Severe sweating treated with Botox.

A new treatment has been approved for excessive sweating, which a team of researchers reports is surprisingly common. Until recently, few data had existed on the prevalence of the condition, known as hyperhidrosis.

So, Jonathan Kowalski of the Irvine, Calif., company Allergan and his colleagues mailed surveys about sweating to people in 150,000 U.S. households. Judging from some 96,000 replies, 2.8 percent of the U.S. population, or about 7.8 million people, would describe their sweating as excessive or abnormal, the researchers report in August Journal of the American Academy of Dermatology.

Men and women are equally affected, and armpits are the most frequently cited location of the problem, the researchers found. Among people with hyperhidrosis, less than 50 percent of women and 30 percent of men have discussed the problem with a health care professional, the researchers say.

On July 20, the Food and Drug Administration approved injections of botulinum toxin type A, which Allergan markets as Botox, for treating hyperhidrosis that doesn't improve with other nonsurgical treatments, such as antiperspirant ointments. The toxin blocks the localized release of a chemical that nerve cells need to stimulate sweating.--B.H.