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Excessive sweating is difficult to measure. It is usually noticed by a person or by the healthcare professional.

What is going on in the body?

The main purpose of sweating in the body is to get rid of excess body heat. Sweat on the skin evaporates, and this cools the body. Excessive sweating can sometimes be a sign of serious underlying conditions.

Sometimes excess sweating is the result of a hereditary condition called hyperhidrosis, characterized mainly by flushing and sweaty palms. In this condition, sweating is usually worse during times of emotional stimulation.

What are the signs and symptoms of the condition?

One expects to sweat a lot after strenuous exercise or when the weather is very hot. When someone has an abnormal amount of sweating that is not related to exercise or the weather, he or she should see a healthcare professional, who needs to ask questions including:

• How long has the sweating been going on?
• When does the sweating occur? All day, or only at night?
• Is there a fever? Does the person feel sick?
• Is there a family history of excessive sweating?
• Is the person taking any medications or illegal drugs?
• Does the sweating occur in only some areas of the body or all over?

Any other symptoms may be important as well. For example, unintended weight loss, headaches, cough, or chest pain are important symptoms that may point to a certain cause for the sweating.

What are the causes and risks of the condition?

Excessive sweating has many causes, including:

• hyperhidrosis
• strenuous activity
• hot weather or wearing too much clothing for the temperature
• inherited factors, as some people sweat more than others
• migraine headaches
• almost any infection, such as pneumonia, tuberculosis or a serious heart infection called endocarditis
• hyperthyroidism, an increased level of thyroid hormone in the body
• pain, stress, anxiety or fear
• hypoglycemia, that is, low blood sugar
• serious heart conditions, such as a heart attack or congestive heart failure
• serious lung conditions, such as emphysema, pulmonary edema or a pulmonary embolus
• medications, such as haloperidol, which is used to treat psychosis
• illegal drugs, such as cocaine
• cancer or other tumors
• autoimmune disorders, in which a person's immune system attacks the body. Some examples are rheumatoid arthritis and systemic lupus erythematosus.
• strokes, which can affect the temperature control center of the brain

Other causes are also possible. In some cases, no cause can be found.

What can be done to prevent the condition?

Prevention is related to the cause. For example, excessive sweating due to exercise or hot weather can be avoided by avoiding activity or using air conditioning. Low blood sugar can often be avoided by getting enough to eat and taking medications for diabetes as directed. Many cases of excessive sweating, including hyperhidrosis, cannot be prevented.

How is the condition diagnosed?

In some cases, the cause of excessive sweating is obvious to the healthcare professional from the history and physical exam. In other cases, further testing may be needed. For example, thyroid function tests can detect increased thyroid hormone levels and a fasting blood glucose test can detect low blood sugar. A chest x-ray can often help diagnose pneumonia or tuberculosis. A special type of x-ray, called a cranial CT scan, can help diagnose a stroke. Other tests may be needed in some cases.

What are the long-term effects of the condition?

Excessive sweating can lead to dehydration and salt imbalances in the body. Other long-term effects are related to the cause. For example, a stroke can leave a person paralyzed or unable to talk. Infections often go away on their own or after treatment with antibiotics and may have no long-term effects.

What are the risks to others?

Excessive sweating itself is not contagious and poses no risk to others. If the cause of the sweating is an infection, the infection can be contagious.

What are the treatments for the condition?

People need to increase their fluid and salt intake when they have excessive sweating. The fluid and salt may need to be given intravenously in severe cases or if persons cannot drink fluids on their own.

• Persons with infections may need antibiotics.
• Persons with high thyroid hormone levels may need medication to control their thyroid levels.
• Persons with cancer may need surgery, chemotherapy, or radiation therapy.
• Persons who have had a stroke may need physical therapy to be able to walk or talk again.

Hyperhidrosis can be treated with medications, or in more severe cases, it is treated by a surgical procedure known as endoscopic transthoracic sympathectomy, in which sympathetic nerves in the chest responsible for the symptoms are cut or blocked. The surgery is usually curative.

What are the side effects of the treatments?

Side effects depend on the treatments used. Each medication has its own array of possible side effects. For example, antibiotics may cause allergic reactions and stomach upset. Surgery can be complicated by bleeding, infection, or reactions to anesthesia.

What happens after treatment for the condition?

What happens after treatment depends on what is causing the excessive sweating. If the cause is "fixed" or reversed, no further treatment may be needed. This often occurs after an infection, such as pneumonia, is treated with antibiotics. People who have had a stroke may need lifelong medical and nursing care. Those with cancer may die if treatment is unsuccessful.

How is the condition monitored?

The person can monitor their sweating at home. Other monitoring depends on the cause. For example, those with a heart attack may need close monitoring in the intensive care unit for several days.