The short version
His skin reacted to one scented pack and settled with water and cotton. Dermatology guidance suggests fragrance-free, alcohol-free wipes or plain water; a label can't tell you which ingredient caused a reaction. The unscented 99% water wipes we switched to list no fragrance or MI.
What happened
The first wipes we used smelled like a hotel bathroom. That should have been the clue. By week eight he had a stubborn red rash around the nappy line that no cream shifted, and the paediatrician's first question was: "what wipes?"
I'd never read the back of the pack. When I did, I needed a chemistry degree. Alcohol, which dries and stings. "Parfum", a legal word for a mystery. And a preservative, methylisothiazolinone, that I later learned had its own paper in a paediatrics journal, describing children whose rashes cleared completely once the wipes were stopped.
We stopped. For a week it was cotton and warm water from a steel bowl, which is what every grandmother in the building had been telling me all along. The rash went. And then I went shopping with a rule, not a brand: no fragrance, no drying alcohol, no MI, as close to water as possible.
What I found is that the label on the front and the list on the back often disagree. A pack can say "gentle" and still contain perfume. One pack I nearly bought said "free from allergic fragrances" in big letters and "fragrance" in the ingredients in small ones. The ingredient list is the only part of the packet that's regulated.
The one we use now is Mother Sparsh's 99% water unscented wipes. Not the 98% version, which is mildly scented and contains perfume; the 99% unscented one, with no fragrance, no alcohol, no MI, and a thick plant-fibre sheet that doesn't shred. Three years on, two cousins and a neighbour use them too. But the rule came first, and if you find another pack that passes it, buy that.
A 2014 paper in Pediatrics described six children with chronic rashes who were patch-test positive to the preservative methylisothiazolinone (MI) in wet wipes; their rashes resolved quickly and completely once the wipes were stopped. A separate survey found MI in 14 of 39 baby wipes on US shelves, including some labelled sensitive or hypoallergenic.
Chang MW, Nakrani R, Pediatrics 2014. Summary · Schlichte MJ, Katta R, Dermatology Research and Practice 2014. SourceThe NHS and the American Academy of Dermatology give the same advice for cleaning the nappy area: plain water with a soft cloth, or wipes that are fragrance-free and alcohol-free.
NHS, Nappy rash. Source · AAD, How to treat diaper rash. SourceThe verdicts
Mother Sparsh 99% Pure Water Unscented wipes, 72 pulls
Passes the rule: no fragrance, no alcohol, no MI, and a thick sheet. The unscented 99% pack, not the scented 98% one.
Cotton rounds and a steel bowl of warm water
Free, perfect, and what fixed the rash. Our at-home default for the first three months.
Cubworthy, with a catch
Mother Sparsh 98% Water wipes (the standard pack)
Alcohol- and MI-free, but the ingredient list includes fragrance and it's described as mildly scented. Fine for hands and faces; for a baby who reacts, go unscented.
The scented wipes we stopped using
His skin reacted after one particular pack; I stopped it and the rash cleared with water and cotton. That tells me what happened at home, not which ingredient did it.
Product details are as we used them; the version on sale now may differ. Check the exact model and the manufacturer's instructions.