Nappy rash, otherwise known as napkin or diaper rash, is a red rash, or sore area, that affects skin under or around a baby's nappy.

There may be a little redness, but the area may become very sore and red, with red spots, blisters and broken skin.

The cause of nappy rash is the skin being kept wet along with the chemical irritation of ammonia produced by stale urine. This has the effect of breaking down the protective barrier normally formed by the skin, causing redness and rawness (inflammation) and allowing germs of various types to attack.

The most common infection to complicate the ammonia-like irritation is thrush (candida). In this event, the rash often has clusters or red spots around the margins of the main red area. Other germs (bacteria) can also infect the area.

It follows that the longer wet or soiled nappies are left in contact with the baby's skin, the more likely nappy rash is to develop. Some babies' skin is, however, much more sensitive than others. The problem is probably worse with old fashioned terry towelling nappies, especially if worn with waterproof underpants. Modern disposable nappies, which are better at keeping the fluid away from the skin, are better in some respects.

Other Factors

If using terry nappies, the detergent or softener might remain in the towelling, even after a full wash cycle. (Try smelling and wringing them while still damp. Often bubbles still appear.) Babies with sensitive skin may react to even minute amounts of these chemicals, especially if they contain a "biological" additive.

Babies may react to the elastic at the waist and legs of disposable nappies, and also to other components, but this is only rarely a problem.

• When possible, leave the nappy off, allowing air to get to the skin.
• It may help to use a barrier cream at nappy changes.
• Some barrier creams have antiseptic properties, which can help to deal with any germs.
• Discuss an appropriate cream with your nurse, health visitor, pharmacist, or doctor.
• If the rash is not settling after a few days, or is very raw and the skin broken, discuss with your health visitor, nurse, or doctor. You may need other treatments, which more specifically deal with infection.

Persistent nappy rash problems can come as a result of sensitivity to agents used in washing towelling nappies, and it is worth avoiding anything containing biological ingredients and trying a double rinse cycle.

• Think of the nappy as a way of stopping bedding and clothes being wet or soiled, not as a means of allowing you maximum time between changes.
• Change the nappy when it is wet or soiled. It may be as often as hourly in new born babies.
• Change the nappy before putting baby down after a feed, or to sleep.
• If the nappy is soiled, use the nappy to remove the worst of it, then wash with warm water and a gentle soap, using cotton wool. Alternatively, use baby wipes.
• When possible, allow the baby to lie in a warm environment without a nappy for a while, before putting on another one.
• If your baby seems to have a generally sensitive skin, think again about what you can do to reduce contact with anything that might upset this, such as detergents and conditioners, soaps, certain elastics and fabrics etc. Also, it is worth drawing this to the attention of you doctor, especially if there are skin problems (such as eczema) in the family.