Hyperhidrosis is a medical condition that causes excessive sweating (perspiration). It usually affects the armpits, hands or feet. However, most areas of the skin’s surface can be affected.

Sweating helps maintain body temperature, skin hydration and fluid and electrolyte balance. People sweat in response to numerous factors (e.g., warm temperatures, physical exertion, anxiety). However, individuals with hyperhidrosis sweat excessively, even when these triggers are not present (e.g., in cool temperatures, during periods of rest).

Primary hyperhidrosis is a chronic (ongoing) condition that is associated with overactive sweat glands. Secondary hyperhidrosis occurs in response to a separate medical condition (e.g., overproduction of thyroid hormones [hyperthyroidism]). Hyperhidrosis can be further classified according to its cause and/or location. For example, excessive sweating caused by the hypothalamus region of the brain, which regulates body temperature, is called hypothalamic hyperhidrosis.

Visible signs of hyperhidrosis are often obvious and may include underarm stains, dripping palms or wet clothing. Diagnosis of hyperhidrosis is often based on the patient’s symptoms and medical history. If secondary hyperhidrosis is suspected, additional testing (e.g., x-ray, urinalysis) may be performed to identify or rule out any potential underlying conditions.

Secondary hyperhidrosis may cease if its underlying cause is identified and successfully treated. Treatment of primary hyperhydrosis focuses on symptom relief and may include use of antiperspirants, surgery or medications.

Hyperhidrosis is a medical disorder that causes excessive sweating (perspiration). It typically affects the armpits, hands or feet. However, it may impact any part of the skin’s surface except for the lips, external ear canal and sex organs, which do not have the capacity to produce sweat.

Sweating is a natural process that helps maintain body temperature, skin hydration and fluid and electrolyte balance. It is regulated by the body’s sympathetic nervous system. People sweat in response to warm temperatures, physical exertion and situations that cause anxiety, anger, embarrassment or fear. However, the excess sweating associated with hyperhidrosis occurs without these triggers. Therefore, patients with hyperhidrosis may sweat even in cool temperatures or during periods of rest.

Hyperhidrosis is believed to be associated with overactive sweat glands. A sweat gland is a tube of cells that secretes sweat through the pores of the skin. The body contains millions of sweat glands, which can be divided into two main types:

• Eccrine glands. Sweat glands which are present at birth and open directly onto the skin’s surface. These are the most abundant sweat glands in the body, and produce the majority of underarm sweat.
  
  
• Apocrine glands. Sweat glands which develop in regions with numerous hair follicles (e.g., scalp, underarms), and are triggered by emotions. Apocrine glands begin to produce sweat following puberty. They have minimal, if any, impact on temperature regulation.
  
  

  

Both types of sweat glands are located in the dermis (middle layer of the skin), and both have the same physical structure. Sweat is produced in a part of the gland that is coiled. When the gland is stimulated, the cells secrete perspiration, which travels from the coiled part of the gland through a long, hollow tube (duct) to an opening (pore) on the outer surface of the skin.

The sweat glands are stimulated by different regions of the brain. For instance, the hypothalamus controls temperature-related (thermal) sweating, which occurs in response to factors such as heat, humidity and physical exertion, whereas the cerebral cortex regulates sweating caused by emotions. 

Hyperhidrosis typically begins in childhood or adolescence. It affects men and women equally. Although hyperhidrosis generally poses no immediate health risks, the condition can have an effect on everyday activities. For instance, patients with sweaty palms may have difficulty grasping objects, and those with underarm-related hyperhidrosis may need to change their clothes frequently throughout the day. The condition can also lead to various skin diseases (e.g., fungal infections, contact dermatitis).

Hyperhidrosis can be a source of embarrassment for many patients, and may have social, professional and emotional ramifications. For these reasons, cases of hyperhidrosis are believed to be underreported. Therefore, the exact incidence of the disorder is not known.

Hyperhidrosis can be either primary (focal) or secondary, depending on its cause. Individuals are typically diagnosed with primary hyperhidrosis when the disorder is localized (confined to the armpits, hands and feet), and no underlying medical condition can be identified. Secondary hyperhidrosis is diagnosed when excessive sweating occurs in response to a separate medical condition (e.g., hyperthyroidism, hypoglycemia) or other factors (e.g., spicy foods, drugs, stress).

Hyperhidrosis can be further classified according to its cause. For instance, excessive sweating can be caused by the hypothalamus region of the brain, which regulates the body’s temperature. This form is called hypothalamic hyperhidrosis, and can be triggered by numerous factors (e.g., physical exertion, underlying medical conditions, drugs).

Location can be used to classify hyperhidrosis as well. For instance, excessive sweating in the hands is known as palmar hyperhydrosis, excessive sweating in the underarms is known as axillary hyperhidrosis and excessive sweating in the face and/or feet is known as plantar hyperhidrosis.

Hyperhidrosis can also be emotionally induced. This form is known medically as cortical hyperhidrosis because it is related to the emotional, mental and sensory processes of the cerebral cortex region of the brain. Cortical hyperhidrosis is one of the most common types of excessive sweating. It affects the palms, soles and armpits. In most cases, sweating in the armpits diminishes or stops during sleep and increases during more concentrated emotional, mental or sensory stimulation.

Hyperhidrosis may affect the following parts of the body:

• Taste buds. Hyperhidrosis may result from eating spicy foods or drinking certain beverages (e.g., alcohol). It may also occur in response to injury or disease of the parotid gland (a type of salivary gland), or in relation to some disorders of the central nervous system (e.g., encephalitis). Hyperhidrosis caused by the consumption of spicy foods most commonly affects children and young adults in warm environments. Sweat typically appears shortly after consumption either above the upper lip or on the cheeks. The duration of sweating may be brief or last as long as the food is in the body.
  
  
• Spinal cord. Hyperhidrosis may occur as a result of any injury or disease process that severs the spinal cord or otherwise interferes with proper functioning of spinal neurons. Hyperhidrosis in this region often appears suddenly and may last indefinitely. Spinal sweating appears below the level where the spinal cord was severed or interrupted.

Another type of hyperhidrosis called compensatory hyperhidrosis occurs when the sweat glands of a certain area of the body produce excess sweat to compensate for underactive sweat glands in another bodily region. This commonly affects people with hyperhidrosis that has been successfully treated surgically or with Botox injections. Patients with obstructed sweat glands from hyperhidrosis (miliaria) may experience compensatory hyperhidrosis at an alternate location, as may diabetes patients with anhidrosis (absence of sweating).

The cause of primary (focal) hyperhidrosis is not known. However, secondary hyperhidrosis can have numerous causes. Depending on the type of hyperhidrosis, causes can range from emotions (e.g., stress) to a serious underlying medical disorder (e.g., heart disease, tuberculosis). One of the more common causes includes heredity. Individuals who are genetically predisposed to hyperhidrosis often have sweaty palms and feet.

Spicy foods and hot beverages, and those containing caffeine and alcohol, can also trigger hyperhidrosis, as can some types of drugs (e.g., certain antipsychotic medications). Hyperhidrosis can also result from overdose of an analgesic (e.g., aspirin, acetaminophen) or hormonal factors, such as hot flashes caused by menopause, or reduced levels of the male hormone testosterone (in men).   

Other potential causes of hyperhidrosis include:

• Excessive heat
• Hypoglycemia (low blood sugar)
• Exercise
• Fever
• Toxins (e.g., arsenic, drug or alcohol addiction)
• Spinal cord injuries
• Injury or disease of the parotid (salivary) gland
• Metabolic disorders (e.g., diabetes, hyperthyroidism)
• Infection (e.g., tuberculosis)
• Disease (e.g., malaria, certain cancers)
• Disorders of the central nervous system (e.g., encephalitis)

In addition, a small amount of individuals have an abnormal number and/or distribution of eccrine sweat glands. In some instances, this rare occurrence may be responsible for causing hyperhidrosis. 

Primary hyperhidrosis usually first appears during puberty or early adolescence and continues throughout adulthood. Secondary hyperhidrosis may develop at any time in response to a separate medical condition (e.g., hyperthyroidism) or other factors (e.g., stress). Visible signs of hyperhidrosis are often obvious and may include underarm stains, dripping palms or wet clothing.

The most commonly affected areas are the armpits, palms of the hands and soles of the feet. However, hyperhidrosis can impact any part of the skin’s surface except for the lips, external ear canal and sex organs, which do not have the capacity to produce sweat.

Individuals with underarm hyperhidrosis may experience the following symptoms:

• Softening, whitening or cracking of the skin from persistent wetness
  
  
• Small, itchy rashes caused by sweat trapped under folds of skin (prickly heat)
  
  
• Inflammation or irritation of the affected area
  
  
• A stinking odor may emanate from the affected area (bromhidrosis) due to overgrowths of sweat–related bacteria

It is recommended that individuals who experience a marked increase in sweating or any other symptoms of hyperhidrosis consult their physician.

Diagnosis of hyperhidrosis typically begins with a complete medical history and a thorough physical examination. The physician will usually address factors such as:

• The part of the body initiating the sweating response
  
  
• The rate of sweat production
  
  
• Whether sweating occurs during the day, at night or a combination of the two
  
  
• Whether sweating affects one region (localized) or occurs throughout the skin (generalized)
  
  
• The impact of excess sweating on the patient’s quality of life

Hyperhidrosis can usually be diagnosed by the patient’s history alone. In some instances, an iodine starch test may be performed to outline the exact area of skin affected. The site will be sprayed with a mixture of starch and iodine, which causes the areas that produce sweat to turn black.

If secondary hyperhidrosis is suspected, additional tests may be performed to identify or rule out potential causes of the disorder. These tests may include:

• Thyroid function test. A blood test that may reveal high levels of thyroid hormones (hyperthyroidism).
  
  
• Blood glucose level test. A blood test to check for high blood glucose (hyperglycemia) or diabetes.
  
  
• Urinalysis and imaging tests (e.g., x-ray). These tests may indicate or rule out cancerous cells or tumors as a cause of hyperhidrosis.

Secondary hyperhidrosis may cease if its underlying cause is identified and successfully treated. For instance, patients with emotionally induced hyperhidrosis may benefit from taking anti-anxiety medications or antidepressants. Primary hyperhydrosis, however, is chronic (ongoing) in duration. Therefore, its treatment focuses on relief of symptoms.

Though effective, many treatments for hyperhidrosis have been associated with side effects. Patients are encouraged to consult a physician before beginning any treatment plan. Treatment of hyperhidrosis often depends on the location and magnitude of symptoms.

Some of the more common methods of symptom relief include:

• Antiperspirants (e.g., aluminum chloride). Work by obstructing the sweat glands. Over-the-counter antiperspirants are usually only effective at treating very mild symptoms. Applied nightly, prescription–strength antiperspirants may be effective at treating patients with moderate hyperhidrosis of the underarms. The time between topical applications may be gradually lengthened if symptoms improve. Treatment with strong antiperspirants may be limited due to skin irritation. Some methods of application can lessen skin irritation, such as applying antiperspirant in the evening and washing it off in the morning.
  
  
• Botox. Interrupts chemical messages that tell sweat glands when to sweat. It is injected where hyperhidrosis occurs (e.g., underarm, hand, foot), freezing the nerve that stimulates sweat production. Although Botox helps to improve hyperhidrosis, it usually becomes less effective after six months to a year. As a result, patients will require periodic injections of Botox to maintain the effects. This can become expensive. Botox injections into the palms can also cause temporary weakening of a person's grip.  
  
  
• Surgery. In patients with moderate to severe cases of hyperhidrosis, two types of surgery may be used to control sweating:
  
  
• • Sweat gland resection. Usually performed on patients with severe hyperhidrosis of the armpits. This procedure removes the sweat glands that cause hyperhidrosis and may require skin grafts.
    
    
  • Endoscopic transthoracic sympathectomy (ETS).  Clipping of the nerves that carry messages to the sweat glands using an instrument that has a small lighted camera (endoscope). This is the most common form of surgery used in the treatment of hyperhidrosis. It is considered the most effective surgical treatment for the condition. Occasionally, the effects of this surgical procedure may not be permanent, or may restrict arm movement. ETS may also cause uncomfortable skin warmth or dryness in some cases.

Typically, surgical options are considered only after non-surgical treatment methods have failed to improve symptoms. Surgery may result in compensatory sweating, in which excessive sweating transfers from one area of the body to another. Less common side effects of surgery include gustatory sweating (facial sweating that follows eating or smelling foods) and Horner’s syndrome (a condition characterized by a drooping eyelid, constricted pupil and loss of sweating on one side of the face). 

• Iontophoresis. A process that involves passing electric currents through the skin of the affected area. Iontophoresis works by temporarily blocking sweat glands. It is most often used to treat hyperhidrosis of the palms of the hands or soles of the feet, but may be used to treat hyperhidrosis of the armpits as well. Iontophoresis is painless and has no side effects, though it may be no more effective than a strong antiperspirant for some people. Frequent treatments are necessary to control symptoms and sessions are time consuming.
  
  
• Beta blockers. A class of drugs used to treat high blood pressure and heart disease. Beta blockers may help treat hyperhidrosis related to specific emotional events by reducing the emotional stimulus that leads to hyperhidrosis. Beta blockers are not suitable for some patients with asthma or vascular (blood vessel) disease.
  
  
• Anticholinergic medications. These may be effective at reducing instances of hyperhidrosis by interrupting the neurotransmitter responsible for sweat secretion (acetylcholine). However, they are not often prescribed for this condition due to possible side effects (e.g., dry mouth, blurred vision, constipation).

There are no known prevention methods for hyperhidrosis.

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following hyperhidrosis-related questions:

1. Is my hyperhidrosis primary or secondary?
   
   
2. What may be causing my hyperhidrosis?
   
   
3. What tests will you use to determine the cause of my hyperhidrosis?
   
   
4. Is my hyperhidrosis a cause for concern?
   
   
5. What are my treatment options? How effective are they?
   
   
6. Is it possible I could develop this problem in other areas of my body?
   
   
7. What can I do to minimize my hyperhidrosis?  
   
   
8. Are my children at risk for hyperhidrosis as well?