Causes of Hyperhidrosis (Excessive Sweating)

Medically Reviewed by Brunilda Nazario, MD on September 14, 2020

What Is Hyperhidrosis?

Hyperhidrosis is excessive sweating that may or may not have an underlying cause. 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 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.

For the 1% to 2% of the population 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.

Hyperhidrosis Types

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.

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 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. 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
  • 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.

Secondary Hyperhidrosis Causes

Sweating from secondary hyperhidrosis is different from primary hyperhidrosis in that it tends to happen all over or in one general area instead of just the hands, underarms, face, or feet. Unlike primary hyperhidrosis, this type is more likely to cause sweating during sleep.

And in this case, there is something that’s causing hyperhidrosis: a medical condition or a medication.

A number of medical conditions have the potential to cause hyperhidrosis. Some of them include:

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

Uncovering the underlying condition and getting the proper treatment for it will help decrease 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.

Show Sources


John E. Langenfeld, MD, thoracic surgeon at Robert Wood Johnson University Hospital, New Brunswick, N.J.

Robert Wood Johnson University Hospital: “Hyperhidrosis Center.”

University of Maryland Medical Center: “Hyperhidrosis.”

Whitney Burrows, MD, assistant professor of surgery at the University of Maryland School of Medicine, Baltimore.

International Hyperhidrosis Society: “About Hyperhidrosis,” “Hyperhidrosis Treatment Overview,” “Oral Medications,” “Diseases and Conditions that Can Cause Hyperhidrosis,” “Causes of Secondary Hyperhidrosis: Generalized Hyperhidrosis,” “Drugs/Medications Known to Cause Hyperhidrosis.”

Mayo Clinic: “Hyperhidrosis.”

American Academy of Dermatology Association: “Hyperhidrosis: Diagnosis and Treatment.”

StatPearls: “Hyperhidrosis.”

American Family Physician: “Hyperhidrosis: Management Options.”

Merck Manual: “Excessive Sweating.”

Dermatology and Therapy: “Current and Emerging Medical Therapies for Primary Hyperhidrosis.”

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