T he skin provides an effective barrier against the external environment, preventing desiccation of the body through moisture loss (Madison, 2003), permeation of exogenous substances and infection. This barrier function is predominantly achieved by the upper layer of the skin, the epidermis, and in particular the outermost layer, the stratum corneum (Voegeli, 2012) (Figure 1). Within the stratum corneum the skin cells (corneocytes) are arranged in a 'brick wall' structure, held together by lipids. Normal skin has a pH of 4.5-6.2, creating an acid mantle that also contributes to the barrier function against bacteria and other irritants (Holroyd and Graham, 2014). When the skin is damaged, its barrier functions are lost. This article describes the pathophysiology of moisture-associated skin damage and incontinence-associated dermatitis (IAD) in particular. Regimens for prevention and treatment of IAD are discussed and the evidence for, and appropriate use of, barrier creams is presented, with a focus on Medihoney® Barrier Cream.