Hyperhidrosis (hi-pur-hi-DRO-sis) is frequent or constant excessive sweating. Sweating is your body's mechanism to cool itself. However, some people sweat in amounts greater than needed to cool the body, a condition called hyperhidrosis.

Hyperhidrosis usually affects the palms of the hands, soles of the feet and underarms. Besides disrupting normal daily activities, hyperhidrosis can cause social anxiety or embarrassment.

Symptoms

Although when, where and how much you sweat varies widely, most people sweat when they exercise or exert themselves, are in a hot environment, or are nervous, anxious or under stress. The excessive sweating experienced with hyperhidrosis far exceeds such normal sweating.

Signs and symptoms of hyperhidrosis include:

• Frequent, noticeable, excessive sweating that can soak through clothing
• Abnormally excessive and bothersome perspiration on your feet, underarms, head or face
• Clamminess or dripping of sweat droplets on the palms of the hands or the soles of your feet

Hyperhidrosis is defined as sweating that disrupts your normal activities. Episodes usually occur at least once a week without an obvious reason.

For some people, hyperhidrosis interferes with their social life. People may have trouble working or enjoying recreational activities with constantly wet hands — or become withdrawn due to self-consciousness about shaking hands with others, having stained shirts or potential body odor.

Causes

Your skin has two types of sweat glands: eccrine and apocrine. Eccrine glands occur over most of your body and open directly onto the surface of your skin. Apocrine glands open into the hair follicle, leading to the surface of the skin. Apocrine glands develop in areas abundant in hair follicles, such as on your scalp, armpits and groin.

The cause of hyperhidrosis stems from your body's temperature regulation system, specifically your sweat glands.  When your body temperature rises, your autonomic nervous system stimulates these glands to secrete fluid onto the surface of your skin, where it cools your body as it evaporates. This fluid (perspiration) is composed mainly of water and salt (sodium chloride) and contains trace amounts of other electrolytes — substances that help regulate the balance of fluids in your body — as well as substances such as urea.

There are two types of hyperhidrosis. The cause depends on the type.

Focal hyperhidrosis
Focal hyperhidrosis affects your palms, soles and sometimes underarms, usually while you're awake. Episodes often start before age 20. Sweating on your palms and soles is usually due to emotional stress, and it may be that focal hyperhidrosis occurs as an exaggerated response to emotional stimuli. But doctors don't consider it to be a psychological disorder. In fact, focal hyperhidrosis isn't usually associated with any underlying condition. It may have a genetic component, as it often runs in families.

Generalized hyperhidrosis
This type of hyperhidrosis affects large areas of the body. It can occur for no apparent reason but also may have an underlying cause, such as:

• Medication
• Menopause hot flashes
• Low blood sugar
• Overactive thyroid
• Leukemia
• Lymphoma
• Heart attack
• Infectious disease

Complications

Complications of hyperhidrosis include:

• Fungal nail infections. People who sweat profusely are prone to many types of fungal infections. That's because fungi thrive in warm, moist environments, such as sweaty shoes. That's also why you're more likely to get an infection in your toenail than in your fingernail. A nail infection usually begins as a white or yellow spot under the tip of your nail. As the fungal infection spreads deeper, your nail may discolor, thicken and develop crumbling edges. Sometimes your nail may separate from the nail bed, and the skin around it may become red and swollen. You may even detect a slight odor.
• Bacterial infections and warts. Hyperhidrosis can contribute to bacterial infections, especially around hair follicles or between your toes. It's also associated with warts. When you have hyperhidrosis, warts may take a while to go away after treatment and they have a tendency to recur.
• Social and emotional consequences. People with hyperhidrosis typically have excessive sweating of the soles and palms, which may produce clammy hands and unpleasant foot odor. As a result, they can experience significant psychological, social, educational and occupational consequences.
• Other skin conditions. Certain skin conditions, such as eczema and skin rashes, occur more frequently in people with hyperhidrosis. It may be that excessive sweating exacerbates skin inflammation.