Diaper rash is a common skin irritation of early childhood. When skin remains wet for too long, it begins to break down. Moisture from a diaper can harm your baby's skin and make it more prone to chafing. When this happens a diaper rash may develop. Other causes of diaper rash include introducing new foods, using new brands of diapers, wipes, laundry detergent, etc., or using antibiotics.