“Although this condition is traditionally considered rare, prurigo pigmentosa reports are emerging more with the growing popularity and implementation of the ketogenic diet,” registered dietitian Molly Knudsen, M.S., RDN, tells mbg.
One study from Malaysia analyzed adults with prurigo pigmentosa and found five of the nine participants were following a keto diet. A slightly older study from 2011 had similar results, in which 6 of the 16 participants who followed a keto diet later developed the skin condition.
The exact cause of keto rash is unknown but tends to be more common in women, says Sara Gottfried, M.D., integrative medicine doctor and New York Times best selling author.
According to research, certain irritants like sweating, clothing friction, rubbing, or contact dermatitis can lead to PP, as well as metabolic associations from diabetes mellitus, fasting, dieting, and excess levels of ketones in the body.
“This is a rare occurrence, but can happen when one initially goes keto,” Blevins says. “If it happens, it will typically occur within the first two weeks of starting the ketogenic diet,” she adds.