Diaper (napkin) dermatitis is an acutely presenting inflammatory irritant contact dermatitis of the diaper region. It is one of the most common dermatologic diseases in infants and children. In the past, the disease was thought to be caused by ammonia; however, a number of factors, such as friction, wetness, inappropriate skin care, microorganisms, antibiotics, and nutritional defects, are important. Diaper dermatitis commonly affects the lower parts of the abdomen, thighs, and diaper area. Involvement of skin fold regions is typical with diaper dermatitis. At the early stages of the disease, only dryness is observed in the affected area. At later stages, erythematous maceration and edema can be seen. Secondary candidal and bacterial infections can complicate the dermatitis. In the differential diagnosis of the disease, allergic contact dermatitis, intertrigo, psoriasis, atopic and seborrheic dermatitis, and the other diseases should be considered. Causes of the disease should be determined and eliminated primarily. Families need to be informed about the importance of a clean, dry diaper area and the frequency of diaper changes. The use of superabsorbent disposable diapers has decreased the incidence of the disease. Soap and alcohol-containing products should be avoided in cleaning the area. In some cases, corticosteroids and antifungal agents can be administered. If necessary, antibacterial agents and calcineurin inhibitors can also be beneficial. (C) 2015 Elsevier Inc. All rights reserved.