Seborrheic dermatitis is an inflammation of the upper layers of the skin. It typically causes a scaly, itchy rash that often appears with reddened skin on the scalp, sides of the nose, eyebrows, eyelids, skin behind the ears and middle of the chest. It may also appear on the navel, buttocks and skin folds under the arms, breasts and groin.

Seborrheic dermatitis results from an overproduction of skin cells and sebum, the skin’s natural oil. There are three age groups that are most likely to develop seborrheic dermatitis: infants, middle-aged adults and the elderly. When the disorder appears on the scalp in infants, it is called cradle cap.