A rash describes any discoloration of the skin caused by inflammation. A rash can be caused by any one of a number of diseases, but in most cases indicates some irritation of the skin, such as that caused by an allergic reaction. As Dr. House advises, most rashes can be treated successfully by keeping them dry if they are moist, and keeping them moist if they are dry.

Persistent rashes usually require the attention of a dermatologist, who usually can recommend a topical preparation to place on the skin to aid it's healing.

A rash that spreads rapidly is usually an indication of a serious condition. However, a large rash that appears suddenly, although it may require medical attention, usually is a less serious matter.

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