Rash: Breaking out (eruption) of the skin. A rash can be caused by an underlying medical condition, hormonal cycles, allergies, or contact with irritating substances. Treatment depends on the underlying cause of the rash. Medically, a rash is referred to as an exanthem.
Quick GuideRosacea, Acne, Shingles: Common Adult Skin Diseases
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Last Editorial Review: 5/13/2016