Nappy rash - causes

The simplest cause of nappy rash is prolonged exposure to wetness from urine or stools. Both are responsible for increasing the skin PH and for promoting the activity of faecal enzimes. The result is the breakdown of the outermost layer of the skin, which in a baby is still very thin, and so the area becomes red or sore.
Once damage occurs, the skin can become susseptable to germs resulting in a rash with secondary infection.
Diet is another possible cause of nappy rash. Breastfed babies, for example, have a lower incidence of nappy rash, because their stools have lower pH and lower enzymatic activity. An increased likelihood of nappy rash occurs when a baby's diet undergoes a significant change (i.e. from breast milk to formula or from milk to solids). Treatmemt with antibiotics, or detergents remaining in the nappies are other frequent causes. Babies with sensitive skin may even react to minute particules of these chemicals, especially if they contain a "biological" additive.