Cause of Night Sweats

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Cause of Night Sweats

Question:

What causes night sweats?

Answer:

Night sweats are often difficult to define and difficult to diagnose. We define night sweats as drenching sweats at night that make someone change their nightclothes or sheets. Of course, we don't count sweats caused by an overheated bedroom or too many blankets.

Night sweats may be difficult to distinguish from hot flashes that women experience around the time of menopause. People often use the same words to describe both. Hot flashes usually begin with an unpleasant sensation in the body, then a sudden warmth and skin redness.

Flushing, as seen with certain medications and certain illnesses, also tends to involve warmth and redness. Flushing is often present during the day as well as at night.

What are the common causes of night sweats? Doctors usually think of several categories of illnesses that can cause true night sweats.

These include:

• Malignant tumors. The most common tumors associated with drenching night sweats are lymphomas, including Hodgkin's disease. Other types of cancers have also been associated with night sweats.

• Infections, especially those that are chronic, such as tuberculosis. Occasionally night sweats are the only symptom of the infection for a long time. HIV/AIDS infection has also been associated with night sweats.

• Medications. Many medicines can give people night sweats. Common examples include antidepressant medicines, niacin, tamoxifen and insulin.

• Endocrine problem. Occasionally endocrine disorders are the cause of night sweats or flushing. Several different illnesses, including thyroid disorders, pheochromocytoma and carcinoid syndrome can lead to flushing or true night sweats.

Although the list of causes of night sweats is long, we do not actually know the underlying mechanisms of most night sweats. More research needs to be done. We also need more information on the mechanism of hot flashes. With better understanding of the underlying mechanism, better treatments might emerge.

Diana Post, M.D., is an assistant professor of medicine at Harvard Medical School and a member of the Department of Medicine at Brigham and Women's Hospital.

Last updated:	July 20, 2009