Nappy rash is very common but it can still be a shock when you take off your baby’s nappy to discover red, raw-looking skin. But what causes it? Contrary to popular belief, it’s not wee that causes it – it’s poo. “Although a baby who’s been sitting in a wet nappy for too long is likely to get nappy rash, this is not the main reason it starts,” says Stephen Kownacki, chair of the Primary Care Dermatology Society. “It happens mainly because a baby’s poo contains digesting enzymes, which can start breaking her skin down if she’s left sitting in a dirty nappy too long. But nappy rash can also be aggravated by ammonia, which is made when your baby’s wee is broken down by bacteria from her poo, and in turn irritates her skin.”

There’s great debate about whether teething causes ‘runny nappies’ and in turn nappy rash, with many experts saying it’s a myth. But Dr Tabi Leslie insists that it’s true. “When your baby is teething, she’ll dribble more,” she explains, “so she’s likely to swallow a lot more saliva than normal. As this passes through her stomach, more stomach acid is produced and her poos will become runnier and more likely to cause a reaction.”

So what can you do, to tackle nappy rash, once it’s appeared? Change nappies regularly and stop using wipes advises Stephen. “It’s not a good idea to use baby wipes when she has nappy rash as some contain additives like antiseptics, which will aggravate the rash further,” he says. The best thing you can use is cotton wool and water – but there are some sensitive skin wipes which might be gentle enough.

Fresh air is the best thing for nappy rash, so allow your baby to go nappy free for a while (doing this straight after a poo or wee will minimise the chances of an accident on your carpet!). Or go outside to the garden and let your baby play nappy-free.

Bath your baby every day, to keep the area clean, but don’t use any bubble bath or shampoo, as this might irritate the skin. After the bath, pat the area dry (making sure it’s REALLY dry!) and then apply Love Boo Bottom Butter generously. It’s packed with some of nature’s kindest ingredients – cotton seed oil, Tahitian Monoi and lavender oil – which work to soothe the skin. It also works as a barrier against future irritation.

If it looks like it’s getting worse, go and see your GP for advice.