The effects of washing (skin hygiene) practices on the skin

Despite the significant amount of time nurses spend washing patients, the effects of washing activities on skin barrier function have received limited scientific appraisal. The evidence we have is largely based on the literature reviews, drawn from clinical observation, supported by limited experimental (quasi) study evidence and expert panel sources (Ersser et al., 2005).

The use of very hot water may cause unnecessary drying of the skin by removing skin oils and accelerating water loss by evaporation (Gooch, 1989). As an emulsifying agent, soap acts by dispersing one liquid into another immiscible liquid and so it suspends the oil or debris in water, aiding rinsing. Sodium lauryl sulphate is one of the most common synthetic surfactants found in soaps and detergents (Kirsner and Froelich, 1998). It is also a potent skin irritant, especially after prolonged exposure (e.g. Held et al., 2001), which may bind to keratin and cause denaturation of cell membranes, leading to an irritant response. Surfactants can also cause allergic contact dermatitis, but due to the high intensity effect of many, it can be difficult to differentiate an allergic reaction from contact irritation during patch testing (Flyvholm, 1993). Non-ionic surfactant, such as propylene glycol, is the least irritating group of surfactants. Products such as baby shampoo contain low- irritant, amphoteric surfactants, such as cocoamido-propyl betaine (Kirsner and Froelich, 1998).

Other physico-chemical effects of soap may disrupt the delicate skin barrier. Washing with soap may remove the natural protective emollient sebum oil from the skin (Baillie and Arrowsmith, 2001). Soaps and some cleansers may also raise the alkalinity of the skin (Korting et al., 1987) and thereby negating the influence of the protective acid mantle (see Biology of the skin). They may also change the balance of resident flora on the skin, leading to the proliferation or reduction of counts of common bacteria such as Propionibacterium acnes or Staphylococcus aureus, respectively (Korting and Braun-Falco, 1996); this may enhance the risk of skin colonisation and possible infection by pathogenic microorganisms.

Skin that is not dried carefully after washing can cause maceration and undue cooling. The mechanical and chemical drying of the skin can adversely affect barrier function, although the literature on this subject is limited.