Diaper rash is very common. About half of all babies get it at some point. And it’s usually found in newborns and infants, but it can also be seen in diaper wearing adults. It’s more likely to occur when there is a change in diet. This often happens after infants, say, start eating their solid foods, for example. If they’re on antibiotics for something like an ear infection, it can cause loose stools, because it kills the natural flora in the gut that helps with digestion, and this can lead to diaper rash.