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Harvard Commentaries
Harvard Commentaries
Reviewed by the Faculty of Harvard Medical School

Man to Man Man to Man

Help for Excessive Perspiration

September 17, 2013

By Harvey B. Simon M.D.

Harvard Medical School

Everyone perspires, and we all sweat more during the summer. But some people perspire excessively all year. Sweaty palms can sabotage a job interview with a soggy handshake. Wet armpits can make some guys change their shirts two, three, or even four times a day. And a moist smile can make a first date the last.

Although it's not a major illness, excessive sweating is far from trivial. In fact, it can be very embarrassing, and it can interfere with healthy interpersonal relationships. Call it by its medical name, hyperhidrosis, because it's a problem that deserves respect.

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Why We Sweat

Sweating is both normal and necessary. It's one of the ways the body sheds the heat that results from metabolism.

The other way is through conduction. Heat from the skin is carried into the surrounding air. When the air is hot, it's hard to dissipate heat by conduction. When the air is humid, sweat won't evaporate, making perspiration an ineffective way to get rid of heat. So the discomfort of summer is not due to heat or humidity, but to both.

When you're at rest, most of your body's heat comes from your liver, heart and muscles. But when you exercise, your muscles increase their metabolic activity; heat production increases 20 times. As a result, physical activity turns on your sweat glands even in cool weather. And when it's hot out, you can lose up to a quart and a half of sweat per hour. If you let yourself get dehydrated, though, your body will turn off the sweat faucet and your temperature will soar. That's why it's crucial to drink enough water whenever you work out, and why good hydration is particularly important during the dog days of summer.

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Two Types of Excessive Sweating

Without sweating, we'd burn up. But people with hyperhidrosis sweat more than is necessary to regulate body temperature. Excessive perspiration comes in two forms.

Generalized. When heat, humidity and exercise trigger sweating all over the body, it's a normal response to thermal stress. But whole-body sweating can also be a sign of various medical conditions, such as:

  • Metabolic disorders, including an overactive thyroid gland or diabetes
  • Infections, ranging from the flu to tuberculosis
  • Malignancies, particularly lymphomas (cancers of lymph glands)
  • Alcohol abuse, especially during alcohol withdrawal (delirium tremens)
  • Hormonal imbalances; men who've shared a bed with a woman of a certain age are well aware of the hot flashes and drenching sweats that often mark menopause, when estrogen levels bottom out. But men who undergo androgen-deprivation therapy to treat prostate cancer also suffer from hot flashes and sweats as levels of the male hormone testosterone plummet.
  • Anxiety that can cause sweating either all over the body or in localized areas, such as the palms (remember those soggy exam papers?)
  • Certain neurologic disorders; nerve cells turn on sweating by releasing the chemical acetylcholine directly into sweat glands
  • Medication side effects; the antidepressant venlafaxine (Effexor) is an example

Localized. In localized hyperhidrosis, the excess sweating is confined to the palms of the hands, soles of the feet and armpits. Underlying diseases are rarely the cause. Instead, common triggers include intense emotion (particularly anxiety) and strong odors or flavors (particularly spicy foods, citrus fruit, coffee, chocolate, and apples). Often, though, it's not possible to pinpoint the cause of localized hyperhidrosis. But in all cases, heat makes the problem worse.

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What You Can Do

Because generalized hyperhidrosis has so many possible causes, you should first get a medical evaluation to rule out or identify any underlying problems. Localized hyperhidrosis doesn't usually result from a medical condition, so you don't need a detailed check-up.

Once your doctor has cleared your overall health, you can tackle the sweating itself with these steps.

  1. Start with over-the counter anti-perspirants. Most men already use them under their arms, but few realize they can also help control sweating from other areas of they body, including the palms and soles. Look for a product that contains 10% or more of an aluminum salt, such as aluminum chloride. If ordinary antiperspirants don't help, a prescription antiperspirant containing 20% aluminum chloride hexahydrate (Drysol) may be beneficial.
  2. Try iontophoresis. This involves putting your hands and/or feet in tepid tap water while a special device passes a tiny electric current through the water. These devices are approved by the U.S. Food and Drug Administration (FDA). Each treatment takes 20 minutes or more. You can do the procedure at home. Men with pacemakers or metal implants cannot use iontophoresis. Iontophoresis is an old treatment for excess perspiration.
  3. Botulinum toxin A, better known as Botox, can halt sweating in its tracks. It blocks the release of acetylcholine from nerve endings. That's the good news. The bad news is that:
    • Treatment involves about a dozen tiny injections in each armpit.
    • The treatment is expensive.
    • It has to be repeated when it wears off in 6 to 10 months.
    • Insurance may not cover the treatment. The FDA has approved Botox for severe hyperhidrosis of the armpits.
  4. If doctors can't find any underlying medical problem, they may try to control severe excessive sweating with an anticholinergic medication. These drugs block acetylcholine in many tissues in addition to the sweat glands. But they often have uncomfortable side effects, including dry mouth, constipation and difficulty urinating. As a result, they must be used with care. They are generally reserved for very troublesome sweating problems that have not been controlled with other treatments.

Because every case of excessive perspiration is different, I can't tell you exactly how to stay dry this summer. But even if I can't provide specific advice, I can offer a generic tip for excessive sweating: Stay calm and, if possible, cool.

Harvey B. Simon, M.D. is an Associate Professor of Medicine at Harvard Medical School and a member of the Health Sciences Technology Faculty at Massachusetts Institute of Technology. He is the founding editor of the Harvard Men's Health Watch newsletter and author of six consumer health books, including The Harvard Medical School Guide to Men's Health (Simon and Schuster, 2002) and The No Sweat Exercise Plan, Lose Weight, Get Healthy and Live Longer (McGraw-Hill, 2006). Dr. Simon practices at the Massachusetts General Hospital; he received the London Prize for Excellence in Teaching from Harvard and MIT.

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