An abnormal lack of sweat in response to heat may be harmful, because sweating allows heat to be released from the body.

Anhidrosis sometimes goes unrecognized until a substantial amount of heat or exertion fails to cause sweating.

Overall lack of sweating can be life-threatening because the body will overheat. If the lack of sweating is localized (happening in a small area only), it is usually not as dangerous.

• Neurologic disorders such as Guillain-Barre syndrome
• Skin diseases that block sweat glands
• Congenital disorders including as ectodermal dysplasia
• Some drugs
• Trauma to sweat glands
• Burns
• Dehydration

If there is a danger of overheating, take a cool shower or sit in a cool bathtub and drink plenty of fluids. Remain in a cool environment. Move slowly during hot weather. Avoid heavy exercise and hot foods.

• There is generalized lack of sweating (home care should be used while waiting to see the doctor).
• There is any abnormal lack of sweating when exposed to heat or strenuous exercise.

The medical history will be obtained and a physical examination performed. In emergencies (where rapid cooling measures and fluid replacement will be initiated) the patient will be stabilized first.

Medical history questions documenting absent sweating in detail may include:

• When did this begin?
• Has it been present since infancy or childhood?
• Is it only on one side of the forehead?
• Is it on the whole body?
• What other symptoms are also present?

Diagnostic tests that may be performed include:

• Drugs administered to stimulate sweating
• Topical substance applied to the skin
• The person may be placed in a sweatbox for observation
• The person may be wrapped in an electric blanket to observe sweat patterns
• A skin biopsy may be performed