(See also Introduction to Sweating Disorders.)
People with excessive sweating (hyperhidrosis) sweat profusely, and some sweat almost constantly.
Although people with a fever or those exposed to very warm environments sweat, people with excessive sweating tend to sweat even without these circumstances.
Excessive sweating may affect the entire surface of the skin but is often limited to certain parts of the body (called focal excessive sweating). The parts most often affected are the palms of the hands, soles of the feet, forehead, and armpits. Sweating in these areas is usually caused by anxiety, excitement, anger, or fear. Although such sweating is a normal response, people with excessive sweating sweat profusely and under conditions that do not cause sweating in most people.
Some people also sweat around the lips, nose, and forehead when they eat hot, spicy foods (called gustatory sweating). Gustatory sweating is normal, but certain disorders can increase such sweating, such as diabetes that affects the nerves, shingles affecting the face, brain disorders, certain disorders affecting the autonomic nervous system in the neck, and certain injuries affecting the nerves to the salivary gland in front of the ear (the parotid gland).
Excessive sweating that affects most of the body is called generalized excessive sweating. Usually, no specific cause is found. However, a number of disorders can cause generalized excessive sweating, including heat exposure and fevers.
Some Causes of Excessive Sweating
Severe, chronic wetness can make the affected area white, wrinkled, and cracked. Sometimes the area becomes red and inflamed. The area may emit a foul odor (bromhidrosis) due to the breakdown of sweat by bacteria and yeasts that normally live on the skin. Clothing may also become soaked with sweat.
People who sweat excessively are frequently anxious about their condition, and it may lead to social withdrawal. This anxiety may make the sweating worse.
Excessive sweating can be controlled to some degree with commercial antiperspirants. However, stronger treatment is often needed, especially for the palms, soles, armpits, or genital area. A prescription-strength aluminum chloride solution may help. At night, the person first dries the sweaty area and then applies the solution. In the morning, the person washes the area. At the start of treatment, the person must apply the solution several times until the sweating is controlled. Then an application once or twice a week is sufficient to maintain relief for as long as necessary. The solution should not be applied to inflamed, broken, wet, or recently shaved skin. Sometimes doctors give the person an anticholinergic drug (such as glycopyrrolate or oxybutynin) to take before applying the solution to prevent sweat from washing the aluminum chloride away. However, these drugs can cause side effects that lead people to stop using them (see Anticholinergic: What Does It Mean?).
Tap-water iontophoresis, a process in which a weak electrical current is applied to the sweaty areas (typically palms or soles) for 10 to 20 minutes, is sometimes used. This routine is done daily for 1 week and then repeated weekly or about twice per month.
Botulinum toxin type A can be injected directly into the armpits, palms, or forehead to inactivate the nerves that trigger sweating. It prevents sweating for about 5 months depending on the dose. These injections are effective but can cause muscle weakness and headache and are expensive. Because the Food and Drug Administration (FDA) has approved botulinum toxin type A only for excessively sweaty armpits, its use at other sites may not be covered by insurance.
If other treatments are not effective, various surgical procedures to control severe sweating may be tried. Excessive sweating limited to the armpits is sometimes treated by removing the sweat glands via surgery or liposuction. Excessive sweating limited to the palms can be treated by a procedure called endoscopic transthoracic sympathectomy, in which the nerves leading to the sweat glands are cut. However, surgery can cause permanent complications such as phantom sweating (a sensation of sweating, but no sweat exists), compensatory sweating (increased sweating in untreated parts of the body), gustatory sweating, nerve pain, and Horner syndrome. Compensatory hyperhidrosis is most common after endoscopic transthoracic sympathectomy, develops in up to 80% of people, and can be disabling and far worse than the original problem.
Body odor (bromhidrosis) can be treated by cleansing twice daily with soap and water or, if this is ineffective, with other measures used to treat bromhidrosis.