QUESTION

I have a friend who said she never sweats—at all, no matter how hot she gets. Is that possible?

ANSWER

Many people don’t perspire much under the same conditions that leave their companions dripping. But never sweating is different. Called anhidrosis, it’s a condition that affects a small number of people. While some don’t sweat at all, the more common version is hypohidrosis—loss of sweating only in certain areas of the body. But both kinds are collectively referred to as anhidrosis.

Never having to worry about damp underarm patches, dripping palms or sweaty feet might sound pretty good. However, you really need to sweat, even if it isn’t always socially convenient. Perspiring is the body’s air- conditioning system, and not being able to can lead to overheating, heat exhaustion and heatstroke, a dangerous condition that can be fatal.

What causes anhidrosis?

Sweat is about 99% water plus small amounts of salt, proteins, carbohydrates and urea (most urea is excreted in urine). Note: Contrary to popular belief, sweat does not “cleanse” the body by eliminating toxins. Those are eliminated through urine and feces.

People are normally born with about two to five million sweat glands. Some people—fortunately, not many—are born with a decreased number of healthy sweat glands, a medical condition called congenital anhidrosis. But it’s not very common. The more common cause of anhidrosis is dehydration from not drinking enough fluids. You can’t make sweat when your body is “thirsty.” So if you notice that you’re not sweating when normally you would—such as during hot weather or when you’ve just worked out—you might need to drink more water.

Persistent anhidrosis also can develop from other causes, including…

  • Injuries, such as severe burns and radiation therapy.
  • Diseases, such as diabetes, alcohol abuse and autoimmune diseases (for instance, psoriasis).
  • Medications, such as morphine, Botox and some antipsychotic drugs…or a class of drugs called carbonic anhydrase inhibitors, which includes medications used to treat glaucoma, epilepsy, high blood pressure, stomach ulcers and osteoporosis.
  • And in some cases, the cause of anhidrosis isn’t known.

Note: Although it is not known exactly why, tattoos can slightly decrease sweating in the area involved.

Do You Have a Nonsweating Problem?

The absence of perspiration seems like a no-brainer clue that you might have anhidrosis—particularly if after exertion, especially in hot weather, you also often feel dizzy, weak, have muscle cramps and feel hot or flushed. But you might not realize that you’re not sweating when you should be. Surprisingly, excessive sweating in one area of your body can be a sign of hypohidrosis. If one part of your body that should sweat doesn’t, your body may compensate by triggering areas where you do have active sweat glands to sweat more.

If you have a persistent nonsweating issue, let your doctor know. Getting a medical diagnosis of anhidrosis generally starts with a medical history and physical exam. Finding the cause might require further testing, such as a thermoregulatory sweat test (TST), which evaluates the autonomic nervous system by checking the integrity of pathways from the central nervous system to cutaneous sweat glands.

Treatment depends on the cause and how widespread the condition is. If only a limited area of skin is affected, treatment may be unnecessary.

Sometimes treating the condition that is causing anhidrosis improves or eliminates the problem—for instance, getting blood sugar under control, or stopping or changing a medication. If the problem is a blocked sweat duct, exfoliants or steroid drugs to decrease inflammation of sweat glands can help. In many cases, the best or only treatment is to avoid activities and situations that raise body heat.

No-Sweat Ways to Cool Down

If you know you have anhidrosis, you need to stay alert to warning signs of heat exhaustion and heatstroke and learn what steps you need to take to cool your body…

  • Stay in a cool area on hot days.
  • Avoid exertion in the heat.
  • Rest and get cool as soon as you start to have symptoms of overheating.
  • Drink enough water to avoid dehydration, which makes overheating worse.
  • Wet your skin with water, either with a damp cloth or by spritzing. The water will act like sweat to help cool you down.
  • Keep clothing light, loose-fitting and light-colored. White is best, but cream and beige are also OK and better than navy, black and other dark colors, which tend to absorb more heat.
  • If symptoms of being overheated continue for more than an hour, get medical attention.