Xerosis (also called dry skin, asteatosis, or ashy skin) refers to a condition of rough, dry skin texture with associated fine scales. Xerosis is often pruritic. The pathogenesis involves a decrease in the amount of lipids in the stratum corneum and a deficiency in the water-binding capacity of this layer.

Xerosis is associated with a number of environmental factors and/or disease states, such as low humidity, frequent bathing, harsh soaps, ichthyoses, atopic dermatitis, hypothyroidism, Down syndrome, renal failure, malnutrition and malabsorptive states, human immunodeficiency virus disease, lymphoma, liver disease, Sjögren syndrome, carcinomatosis, and certain drugs.

The incidence of xerosis increases with age; nearly all individuals over the age of 60 have some degree of xerosis.