Antidepressants are hitting the market with a flurry -- and not just to perk up people's moods.

A new study found that paroxetine -- an antidepression, antianxiety medication sold under the brand name Paxil -- may reduce hot flashes in menopausal women.

The study, conducted by researchers at 18 institutions, is published in Wednesday's issue of the Journal of the American Medical Association.

Dr. Vered Stearns, of the Sidney Kimmel Comprehensive Cancer Center at the Johns Hopkins School of Medicine, led the study of 165 menopausal women who experienced at least two to three hot flashes a day. The researchers collected data between October 2001 and March 2002. Participants filled out a questionnaire about the severity of symptoms, then were randomly assigned to take paroxetine at 12.5 or 25 milligrams, or a placebo, every day for six weeks.

At three weeks and six weeks into the study, volunteers answered additional questions about their symptoms and had vital signs measured. The women also kept daily hot flash diaries, recording the frequency and severity of their hot flashes during the study period.

The researchers found that, among the 138 women who completed the study, women who took the 25-milligram paroxetine pills had 64.6 percent fewer hot flashes -- a reduction of 3.2 flashes per day. The 12.5 mg pills reduced symptoms by 62.2 percent, or 3.3 flashes per day, while the placebo reduced them by only 37.8 percent or 1.8 flashes per day.

The study also found that many of the women taking the 25-milligram pills showed significant improvements within one week of treatment. The most frequently reported side effects were mild to moderate headache, nausea and insomnia.

Sixty percent of women taking paroxetine reported half as many hot flashes than before they started the medication -- from 6.5 hot flashes per day to 3.2 hot flashes per day. In addition, up to 30 percent of women using the medication had no flashes by the sixth week of the study.

The study was supported by GlaxoSmithKline Pharmaceuticals, the makers of Paxil. Stearns has served as a consultant to the company.

Hot flashes traditionally have been treated with estrogen and progestin hormone supplements, which can reduce their frequency by 80 to 90 percent. But results of the Women's Health Initiative study last summer blamed the hormones for increased risk of heart attack, stroke, blood clots and breast cancer, and sent women and their physicians searching for alternatives.

About 75 percent of women will experience some hot flashes around the time of menopause, according to the study's authors. This translates into more than 25 million women in the United States.

Paroxetine is "the best nonhormonal drug we know about right now," said Stearns, an assistant professor of oncology. "If a woman wants to try nonhormonal therapy, she will know within days whether it's going to work."

Stearns cautions that the drug remains experimental. The optimal dose and whether it will work for minority women are still unknown.

The physiology behind hot flashes isn't fully known, Stearns said, though scientists think they occur as falling estrogen levels throw off the central nervous system's temperature control mechanism.

In earlier studies, Stearns investigated the quick-release form of paroxetine primarily in breast cancer survivors and showed a similar reduction in hot flashes.

The possibility of using paroxetine for hot flashes emerged from the observation that women with a history of breast cancer who take certain antidepressants had fewer hot flashes. The medications that worked inhibited the brain's reuptake of serotonin, a natural chemical that modulates mood, emotion, sleep and appetite.