The condition is slightly worse in males. The usual onset occurs with puberty. It peaks at age 40 years and is less severe, but present, among older people. In the infant it is seen as cradle cap or uncommonly as a flexural eruption or erythroderma. Intermittent active phases present with burning, scaling and itching, alternating with inactive periods.
Increased activity is seen in winter and early spring, with summer remissions common.
Active phases may be complicated by secondary infection in the intertriginous areas and on the eyelids. Such children may be suffering from a diaper dermatitis variant of seborrheic dermatitis or psoriasis. Generalized seborrheic erythroderma is rare. It is more often seen in AIDS, CHF, Parkinson disease, and in immunocompromised premature infants. Plaques are rare.