Dry skin, also known as Xerosis, is common. It can occur at any age and for many reasons. Using a moisturizer often helps repair dry skin. Extremely dry skin can be a warning sign of a skin problem called dermatitis. Dermatitis means inflammation of the skin. It can cause an itchy rash or patches of dry irritated skin. The earlier dermatitis is diagnosed and treated the better. Without treatment, dermatitis often gets worse.