Baby Diaper Rash

What's Happening Under the Diaper?

The Many Causes of Diaper Rash

The many causes of diaper rash

The primary cause of diaper rash is prolonged and increased exposure to wetness/moisture to the skin. Other contributing factors to diaper rash are:

  • The closed environment created by the diaper
  • Chafing from friction or rubbing
  • Prolonged contact of the skin with urine, feces or both
Closed Environments with Contaminants on Baby Skin
Diaper Rash Cause: BacteriaDiaper Rash Cause: UrineDiaper Rash Cause: Feces

Closed environment created by the diaper

Diapers are usually snug fitting. This results in little air reaching baby’s diaper area, which causes baby’s skin to become warmer and moister and therefore have a higher pH (which is a measure of acidity vs. alkalinity) than elsewhere in the body. Excessive moisture in the skin makes it more easily penetrated by irritants and more vulnerable to swelling.


Friction can weaken the protective barrier of the skin. Moist skin is more vulnerable to friction than dry skin, making the diaper area particularly prone to this problem. Friction between the diaper and the skin, two areas of skin (such as in skin creases and folds), and constant wiping and cleaning in the diaper area can facilitate the penetration of irritating substances into the skin.

Contact with urine and feces

The enzymes in feces (protease and lipase) may irritate baby’s tender skin. In addition, feces contain organisms that can cause skin infection. Urine further irritates the diaper area. As urine breaks down, it releases ammonia. This causes the pH of the skin to rise (in other words, to become increasingly basic, or alkaline) and the enzymes from baby’s stool to become more active. This may result in tissue/skin damage and lead to diaper rash.

Diapering tips

Watch this video to get diapering tips to keep your baby’s skin dry and diaper rash free.

Baby Skin Versus Adult Skin

The differences between them cause different skin care problems and require different care.