Dry skin

Dry skin or xerosis is a common feature of skin disease, which reflects disruption to the skin barrier and the undue loss of moisture from the skin tissue. A list of common disease- or treatmentrelated causes of dry skin is given below:

• Atopic eczema
• Ichthyoses (inherited)
• Psoriasis
• Leprosy
• Drug induced (e.g. clofazimine given for leprosy)
• Phototherapy induced (e.g. PUVA therapy)

Disease processes lead to water loss because pathological or pharmacological effects will often disrupt the structure and processes that maintain the skin barrier integrity and retaining water within the dermis leading to transepidermal water loss (TEWL) and dehydration of the skin. Skin dryness may greatly vary in severity. It may occur without disease through factors such as over-washing of the skin or exposure to harsh climatic conditions. Because of severe environmental conditions or the presence of dermatological disease such as eczema or ichthyosis, the skin barrier will be impaired which will lead to dehydration of the skin by evaporation, develops cracking and fissuring of the skin, which will in turn further impair the integrity and effectiveness of the skin barrier.

Other external and intrinsic factors that cause dry skin and affect the skin barrier includes the following:

• Unsuitable skin hygiene, such as excessive washing, use of soap, water saturation due to undue soaking of the skin, rough skin drying technique, excessive routine skin washing and lack of moisturisation;
• Environmental factors both at home and externally including excessive UV exposure, centrally heated low humidity environments and use of air conditioning;
• Poor nutrition and inadequate hydration;
• Changes related to the maturity of the skin, with the risk of water loss from an immature infant’s skin – with its high surface area to volume ratio and water loss from aged skin due to age-related changes in skin structure, such as the loss of sebum (see Biology of the skin).