Understanding what causes excessive sweating

If you're playing an intense sport, eating spicy foods, or giving a nerve-wracking presentation at work, you probably expect a little perspiration. But for some people, excessive sweating can occur for no apparent reason, even when they're not working out or freaking out. So what causes excessive sweating, and what exactly is hyperhidrosis?

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The official name for the medical condition of excessive sweating is hyperhidrosis. While everybody sweats, the type of excessive sweating that characterizes hyperhidrosis is unpredictable and can happen without any specific reason. In most people, internal and external factors like having a fever, hot weather, intense exercise, or even stress can cause excess sweat to form. If you have hyperhidrosis, you start intensely sweating for no real reason (NIH, 2019).

Some people with hyperhidrosis have overactive sweat glands, and others may have a family history of hyperhidrosis—the medical condition has been shown to have a genetic component for some people. A variety of medications and medical conditions can cause hyperhidrosis, too. These include anxiety, hyperthyroidism, cancer, heart disease, stroke, among others. According to research, about 4.8% of Americans (approximately 15.3 million people) have hyperhidrosis (Doolittle, 2016).

Unsurprisingly, sweating is the primary symptom associated with hyperhidrosis. But since everyone sweats on a regular basis, you may be wondering what constitutes hyperhidrosis-level sweating. In general, hyperhidrosis sweating is so intense, it's visible (i.e., you might see beads of sweat form on your skin, even if you're not exercising or moving at all). It's also common for people with hyperhidrosis to sweat through their clothes even if they're not experiencing any of the factors that normally cause sweating (like hot weather, a fever, physical activity, etc.). The kind of sweating that characterizes hyperhidrosis is usually so extreme, it interferes with daily activities and negatively impacts your quality of life. Turning a doorknob or writing on paper can be a challenge in severe cases of hyperhidrosis. 

Fungal skin infections can also be an issue for people with hyperhidrosis because of the parts of the body where sweat tends to form, like the armpits, groin, feet, etc. Athlete's foot and jock itch can commonly occur in people with hyperhidrosis and even if those issues don't occur, people with hyperhidrosis may experience soft, white, and peeling skin in the areas of the body where they sweat, as well as clammy hands and feet, increased body odor, and night sweats (AAD, n.d.).

There are two types of hyperhidrosis: primary and secondary. Primary hyperhidrosis mostly develops in people between the ages of 18 and 39. The underlying cause of primary hyperhidrosis isn't totally understood, but it's the type that has a genetic component (between 35–55% of people with primary hyperhidrosis have a family history of the condition). Most people with primary hyperhidrosis have excessive sweating in one area of the body (this is called primary focal hyperhidrosis), but it can happen all over the body, too (Lenefsky, 2018). 

Unlike primary hyperhidrosis, secondary hyperhidrosis occurs as a result of some other factor, like an underlying condition, medication, hormonal problem, or some other health issue. People who develop secondary hyperhidrosis usually start having symptoms after the age of 25 and tend to have more generalized sweating than people with primary hyperhidrosis. There's a lower likelihood of people with secondary hyperhidrosis having a family history of excessive sweating (Lenefsky, 2018). 

There's a huge variety of medical conditions that can cause secondary hyperhidrosis, some of the most common being cancer, heart disease, Parkinson's disease, spinal cord injuries, HIV, tuberculosis, stroke, and hormone imbalances like menopause or hyperthyroidism (NIH, 2019). There is also a wide range of medications that can cause secondary hyperhidrosis, including antidepressants like selective serotonin reuptake inhibitors (SSRIs), pilocarpine (a treatment option for mouth dryness), and zinc supplements (Cheshire, 2018).

Another potential cause of secondary hyperhidrosis is excessive alcohol use. Because chronic alcohol use can cause damage to the autonomic nervous system (ANS), which plays a role in sweating, excessive sweating can often occur in people who abuse alcohol (Tugnoli, 1999).

About 2.8% of the U.S. population has primary hyperhidrosis, and about half of the people who have it say they experience it in their underarms (Doolittle, 2016). 

There are different medications and treatments that address hyperhidrosis, but one important lifestyle strategy is to bathe regularly and use an antiperspirant with deodorant. Antiperspirants work by plugging the sweat ducts, and products that contain 10% to 20% aluminum chloride hexahydrate are considered the first line of treatment for underarm sweating. (NIH, 2019).

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Current version

February 28, 2020

Written by

Michelle Konstantinovsky

Fact checked by

Mike Bohl, MD, MPH, ALM

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About the medical reviewer

Mike Bohl, MD, MPH, ALM

Dr. Mike is a licensed physician and a former Director, Medical Content & Education at Ro.