A rash involves a change of the skin which affects its color, appearance or texture. It can be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, chapped, dry, cracked or blistered and may swell or become painful. The causes, and therefore treatments for rashes, vary widely. It is important to see your dermatologist for the correct diagnosis and treatment of any rash.