Causes of Hyperhidrosis (Excessive Sweating)

Medically Reviewed by Dany Paul Baby, MD on February 16, 2023
4 min read

Hyperhidrosis is excessive sweating that may or may not be caused by another medical condition. People who have hyperhidrosis sweat to the point that moisture may literally drip from their hands.

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

For the 1% to 2% of people who have hyperhidrosis, 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 that’s happening. 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 need to be aware of.

There are two types of hyperhidrosis.

  • Primary hyperhidrosis (also called focal, or essential 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 can be caused by excessive heat as well as a medical condition or medication.

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

People with primary hyperhidrosis generally sweat from a certain type of gland called eccrine sweat glands. These glands make up the majority of the 2 million to 4 million sweat glands in your body. Eccrine sweat glands are 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, 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 sweat.

Doctors aren't sure why people have primary hyperhidrosis, although it may be inherited. The most common cause of excessive sweating is called primary focal hyperhidrosis. This form of hyperhidrosis affects about 1% to 3% of the population, and usually starts in childhood or adolescence.

Primary focal hyperhidrosis does not cause illness. Basically, you just sweat too much. Although it is a medical condition, it's not a sign of disease or a drug interaction. People who have it are otherwise healthy.

The symptoms of primary focal hyperhidrosis are fairly specific. It's called focal or localized because it only affects specific parts of the body, such as the underarms, groin, head, face, hands, or feet. Symptoms also tend to be symmetrical, occurring on both sides equally.

Why does it happen? Experts aren't sure, but primary focal hyperhidrosis seems to stem from a minor malfunction in the nervous system. There's some evidence that it could run in families. Many people tell their doctors they’ve had excessive sweating since they were a child.

People with primary hyperhidrosis may be able to cope with nonsurgical treatments, including:

  • Over-the-counter or prescription-strength antiperspirants that contain aluminum salts or aluminum chloride
  • Medications called anticholinergics that affect the nerve signals to sweat glands. You may take them in pill form or apply them to your skin as a cream or with a medicated wipe.
  • A low-intensity electrical current treatment called iontophoresis
  • Botox injections for underarm sweating
  • Anti-anxiety medications to manage the stress than can cause you to sweat

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.

This less common form of hyperhidrosis causes sweating all over the body – not just on the hands or feet. Secondary general hyperhidrosis is also more serious medically. It's called secondary because it's being caused by something else, such as another health condition.

One telltale sign of secondary hyperhidrosis is excessive generalized sweating at night.

What can trigger secondary general hyperhidrosis? There are many possibilities, including medical conditions and diseases. They include:

  • Menopause
  • Pregnancy
  • Thyroid problems
  • Diabetes
  • Alcoholism
  • Infectious diseases like tuberculosis
  • Parkinson's disease
  • Rheumatoid arthritis
  • Stroke
  • Heart failure
  • Cancers like leukemia and lymphoma

What about anxiety? People who are anxious – or have actual anxiety disorders – may sweat more than others. But experts say that anxious sweating isn't the same as hyperhidrosis. (But in some people, the two conditions can occur at the same time.)

Medications can also cause general excessive sweating. Medications that can cause sweating include:

  • Some psychiatric drugs
  • Some blood pressure medications
  • Some medicines for dry mouth
  • Some antibiotics
  • Some supplements

Many medications can also cause excessive sweating. Tell your doctor if you take:

Uncovering the other medical condition and getting the proper treatment for it will help lessen the sweating of secondary hyperhidrosis. That’s why it’s best to tell your doctor when you’re having a problem with sweating, so that you can uncover the reasons behind it and get it treated.