Sweating is the release of liquid from the body's sweat glands. This liquid contains salt. This process is also called perspiration.

Sweating helps your body stay cool. Sweat is commonly found under the arms, on the feet, and on the palms of the hands.

Perspiration

The amount you sweat depends on how many sweat glands you have.

A person is born with about 2 to 4 million sweat glands, which begin to become fully active during puberty. Men's sweat glands tend to be more active.

Sweating is controlled by the autonomic nervous system. This is the part of the nervous system that is not under your control. Sweating is the body's natural way of regulating temperature.

Things that can make you sweat more include:

• Hot weather
• Exercise
• Situations that make you nervous, angry, embarrassed, or afraid

Heavy sweating may also be a symptom of menopause (also called a "hot flash").

Causes may include:

• Alcohol
• Caffeine
• Cancer
• Complex regional pain syndrome
• Emotional or stressful situations (anxiety)
• Essential hyperhidrosis
• Exercise
• Fever
• Infection
• Low blood sugar (hypoglycemia)
• Medicines, such as thyroid hormone, morphine, drugs to reduce fever, and medicines to treat mental disorders
• Menopause
• Spicy foods (known as "gustatory sweating")
• Warm temperatures
• Withdrawal from alcohol, sedatives, or narcotic painkillers

After sweating a lot, you should:

• Drink plenty of fluids (water, or fluids containing electrolytes such as sports drinks) to replace sweat.
• Lower room temperature a little bit to prevent more sweating.
• Wash your face and body if the salt from sweat has dried on your skin.

Contact your health care provider if sweating occurs with:

• Chest pain
• Fever
• Rapid, pounding heartbeat
• Shortness of breath
• Weight loss

These symptoms may indicate a problem, such as overactive thyroid or an infection.

Also call your provider if:

• You sweat a lot or sweating lasts for a long time or cannot be explained.
• Sweating occurs with or is followed by chest pain or pressure.
• You lose weight from sweating or often sweat during sleep.

Chelimsky T, Chelimsky G. Disorders of the autonomic nervous system. In: Daroff RB, Jankovic J, Mazziotta JC, Pomeroy SL, eds. Bradley's Neurology in Clinical Practice. 7th ed. Philadelphia, PA: Elsevier; 2016:chap 108.

Cheshire WP. Autonomic disorders and their management. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 418.

McGrath JA. The structure and function of skin. In: Calonje E, Bren T, Lazar AJ, Billings SD, eds. McKee's Pathology of the Skin. 5th ed. Philadelphia, PA: Elsevier; 2020:chap 1.