Perspiration is the process of fluid removal through sweat glands in the skin. It occurs in response to heat, strenuous exercise or emotional stress. Both the process and the fluid can be called perspiration. It occurs in millions of sweat glands located near the skin surface over almost all of the body. Sweat is carried to the surface of skin by tiny ducts that attach to the pores (tiny holes in the skin).

Sweating is the body’s natural way of regulating its internal temperature. Perspiration is a natural response to feeling hot. When sweat evaporates on the surface of the skin, it removes excess heat and has a cooling effect on the body. Perspiration also removes small amounts of waste products from the body.

A number of factors (e.g., food, medications, illnesses) can affect how much a person sweats and even the way the sweat smells. Sometimes these factors may cause either excessive perspiration (hyperhidrosis) or little or no perspiration (anhidrosis).

Except for causing embarrassment, hyperhidrosis is generally not serious. However, in some circumstances it may be a sign of an underlying health disorder, especially if accompanied by fever.

Anhidrosis can be potentially life threatening. If the body is unable to cool itself naturally by sweating, it can lead to hyperthermia (overheating). If body temperature continues to rise, heatstroke (a severe condition that can lead to shock, brain damage, organ failure and even death) can occur.