23 October 2026 · Nina Aramway
People & Culture · Grandmother of ten
Why Does My Baby Keep Getting Diaper Rash?
When a rash clears with cream and air and then turns up again ten days later, you're not dealing with a rash so much as with whatever keeps starting one, and the cream can't tell you what that is, which is what my second daughter rang me about last month at eleven at night, her youngest on his fourth round since August and the tube of zinc nearly flat.
She'd done everything the leaflets say. She changed him often, she let him lie on a towel with nothing on, she bought the good cream, and each time it cleared in three days and each time it came back, and what we worked out between us over the following week was that the cream had been doing its job all along and nobody had asked what was setting it off.
We went through it all in roughly the order a doctor would ask, and I'll give it to you the same way.
Medicine, his or yours
Antibiotics come first, and the AAP (the American Academy of Pediatrics) puts them first on its own list of reasons for a rash that won't stay away. They kill some of the friendly bacteria in the gut along with the ones causing the illness, which can bring on loose stools, and fast stools contain more digestive enzymes, which wear at skin far harder than urine does. They also let candida, the yeast that lives in every gut, grow without its usual competition, and a yeast rash pays no attention to barrier cream however much of it you use.
The part people miss is that it can be your antibiotic too. If you're breastfeeding and you've been on a course for a chest infection or a tooth, the AAP lists that as a possible cause of rash in the baby, and I've never once heard a doctor in a busy clinic ask a mother about her own prescriptions unless she brought them up herself. Bring them up.
Stools that changed
Anything that changes what comes out changes the skin it ends up on. A tummy bug with three days of diarrhoea will leave most babies sore, and starting solids does it more gently but for longer, since the stools change in how often they come and in what's in them all at once, and some babies who never had a mark through the milk months get their first proper rash the month the purées start. Teething gets blamed as well, and the AAP does mention all the extra saliva being swallowed, though I've never been sure how much of what my mother called teething rash was teething and how much was everything else that happens to a baby at seven months.
If it lines up with a new food, keep a note for a week of what went in and when the rash flared. It sounds like more bother than it is, and it's the only way I know of telling a pattern from coincidence.
A yeast or strep that was never cleared
This is the one that sends people round in circles. A yeast rash treated with ordinary barrier cream looks a little better, because anything looks better under a layer of zinc, and then it comes straight back, and it goes on doing that until it gets an antifungal. It's shiny and bright red with sharp edges. It's worst inside the groin creases, where an ordinary rash leaves the skin alone. There are often small spots scattered past the edge. Look inside the mouth too, since the same yeast can show up there as white patches on the gums or the insides of the cheeks, which is thrush, and a baby with both needs both treated. My eldest had it in her mouth and on her bottom at the same time and I treated the bottom for a fortnight before anybody looked in her mouth. Use the antifungal for as long as you were told to, and not just until the morning it looks better.
Bright red skin right around the bottom, without much anywhere else, can be strep, and yellow crusts or weeping spots can be staph, and neither of those gets better at home. The AAP is firm that you shouldn't reach for an over-the-counter antibiotic ointment either, because some of the ingredients make the irritation worse.
Telling one rash from another
Wipes, creams and the washing
True allergy is rare, but it happens, and the clue is a rash that turns up after every contact with one thing and covers exactly the area that thing touches, which for a wipe is everywhere it's wiped and for a diaper is often the line of the elastic. Fragrance and preservatives in wipes and creams are the usual culprits, and dyes or elastics in the diaper itself. The AAP suggests switching for two weeks to see, and I'd say switch one product at a time, because if you change the wipes and the cream and the diapers on the same Saturday and the rash clears, you've learned nothing you can use the next time it happens.
Water and a soft cloth are enough for a wet diaper anyway. If you use cloth diapers, rinse them twice and leave out the fabric softener, and the same goes for the vests and sleepsuits that touch the diaper area.
Too tight, too small, too long
A diaper fastened too tight keeps the wet pressed against the skin and rubs it with every kick, and the sign is red rings where the elastic was when you take it off, which in my experience means the baby grew into the next size a fortnight before anybody in the house noticed. Fasten it a little looser or go up a size. The long stretch overnight is the other one, eleven or twelve hours in a single diaper in a room where the air-con goes off at two, and a baby who's clear all day and red every morning is telling you where to look.
A more absorbent diaper helps, and the AAP says so, though it also says no study has shown one brand preventing rash better than another, and that includes the one this shop sells.
Mentioned above
How the cream goes on
Cream on damp skin seals the damp in, so pat dry and give it a minute of air first. If the paste is still clean at the next change, leave it there and add more on top, because scrubbing it all off every time takes the top of the skin with it, and the AAP says as much. My mother rubbed everything off with olive oil at every change and I did the same with my first, then stopped with my second, who had far fewer rashes, though she was also the calmer baby and the cooler summer, so I wouldn't put it all down to the oil.
Taking it to the doctor
A rash that keeps coming back is a reason on its own to have someone look at it, and you don't need to wait until it's bad. Go sooner if there's a fever, blisters, pus or crusting, if it hurts him to be touched, or if it's spreading past the diaper. Take a photo on the worst day, because it'll have calmed down by the time you reach the waiting room, and take the wipes packet with you, since the first thing a good doctor asks is what's touching the skin and it's easier to hand it over than to remember the brand at the counter.
Where this comes from
- American Academy of Pediatrics: Why Is My Baby Always Getting Diaper Rashes?
- American Academy of Pediatrics: Common Diaper Rashes and Treatments
- NHS: Nappy rash
This guide is general information, written to help you understand a topic and ask better questions. It is not medical advice and does not replace your own doctor, midwife or paediatrician. Anything that worries you about your baby belongs with them.