What causes nappy rash?

Nappy rash is a skin inflammation. Most cases are due to a reaction of the skin to urine and poo. Babies have sensitive skin which is vulnerable to irritation.

Érythème fessier

© Dailyboth, CC0, via Wikimedia Commons

In addition, a germ called candida commonly thrives on the inflamed skin. (This is the germ that also causes the infection commonly known as le muguet which most often occurs in the bouche (oral thrush) or around the genital area.) Candida can cause a more inflamed rash which is a brighter or darker red. Sometimes the rash can also become infected with other types of germs called bacteria. This will also make the rash more red and sore.

Nappy rash candida

© Elaine C. Siegfried1,†* and Adelaide A. Hebert2,†, CC BY 4.0, via Wikimedia Commons

Nappy rash can occur or worsen when your baby is teething. It is unclear why teething can lead to nappy rash although it is thought that it is due to your baby producing more saliva. This changes the nature of the baby's poo, making it more likely to cause a reaction when it touches the skin.

Most nappy rashes are mild or moderate and are not serious. Occasionally, skin conditions such as eczéma, psoriasis, infections and some rare skin diseases cause unusual nappy rashes.

Leave the nappy off as much as possible

This allows fresh air to get to the skin. Obviously, you cannot leave the nappy off all the time. However, the more fresh air, the better. Try letting the baby lie without a nappy on a towel or disposable absorbent sheet for a period of time each day. However, do change the towel or sheet as soon as it becomes wet.

Change the nappy often

Ideally, change the nappy as soon as it is wet or soiled. The aim is to prevent your baby's skin being in contact with urine and poo (faeces) for long periods of time. This is especially important if your baby is teething and has offensive, runny poo.

Wipes are as effective as water

Studies have shown that using baby wipes has the same effect on your baby's skin as using cotton wool and water. However, it is best to use wipes which are free from fragrance or alcohol.

After washing, make sure the baby's bottom is properly dry

Do this before putting on a new nappy. Dry by patting, not by rubbing, with a towel.

Do not use powder such as talcum powder

This may irritate the skin. Also avoid soaps, bubble baths and lotions.

Use barrier creams or ointments

Available to buy from pharmacies, barrier creams or ointments may help to protect the skin from moisture. They literally form a barrier between your baby's skin and the poo or urine. Ideally, rub on a thin layer of barrier cream or ointment just before putting on each nappy. Do not apply too much, as this may reduce the 'breathability' of the nappy. The recommended ointments are:

• Zinc and castor oil ointment.

• Metanium®.

• White soft paraffin ointment.

• Bepanthem® ointment.

Don't use tight-fitting plastic pants over nappies

They keep in moisture and may make things worse.

The above measures are likely to clear a mild rash. If the rash becomes worse, a healthcare professional may advise using one of the following in addition to the above measures:

• A mild steroid cream or ointment such as l'hydrocortisone can be used to treat nappy rash. Steroids treat inflammation. Apply sparingly as often as prescribed (before using a barrier cream or ointment) for a few days until the rash has cleared. A steroid cream or ointment should not usually be used for more than seven days.

• Une crème antifongique which kills thrush (candida). This is typically applied 2-3 times a day. Unlike a steroid cream, continue to use an antifungal cream for 7-10 days after the rash has cleared, to make sure all the candidal germs have gone. If you are prescribed an antifungal cream, use this without a barrier cream. In this way you clear up the infection first. THEN use the barrier cream to help clear up the nappy rash.

• A combination cream containing an antifungal agent and a mild steroid is often given.

Sometimes the inflamed skin of a nappy rash becomes infected with other types of germs (bacteria). This may be suspected if the rash becomes worse, despite use of the above treatments. In these cases an antibiotic medicine may be needed.

Also, as mentioned, occasionally a nappy rash is due to an unusual or more serious skin condition. Therefore, if a nappy rash does not improve with the usual treatment described above then see your doctor.