Articles & Advice

Perspiration Facts

We all sweat, but aside from a workout at the gym, few of us know why. Here are a few little-known facts about perspiration—and what you can do about it.

Q. Why do we sweat?

A. Perspiration is your body's built-in cooling system. To maintain your internal temperature of 98.6° F, sweat glands draw fluid from the bloodstream and pass the water to the skin to cool it. In addition to hot weather and exercise, spicy foods and emotions like fear and embarrassment produce sweat. By stimulating the production of adrenaline, they cause your heart and other organs to step up their activity, which stimulates heat and makes you sweat.

Q. How much sweat do we produce?

A. In extreme heat, an average person sweats about 3 pints an hour. But a person well acclimatized to heat sweats up to 8.5 pints an hour! Drinking fluids will ultimately help cool you and prevent dehydration.

Q. What is sweat?

A. Sweat is made up of water, salt, potassium and waste products. With heavy sweating, salts—which are usually reabsorbed and recycled into the bloodstream—can more easily get past the sweat glands and escape.

Q. What makes sweat smell?

A. Your body has two different kinds of sweat glands: eccrine and apocrine. By the age of three, you've developed 2-5 million eccrine glands all over your body, but only 25,000 of these glands (less than 0.5%) are found under the arms. These glands secrete a watery sweat directly onto your skin, especially in response to heat and emotion. The apocrine glands, located in the underarm and genital areas, usually don't become active until puberty. In response to stress, this sweat clings to hair follicles, and is broken down by bacteria. This is the kind of sweat you use deodorant for.

Q. Why are my underarms red or bumpy?

A. Your underarm is 1% sweat glands and 99% skin. And because underarm skin is very thin and collects fluid quickly, it is even more prone to irritation than many other parts of our bodies. Moreover, the very things we do to care for it—frequent shaving among them—can dry and irritate it. This, plus harsh deodorants and skin-on-skin and clothes-on-skin chafing, leaves many women with irritated underarm skin.

Q. How can I protect my underarms?

A. Stay hydrated to make sure your body can produce the cooling perspiration you need. Wear loose-fitting breezy clothing to keep the air circulating. Also, focus on cleanliness to inhibit odor-producing bacteria. Finally, use a gentle, nourishing deodorant to help soothe the outer layer of underarm skin that becomes irritated by routine shaving