What Is Excessive Sweating?

Ask Healthy Living: What's 'Normal' When It Comes To Sweat?

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Why do I sweat so bad when I exercise?

-- Denise, 56, Mokena, IL

We've gotten some variation of this question from several readers: why do some people sweat more than others? Why do some people sweat from their faces, while others mostly sweat from their hands? When is sweating considered excessive and why am I sweating anyway?

So we spoke with Dr. Lyall Gorenstein, surgical director at the Columbia University Hyperhidrosis Center in New York and Dr. Noel Perin, director of minimally invasive spinal surgery, Department of Neurosurgery at NYU Langone Medical Center and an expert in treating complex hyperhidrosis.

Let's start with the basics: the primary purpose of sweating is to cool your body down. "Sweating is the body’s natural, neurological response to cool the body by stimulating the sweat glands to produce moisture that cools the body by drawing heat from the body during evaporation," Perin tells HuffPost Healthy Living. "Because everyone’s body is different, the response differs from one individual to another, producing varying levels of perspiration."

When your body temperature rises, whether because of sweltering external temperatures, exercise or hormonal changes (often associated with menopause), it stimulates the two to five million sweat glands that are distributed under your skin. These glands exist throughout the body, though they have higher concentrations in certain areas like the palms of the hands and the soles of the feet.

Perspiration works because it carries the heat generated by your body to the skin's surface, where it evaporates into the atmosphere, lowering overall internal temperature. Think of a bead of sweat as a vehicle for heat conducted by your body: it transports body heat to the surface, where it can diffuse into the external world. And that protects the integrity of your cells and organs from the dangers of overheating.

A secondary, less pronounced purpose to sweating is to help shed the body of waste that occurs as a natural byproduct of cell metabolism, according to Gorenstein.

But why do some people sweat more than others? Among the range of sweating that is considered normal -- that is, functional, predictable and not associated with a medical condition -- there is no known reason for the variation in sweating. "If we're talking about otherwise healthy individuals, which is to say not people who are obese or have another condition that could contribute, it's simply a physiological variation," Gorenstein tells HuffPost Healthy Living. "Just like how the average resting body temperature is 98.6, but many people exist on a bell curve around that."

Since sweating is a normal, physiological response to exercise, chances are that sweating during exercise -- even if you are sweating more profusely than your neighbors on the treadmill -- is not an indication of a problem. When in doubt, it's always better to have that confirmed by a doctor.

However, if the sweating occurs not just during exercise, but at random -- as a stress response or when you are at rest or in a controlled temperature environment -- it could indicate a condition known as hyperhidrosis. One telltale sign of hyperhidrosis is that you'll often sweat profusely from one specific area of the body, most often the palms of your hands or soles of your feet, but also sometimes the armpits.

"It can reach a point of socially uncomfortable results," says Perin. "Everything from minor annoyances such as smudged writing paper to much greater issues like difficulty holding a pen or the social discomfort caused by soaked clothing and wet handshakes."

Sometimes excessive sweating can be caused by another condition in what is called secondary hyperhidrosis. Infectious disease, hyperthyroidism, menopause and some cancers can cause hyperhidrosis, according to the Mayo Clinic, though Gorenstein has found that obesity is the most common cause of secondary hyperhidrosis.

But people with primary hyperhidrosis very often begin to experience it in early childhood or even infancy, according to Gorenstein. "Patients will tell me stories about leaving tracks on the floor as toddlers," he says. Primary hyperhidrosis is to some extent hereditary. In fact, WebMD reported that about 50 percent of hyperhidrosis cases can be traced to family history.

No one is sure what the mechanism for primary hyperhidrosis is, beyond the understanding that it is a neurological response. Gorenstein has conducted a series of clinical studies comparing hyperhidrosis patients to a control group of normal sweaters: monitoring the brains of study participants using an fMRI machine, he and his colleagues showed the group visually disturbing images to cause anxiety and stress response. They demonstrated that when patients with primary hyperhidrosis looked at the pictures, their hands began to sweat. The control group did not sweat, though they did have other measures of sympathetic response, such as quickened pulse.

For hyperhidrosis patients, treatment options vary: while some mild forms respond to prescription-strength topical antiperspirants, other options include water iontoforesis, botox injections in the armpits (an FDA-approved use) or, in extreme cases, surgical intervention.

While hyperhidrosis can be debilitating, especially socially, it is not dangerous on its own. It can, in some rare instances, be associated with a dangerous condition and should be diagnosed properly for that reason. Likewise, exercise-induced sweat, even at above average volume, isn't anything to worry about.

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