By Dr. Catherine Gant

Nappy rash is irritation or infection of the skin in the nappy area. It can be caused by chemical irritation (ammoniacal dermatitis) from wet nappies, or infection (e.g. thrush)

CLINICAL SIGNS

Ammoniacal dermatitis is a chemical burn to the skin, which occurs when bacteria convert the urine to ammonia. This happens when wet nappies are allowed to stay in contact with the baby’s skin for too long. It is caused by not changing the nappy frequently enough when wet, and is often worse when cloth nappies are used. The skin is red, and the skin creases at the top of the legs are classically spared, as the skin deep in the creases is not in contact with the wet nappy. A similar picture is seen with nappy rash caused by diarrhoea.

Allergy to nappies impregnated with lotion, wipes, or cream may also cause a nappy rash, and the skin creases are often spared with the rash confined to the area where the nappy touches the skin. To see a picture, go to New Zealand DermNet, and click on napkin dermatitis in the 'Skin Conditions' section.

Thrush (Candida) can infect the nappy area. It is commonly found in the mouth at the same time (oral thrush), especially in breast fed babies, as white patches on the lining of the cheeks in the mouth. See a picture of severe oral thrush at Dr. Fungus - Image Bank – (search for candidiasis in the human disease box). The nappy rash has white flaky patches and the skin creases are also affected. You sometimes see small satellite patches of infection outside the nappy area, like little spots spreading up over the abdomen.

Eczema - usually affects other areas as well.

Bacterial infection - if the skin is broken, a bacterial infection may develop - the skin feels red and hot, and may be swollen. There may be discharge and the baby may develop a fever and stop feeding.

TREATMENT

Ammoniacal Dermatitis

This is treated by exposing the affected area to fresh air whenever possible. Clean the skin with water and cotton wool - not wipes, which will sting the baby. Change nappies frequently, and use a good barrier cream.

Thrush

This is treated with an anti-fungal cream, and it is often worth treating the mouth for oral thrush as well, and treating nipples if the baby is breast-fed. See oral thrush in the newborn in our health A-Z section.

Eczema and Diarrhoea

Treat the underlying problem, and with diarrhoea change the nappy as soon as it is dirty and use loads of barrier cream.

Bacterial Infections

These are characterised by a worsening of the symptoms. Your doctor will probably prescribe an antibiotic cream, or in severe skin infections antibiotics by mouth, but good skin-care is still important.