Determining diaper rash type

The lingering smell of urine or dried stool edges can be a red flag for the most obvious cause of diaper rash, but there are other contributors that may not be as immediately clear.

“The most common diaper rash you’re going to see is contact irritant, and that will mostly be on skin prominences,” said Bernard A. Cohen, MD, professor of dermatology and pediatrics at Johns Hopkins School of Medicine and director of the Johns Hopkins University Pediatric Dermatology and Cutaneous Laser Center as well as section editor of Dermcase in Contemporary Pediatrics.

Other conditions like yeast infections can also be a culprit of red angry skin under a diaper, but there are less common, he added.

Diaper rash that is caused by a contact irritant like urine or stool is an obvious choice because infants essentially live in their diapers. Frequent changes are key, but even infants who are changed often can be irritated by the humid conditions and friction that exist between their skin and a diaper.

Some of the telltale signs that a diaper rash isn’t as simple as it seems include a spread of the irritation from prominences into the folds of the skin in the groin area, Cohen explained.

Secondary infections from yeasts like candidiasis or bacteria like Staphylococcus and Streptococcus can also develop and these are more likely to settle into creases as well as affecting more prominent surfaces in the diapered area. Psoriasis can present in diaper creases, too, Cohen added.

Although these conditions are not as common as diaper rash, they aren’t really rare either. What parents and providers should watch for, he suggested, is a sign of problems in other systems of the body.

One example of this is acrodermatitis enteropathica, a rare manifestation of zinc deficiency or problems with zinc metabolism that can lead to intestinal problems and diarrhea. Cohen said sometimes diaper rashes that are recurrent or difficult to get rid of could be a sign of something more that should be investigated.

“Nutritional deficiency rashes tend to happen in areas of trauma. Kids who are not thriving or who are not gaining weight may get diarrhea from malabsorption,” he noted.

Similarly, if rashes take on a blistering appearance or have weeping pustules and even a fever, infections like herpes simplex or enterovirus may be to blame.

In many cases, pediatricians can diagnose topical condition in diaper areas by a simple visual assessment, but if more serious underlying conditions are suspected, cultures and blood work can provide additional evidence.