Night Sweats

Doctors in primary care fields of medicine often hear their patients complain of night sweats. Night sweats refer to any excess sweating occurring during the night. However, if your bedroom is unusually hot or you are using too many bedclothes, you may begin to sweat during sleep - and this is normal. In order to distinguish night sweats that arise from medical causes from those that occur because one’s surroundings are too warm, doctors generally refer to true night sweats as severe hot flashes occurring at night that can drench sleepwear and sheets, which are not related to an overheated environment.

In one study of 2267 patients visiting a primary care physician, 41% reported experiencing night sweats during the previous month, so the perception of excessive sweating at night is fairly common. It is important to note that flushing (a warmth and redness of the face or trunk) may also be hard to distinguish from true night sweats.

There are many different causes of night sweats. To determine what is causing night sweats in a particular patient, a doctor must obtain a detailed medical history and order tests to decide if an underlying medical condition is responsible for the night sweats.

The following are some of the known conditions that can cause night sweats :

Menopause

The hot flashes that accompany the menopausal transition can occur at night and cause sweating. This is a very common cause of night sweats in perimenopausal women.

Idiopathic hyperhidrosis

Idiopathic hyperhidrosis is a condition in which the body chronically produces too much sweat without any identifiable medical cause.

Infections

Classically, tuberculosis is the infection most commonly associated with night sweats. However, bacterial infections, such as the following conditions can also be associated with night sweats:

√ endocarditis (inflammation of the heart valves),
√ osteomyelitis (inflammation within the bones due to infection),
√ abscesses (for example, boils, appendix, tonsils, perianal, peritonsillar, diverticulitis),
√ AIDS virus (HIV) infection.

Night sweats are an early symptom of some cancers. The most common type of cancer associated with night sweats is lymphoma. However, people who have an undiagnosed cancer frequently have other symptoms as well, such as unexplained weight loss and fever.

Taking certain medications can lead to night sweats. In cases without other physical symptoms or signs of tumor or infection, medications are often determined to be the cause of night sweats.

Antidepressant medications are a common type of medication that can lead to night sweats. All types of antidepressants can cause night sweats as a side effect, with a range in incidence from 8% to 22% of persons taking antidepressant drugs. Other psychiatric drugs have also been associated with night sweats.

Medicine taken to lower fever such as aspirin and acetaminophen can sometimes lead to sweating.

Other types of drugs can cause flushing (redness of the skin, typically over the cheeks and neck), which, as mentioned above, may be confused with night sweats. Some of the many drugs that can cause flushing include:

√ niacin [(Niacor, Niaspan, Slo-Niacin) (taken in the higher doses used for lipid disorders)],
√ tamoxifen (Nolvadex),
√ hydralazine,
√ nitroglycerine,
√ sildenafil (Viagra).

Many other drugs not mentioned above, including cortisone, prednisone, and prednisolone, may also be associated with flushing or night sweats.

Sometimes low blood glucose (hypoglycemia) can cause sweating. People who are taking insulin or oral anti-diabetic medications may experience hypoglycemia at night that is accompanied by sweating.

Sweating or flushing can be seen with several hormone disorders, including pheochromocytoma, carcinoid syndrome, and hyperthyroidism.

Uncommonly, neurologic conditions may cause increased sweating and possibly lead to night sweats including:

√ autonomic dysreflexia,
√ post-traumatic syringomyelia,
√ stroke,
√ autonomic neuropathy.



Reference: Mold, JW, Mathew, MK, Belgore, S, DeHaven, M. Prevalence of night sweats in primary care patients: an OKPRN and TAFP-Net collaborative study. J Fam Pract 2002; 51:452.