Diaper Rash Causes

Diapers were a wonderful invention, controlling infants' waste products in a relatively convenient, clean, and healthy way. Still, ever since children began to wear diapers, diaper rash has been the most common skin disorder of infancy.

Skin wetness is the common denominator underlying the various causes of diaper rash. Urinary wetness increases skin friction, raises the skin pH, makes the skin less cohesive, and makes it more permeable. These effects combine to intensify the action of stool enzymes or other irritants that then inflame the skin.

A surprising number of different entities fall under the label of diaper rash.

This is the most common form of baby diaper rash, and affects almost all babies at some time. It's common on areas where friction is most pronounced; such as the inner thighs; or under the elastic of diapers that are too tight. It comes and goes quickly, and responds well to frequent diaper changes, airing out, and protective barriers.

This is most conspicuous on the exposed areas, such as the round part of the buttocks. It tends to not appear in skin folds and creases. It's generally the result of contact with stool enzymes or irritants such as harsh soaps, baby wipes, detergents, or topical medicines.

This might occur in combination with an irritant rash or by itself. It's also more common on exposed areas. The rash looks like poison oak.

Moist heat causes this common type of baby diaper rash that occurs deep in the skin folds. The skin looks thin, as if it has lost several layers.

Salmon-color, greasy skin with yellowish scales characterizes this diaper rash that's also worse in the skin folds.

This stubborn rash doesn't necessarily look distinctive. Other signs of psoriasis usually accompany the diaper rash, though, such as pitting of the nails or dark red areas with sharp borders and fine silvery scales on the trunk, face, or scalp.

A number of rare diseases such as congenital syphilis, histiocytosis X, zinc deficiency, Wiscott-Aldrich syndrome, acrodermatitis enteropathica, or Jacquet's dermatitis all cause characteristic diaper rashes. These are extremely uncommon but should be considered in prolonged, severe rashes that are unresponsive to the appropriate therapy.

In all the baby diaper rashes, the outermost layer of skin -- stratum corneum -- has been damaged. With this protective layer breached, it's easy for microorganisms such as yeast or bacteria to invade the inflamed skin. This makes the rash worse and less responsive to usual treatments.

Yeast is by far the most common type of organism found in a diaper rash. The organism is quite prevalent and thrives on warm, moist skin. Yeast involvement should be suspected in any diaper rash that hasn't improved dramatically with 72 hours of appropriate therapy. Current or recent antibiotic use makes a yeast infection even more likely, since this reduces the amount of the skin's "good" bacteria that fight infection. A classic yeast rash is beefy red with sharp raised borders and white scales. Small satellite lesions surround the main rash. Even without the classic pattern, however, yeast is often present.

Updated 2010.