and drugs, these alternative varieties are sometimes substituted for black cohosh or added to the mix.

And even if the supplements you buy do contain black cohosh, there’s no guarantee that they contain the amount of the botanical that’s listed on the label. According to the National Institutes of Health, the composition of ingredients in dietary supplements can vary tremendously from one lot to another. A USP Verified mark indicates that the U.S. Pharmacopeia has tested samples of a product to confirm that they contain the amounts they claim on their labels, but there are no USP Verified black cohosh supplements. 

Troubling Side Effect

Researchers have linked black cohosh products to numerous incidents of liver damage. That’s why consumers should avoid using black cohosh if they have a liver disorder. The USP also advises that black cohosh supplements carry a warning statement telling consumers to discontinue use and see a doctor if they develop signs of liver trouble, such as abdominal pain, dark urine, or jaundice—a yellowing of the skin or eyes. 

Bottom line: “These products are being sold to women as if they work for hot flashes when the research shows that they don’t and there have been reports that it damages the liver,” Carpenter says. “So why are women taking it? Because it’s well marketed and women perceive themselves as having very few treatment options,” she says.

Don’t waste your money or risk your health taking black cohosh supplements no matter how convincing the ads might be.