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What's in Your Antiperspirant?

From the WebMD Archives

The 2 million to 4 million sweat glands in our bodies pump out several liters of perspiration every day, which probably explains why close to 100 million of us report that sweating is "sometimes" or "often" a problem. A Harris Interactive Poll found that excessive sweating negatively affects confidence, careers, and social lives -- not to mention doing a number on clothes.

Antiperspirants are the No. 1 defense against excessive sweating, but how well a product works for you depends on many factors, including its ingredients, the strength of those ingredients, how much you perspire, and even when you apply it.

"You want your underarms to be as dry as possible so that the antiperspirant's active ingredients have a chance to do their job by seeping into pores and plugging sweat ducts," says David Pariser, MD, professor of dermatology at Eastern Virginia Medical School in Norfolk.

If your armpits are damp -- as they are after you towel off from a shower -- the antiperspirant will mix with that wetness and slide off your skin instead of into the sweat ducts where you need it most. That's why it's best to apply antiperspirant at bedtime, when your underarms are dry and you've got about eight hours of relatively sweat-free slumber to allow the aluminum ingredient in antiperspirants to go to work.

Here's the information on the key antiperspirant ingredients you need to combat excessive sweating and feel fresh all day.

Aluminum. Aluminum-based compounds are the most widely used active antiperspirant ingredient because they effectively plug up sweat ducts to temporarily stop the flow of moisture to the skin. Over-the-counter clinical strength antiperspirants contain higher concentrations of aluminum.

Rumors have circulated on the Web for years that aluminum in antiperspirants can raise one's risk of breast cancer and Alzheimer's disease if the compounds are absorbed through pores or enter the skin through a shaving nick. However, "There's no scientific evidence to suggest that antiperspirant ingredients pose any sort of health risk," says Pariser. "These are urban legends that people keep perpetuating through emails."

Parabens. These preservatives help keep cosmetic products free of bacteria. However, several small studies found traces of parabens in breast cancer tumors, suggesting that they may have weak estrogen-like effects if absorbed through the skin. But the study didn't find that parabens caused breast cancer, or that the parabens were from antiperspirants.