The popular term for a group of spots or red, inflamed skin that is usually a symptom of an underlying condition or disorder. Often temporary, a rash is only rarely a sign of a serious problem.

A rash may occur on only one area of the skin, or it could cover almost all of the body. Also, a rash may or may not be itchy. Depending on how it looks, a rash may be described as:

• Blistering (raised oval or round collections of fluid within or beneath the outer layer of skin)
• Macular (flat spots)
• Nodular (small, firm, knotty rounded mass)
• Papular (small solid slightly raised areas)
• Pustular (pus-containing skin blister).

There are many theories as to the development of skin rashes, but experts are not completely clear what causes some of them. Generally a skin rash is an intermittent symptom, fading and reappearing. Rashes may accompany a...