Probably the most common rash present in adults is seborrheic dermatitis. This disease typically affects the skin of the scalp, ears, forehead, face, and occasionally the mid-chest and/or back. When the scalp is involved, the red scaling plaques produce excess dandruff. Even though this condition is exceedingly common, there is a poor understanding of its cause. Although it is incurable, it is easily treatable with a variety of safe and effective topical medications, including topical steroids, zinc pyrithione, selenium sulfide, topical antifungals, and tar preparations found in medicated shampoos.