As researchers continue evaluating botanical remedies for hot flashes, here’s what science has to say.

• Black cohosh. This herb has received more scientific attention for its possible effects on menopause-related symptoms than any other botanical. In one study testing the black cohosh supplement marketed as Remifemin, women taking a 20-mg tablet twice a day for 8 to 12 weeks reported improvement in mild hot flashes. However, a study funded by National Center for Complementary and Alternative Medicine (NCCAM) 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. Unfortunately, recently there have been several reports of liver problems in some women on black cohosh. Although this is a rare occurrence and the relationship to the herb is not proven, it bears noting.
• Soy. The scientific literature on soy for hot flashes includes both encouraging and discouraging results. Isoflavones (weak, plant-derived estrogens), most commonly found in soy foods but also in dietary supplement pills, have been found to reduce mild hot flashes by about 15% to 30% in some studies. However, other studies show no effect. Eating 1 or 2 servings of soy foods daily may provide greater benefits than supplements, but an effect on hot flashes, if any, may take weeks.
• Dong quai. Only one major study of dong quai has been done. Researchers did not find it to be useful in reducing hot flashes. Plus, dong quai is known to interact with the blood-thinning medicine warfarin. This can lead to bleeding complications in women who take this medicine.
• Ginseng. Researchers concluded that ginseng may help with some menopause-related symptoms, such as mood symptoms and sleep disturbances, and with one's overall sense of well-being. However, it has not been found helpful for hot flashes. Ginseng is also a blood thinner, so women taking anticoagulant therapy should be cautious.
• Kava. The herb kava may decrease anxiety, but there is no evidence that it decreases hot flashes. It is important to note that the Food and Drug Administration issued a warning to patients and providers about kava and Canada has banned the supplement because of its potential to damage the liver.
• Red clover. A total of 5 controlled studies found no consistent or conclusive evidence that red clover leaf extract reduces hot flashes. Some studies have raised concerns that red clover, which contains plant-derived estrogens, might have harmful effects on hormone-sensitive tissue (for example, in the breast and uterus).