Excessive sweating can be attacked on multiple fronts
Published 6:47 pm, Monday, July 2, 2012
DEAR DOCTOR K: I sweat a lot, mostly my underarms and palms. Is it possible to sweat too much? What can I do about it?
DEAR READER: Excessive sweating is called hyperhidrosis. This condition isn’t usually dangerous, but it can be embarrassing and inconvenient.
As in your case, it’s the underarms and palms where the sweating is most prominent. Excess sweating also can occur in the feet and groin.
Why do some people sweat too much? In fact, why do we sweat at all? Sweat cools the body as it evaporates. It helps us to cool off when our body temperature is too high. When we exercise, for example, the heat produced by our working muscles heats up the body too much.
Why do we break out in a sweat when we cross the street and suddenly notice that there’s a car speeding toward us? Because the brain assumes that we are about to run — and overheat our body.
Sweating starts in the brain. The brain senses that we need to cool off. It sends signals through nerve fibers that are part of the sympathetic nervous system. Some of these sympathetic nerve fibers end right next to sweat glands under the skin. When those nerve endings pump out a chemical messenger called acetylcholine, it turns on the sweat glands. These little glands start to make sweat and release it up to the surface of the skin. When the sweat evaporates, the body cools.
Most people with hyperhidrosis are extra-sensitive to the acetylcholine signal. They produce several times more sweat than average. They’ve been sweating too much most of their lives.
When a person suddenly starts to sweat too much for the first time in his life, I begin to worry that he might have developed a medical condition that can cause excess sweating, particularly chronic infections or hormonal conditions.
Topical antiperspirants are the first choice for underarm sweating. They are also effective on hands and feet. Look for a preparation containing 10 percent to 20 percent of an aluminum salt such as aluminum chloride. Prescription-strength antiperspirants are also available. For most of my patients with hyperhidrosis, this fixes the problem.
A procedure called iontophoresis treats excessive sweating on the hands, feet and underarms. The affected body parts are submerged in water for 20 to 30 minutes while a mild electric current passes through the water. Iontophoresis appears to temporarily block sweat glands.
Botulinum toxin A (Botox) injections treat underarm hyperhidrosis by blocking acetylcholine. They are also effective for hands and feet. Multiple injections are required, but the effect lasts up to 10 months.
Rarely, surgery is needed to remove the affected sweat glands. Don’t even consider surgery unless nothing else works.
When I was in medical school, antiperspirants were the only solution for sweating too much — and they didn’t always work. Today, we are fortunate to have more treatment options.
Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA.