A diaper rash is an area of inflamed skin found in the diaper area in infants and young children. It is usually caused by skin irritation from prolonged contact with urine and feces.
A diaper rash can sometimes lead to a bacterial or fungal infection. Diapers, whether reusable or disposable, create a hot moist environment that traps diaper contents (e.g., urine and feces) against the skin, which causes irritation and can promote infection.
Most babies will have a diaper rash at some point. Although the number of severe diaper rash cases has decreased over time, diaper rash is just as common now as it was 30 years ago.