For the episode, see The Itch.
An itch is an unpleasant sensation on the skin that encourages scratching. It is usually caused by irritation and inflammation at the site of the itch, often from an allergic reaction. Unlike pain, itching does not result in a withdrawal or guarding reflex. However, an itch does not necessarily indicate an issue at the site of the itch and may instead be a symptom of issue with the central nervous system, such as a brain tumor, multiple sclerosis or peripheral neuropathy. It is occasionally a sign of narcotic abuse, and can also be caused by mental illness.