When the stratum corneum becomes dehydrated it loses its flexibility and becomes dry, cracked, scaly and sometimes itchy. The stratum corneum contains natural water-holding substances, including urea, which retain water from seeping out of the deeper layers of the skin. Water is normally retained in the stratum corneum by a surface film of sebum, which slows down the evaporation of water from the skin surface.

The skin dries out when too much water evaporates from the surface. This increases with age and is made worse by excessive washing because hot water and soap can remove the layer of natural oil on the skin surface. Dry skin can be present in several dermatological skin diseases including atopic dermatitis (eczema), ichtyosis and psoriasis. Treatments for dry skin

Emollients (in moisturizing lotions and creams) are the standard treatment for all dry and scaly skin conditions. They smooth, sooth and hydrate dry skin. Emollients need to be applied frequently to be effective. Not all emollients are the same. They contain a range of different ingredients, and some dry skin conditions respond better to some emollients than others.