"While this condition has traditionally been considered rare, reports of prurigo pigmentosa are popping up with increasing popularity and adoption of the ketogenic diet," registered nutritionist Molly Knudsen, M.S., RDN, told mbg.
A study from Malaysia analyzed adults with prurigo pigmentosa and found that five of the nine participants were on a keto diet. A slightly older 2011 study had similar results, where 6 of the 16 participants who followed a keto diet later developed the skin condition.
The exact cause of the keto rash is unknown, but it's more common in women, says Sara Gottfried, M.D., integrative medicine physician and New York Times best-selling author.
Research has shown that certain irritants such as sweating, rubbing clothes, rubbing, or contact dermatitis can lead to PP, as well as metabolic associations due to diabetes mellitus, fasting, diet and excessive ketone levels in the body.
"This is a rare occurrence, but it can happen when you initially go keto," says Blevins. "If it does happen, it will usually appear within the first two weeks of starting the ketogenic diet," she adds.