Diaper rash (diaper dermatitis) is a skin irritation caused by prolonged skin wetness, friction with the diaper material, and contact with chemicals in the urine and stool. The skin may look red, raw, scalded, or burned. While a diaper rash is uncomfortable, normally it is not serious.

Diaper rash is the most common skin problem seen in babies and young children, but it can occur at any age if diapers or incontinence briefs are worn. The highest incidence of diaper rash is seen in babies between the ages of 9 and 12 months. It frequently occurs in babies who sleep for many hours without waking.

An adult may develop a rash in the genital area if he or she is unable to routinely wash the genital area, such as on a long backpacking trip, or does not have complete bowel or bladder control (incontinence).

The skin may blister or peel in severe cases of diaper rash, leaving raw areas that may bleed or ooze fluid. A diaper rash that becomes raw, oozes fluid, or bleeds is harder to treat. Fungal or bacterial infections may be the cause of a severe diaper rash.

The most common causes of diaper rash include:

Not changing a wet or dirty diaper often enough. The skin becomes irritated from contact with urine and stool, particularly when diarrhea is present.
Rubbing or irritation of the skin by a diaper or incontinence brief. The irritated area may include the thighs, genitals, buttocks, or belly area.
A skin reaction to perfumes in the disposable diapers or incontinence briefs, to chemicals in skin-cleaning diaper wipes, or to the detergents or fabric softeners used to clean cloth diapers.