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Causes of Excessive Sweating

Everyone sweats when it’s hot outside, but people who have hyperhidrosis experience excessive sweating to the point that moisture may literally drip from their hands. Hyperhidrosis causes them to sweat profusely or when there's no reason to.  

Normally, your sweat glands produce perspiration that’s carried to the skin’s surface when the air temperature rises, you develop a fever, you’re exercising, or you’re feeling anxious, nervous, or under stress. When those factors are no longer an issue, the nerves that signal sweating are put on hold.

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For the 2%-3% of the population who have hyperhidrosis, however, the sweat glands don't shut off. They sweat even when the circumstances don’t call for it: when they’re in air conditioning, or while they’re sitting and watching television. Some people even tell their doctors that they sweat in a swimming pool.

The causes of hyperhidrosis depend on the type of sweating occurring. Most times, excessive sweating is harmless. In some cases, doctors don’t know why people sweat too much. In other cases, the causes of hyperhidrosis may be a medical condition that you don’t want to miss.

What Is Hyperhidrosis?

There are two types of hyperhidrosis.

  • Primary hyperhidrosis (also called focal hyperhidrosis) causes excessive sweating in the hands, underarms, face, and feet without any apparent reason.
  • Secondary hyperhidrosis (also called generalized hyperhidrosis) causes excessive sweating all over the body or in a larger area of the body and is caused by a medical condition or medication.

Primary Hyperhidrosis Causes

If your sweat glands had an “on” switch, the glands of someone with primary hyperhidrosis would always be flipped up.

People with primary hyperhidrosis generally sweat from a certain type of sweat gland called eccrine sweat glands. These sweat glands make up the majority of the 2-4 million sweat glands in your body. Eccrine sweat glands are particularly numerous on the feet, palms, face, and armpits.

When your body is overheated, when you’re moving around, when you’re feeling emotional, or as a result of hormones, then nerves activate the sweat glands. When those nerves overreact, it causes hyperhidrosis. For instance, someone may only need to think of a situation that causes anxiety in order to break out in a profuse sweat.

Doctors aren't sure why people have primary hyperhidrosis, although it may be hereditary. Many people tell their doctors they’ve experienced excessive sweating since they were a child.

People with primary hyperhidrosis may be able to cope with non-surgical treatments, including:

  • Over-the-counter or prescription-strength antiperspirants that contain aluminum
  • Medications called anticholinergics that affect the nerve signals to sweat glands
  • A low-intensity electrical current treatment called iontophoresis
  • Botox injections for underarm sweating

Surgery is usually only considered as a last resort for people with severe sweating in their hands and underarms. Surgery may involve removing sweat glands from the area. During another procedure, called thoracic sympathectomy, a surgeon cuts and destroys the nerves responsible for sweating.

One common side effect is excessive sweating in other parts of the body, such as the chest, back, or legs. Other possible risks include bleeding into the chest and nerve problems.

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