A treatment made famous for fighting wrinkles may also provide lasting relief from another embarrassing condition: excessive underarm sweat.

The first long-term study of Botox injections in the treatment of the common sweating disorder shows the injections can safely reduce underarm sweat for up to two years.

Known in medical terms as axillary hyperhidrosis, the condition affects more than a million people in the U.S. People with this condition sweat up to four times more than normal in order to maintain a normal body temperature.

People with the disorder often suffer from difficulty in social situations and say it significantly interferes with their daily activities.

"These long-term data demonstrate that Botox for severe primary axillary hyperhidrosis over a two-year period is a safe and effective therapeutic option for patients who otherwise struggle with substantial impairment," says researcher Dee Anna Glaser, MD, professor of dermatology and vice chairman of dermatology at Saint Louis University School of Medicine, in a news release.

The FDA approved Botox (botulinum toxin type A) for treatment of axillary hyperhidrosis that can't be resolved with prescription creams or antiperspirants in July 2004.

Read WebMD's "Excessive Sweating: Embarrassing, Treatable"

Botox Offers Lasting Relief

In this three-year study, researchers examined the safety, effectiveness, and cost of repeated treatment with Botox injections on people with axillary hyperhidrosis and the impact of the treatment on their quality of life.

The study involved 193 people who had participated in an earlier one-year clinical trial of Botox for hyperhidrosis. They were given the option to continue treatment every eight weeks if symptoms persisted under this follow-up study.

In the follow-up study, researchers found Botox continued to be effective with repeated treatment. After the first treatment, 82 percent had up to a 75 percent reduction in sweat production in four weeks after the injection.

Four weeks after treatments two and three, 79 percent experienced the same degree of relief.

Overall, 94 percent of patients required four or fewer Botox injections to control their symptoms during the two-year study.

Read WebMD's "Learn More about Botox"

Botox May Ease Social Stigma of Sweat

The study also found that the treatment had a positive effect on the patients' quality of life, for example:

Before treatment, 66-72 percent of patients were somewhat or very dissatisfied with their ability to perform their current work activities, compared with 9-20 percent after treatment. The number of patients who reported feeling "emotionally damaged or injured" due to their hyperhidrosis reduced by about half before and after treatment, from 76-83 percent to 32-42 percent. Participants reported significantly less limitation in interpersonal and social situations. Before treatment 17-33 percent said they were somewhat or very satisfied with their ability to perform nonwork activities. After treatment, that proportion increased to 78-88 percent.

Glaser presented the results of the study this week at a meeting of the American Academy of Dermatology in Chicago. Funding for the study was provided by Allergan, Inc., which produces Botox.

Read WebMD's "Who's Using Botox and Why?"

By Jennifer Warner, reviewed by Michael W. Smith, MD

SOURCES: Annual Meeting of the American Academy of Dermatology, Chicago, July 20-24, 2005. News release, American Academy of Dermatology.