Nappy (diaper) rash is a red rash which occurs on the buttocks and perineum of infants who wear nappies. Most infants have mild nappy rash at times, especially if the stools are loose. Painful vesicles and small ulcers may develop if the nappy rash is severe. Secondary bacterial or fungal infection is common. Seborrhoeic dermatitis may also present in the nappy area as a nappy rash.

Nappy rash is usually caused by urine and stool in the nappy irritating the skin. The rash is worse on exposed parts of the skin while the creases are often protected.

Frequent nappy changes, together with a protective zinc cream or petroleum jelly (Vaseline), usually protects against nappy rash. The best treatment is to keep the skin dry by removing the nappy for a few days and allowing the infant to lie on an open clean nappy. Expose the buttocks to warm, dry air as often as possible. Linen or toweling nappies must be washed and well rinsed before use. Do not use plastic pants over nappies.

A rash in the nappy area can also be caused by a fungus (Candida). A fungal rash (candidiasis) is very red, often has small satellite spots, and is worse in the creases. Treat as for nappy rash but also cover the affected skin with mycostatin cream. In severe cases, oral mycostatin for a few days may also be needed to clear fungus from the stool. Any severe nappy rash that does not improve after 5 days treatment should be referred to a skin clinic.