Rising from the chest, a warmth flashes throughout the upper body reaching full intensity within a minute, fading gradually before several more set in — a metronome signalling a new beginning in a woman's life.

The age of menopause, and the onset of potentially miserable hot flashes, varies greatly from developing to developed world, with the average American woman beginning the years-long transition at age 49.

Although researchers don't fully understand the mechanisms of the heat flashes, a body of evidence implicates reduced levels of estrogen as the primary cause. This in turn gives rise to changes in the brain's hypothalamus, which functions as the body's thermostat, causing a change in body temperature. Most drug therapies on the market treat the symptoms of menopause by attempting to restore a former hormonal balance with estrogen or a combination of estrogen and progestin, the synthetic form of the hormone progesterone.

However, the U.S. Food and Drug Administration (FDA) on Saturday announced approval for the first non-hormonal treatment for vasomotor symptoms associated with menopause, a therapy containing the selective serotonin reuptake inhibitor (SSRI) paroxetine mesylate, marketed by the name Brisdelle.

The new medication is intended to offer a non-hormonal treatment for the 75 percent of menopausal women who experience the discomforting symptoms, which may persist for five years, or even longer for some women.

"There are a significant number of women who suffer from hot flashes associated with menopause and who cannot or do not want to use hormonal treatments," Dr. Hylton V. Joffe, director of the Division of Bone, Reproductive, and Urologic Products in the FDA's Center for Drug Evaluation and Research. "Today's approval provides women with the first FDA-approved, non-hormonal therapeutic option to help ease the hot flashes that are so common in menopause."

The medication contains 7.5 milligrams of paroxetine, less than the amount used in medications such as Paxil and Pexeva for the treatment of major depressive disorder, obsessive-compulsive disorder, panic disorder, and generalized anxiety disorder. Even with a lower dose of paroxetine, the menopause therapy carries a warning of increased suicidality that has been shown in children and young adults. Addditional labeled warnings include a possible reduction in the effectiveness of tamoxifen if both medications are used together, an increased risk of bleeding, and a risk of developing serotonin syndrome.The most common side effects associated with Brisdelle, however, are headache, fatigue, and nausea.

The therapy was tested for safety and efficacy in two randomized, double-blind, placebo-controlled studies in a total of 1,175 women with moderate to severe menopausal symptoms, which varied from 7-8 instances of hot flashes per week to 50-60 in the most aggravated cases.

In the two studies, the therapy was shown effective in reducing the symptoms of hot flashes, though researchers have little idea why.