Diaper rash is any skin rash on the area covered by a diaper.
It is usually caused by prolonged contact of moisture, bacteria and ammonia with the skin. Nearly all children will get diaper rashes. With proper treatment, rashes usually go away in two to three days. Diaper rash can also be caused by a yeast infection. The rash of a yeast infection is usually bright red and raw, covers a large area, is surrounded by red dots and does not get better with initial treatments.