Seborrheic dermatitis is a common skin disease that causes a red, scaly, itchy rash. Most often it occurs on the scalp, sides of the nose, eyebrows, ears, eyelids, and middle of the chest. This skin problem is easily treated, but chronic and recurring. Sometimes people use the terms dandruff, seborrhea, and seborrheic dermatitis to mean the same thing. However, these 3 terms differ. Dandruff causes scaling on the scalp but not redness. With seborrhea, the skin oily, mainly on the scalp and face, but has no redness or scaling. People with seborrhea may later get seborrheic dermatitis, which causes both redness and scaling. Seborrheic dermatitis affects people of all ages most often, though, in infant and older adults. In infants, the condition appears on the scalp (“cradle cap”). This mostly clears without treatment between 8 and 12 months of age. It is not contagious. In teens and adults, it tends to come and go and can be life-long. Elderly adults are prone to getting seborrheic dermatitis because of the effects of aging on the skin. The presence of a yeast(fungal)-like organism, excessive release of oil from the skin and immune system, all play a part in causing seborrheic dermatitis. Excess oil from the skin acts as food source for the yeast, which in turn causes inflammation (redness and swelling), irritation, scaling, and flaking.