Prurigo pigmentosa (PP) – a.k.a. “keto rash” – is a rare but recognized phenomenon – one that may become less rare as more people begin to follow keto diets. (PP may also occur in some individuals with ketoacidosis and has been observed post-bariatric surgery as well. It has been reported more often in women and in people of Asian descent.) The precise cause of PP in conjunction with the state of ketosis is unknown but the authors of the newly published case study wrote, “…it is theorized that ketone bodies can induce neutrophil-mediated perivascular inflammation, a theory supported by the fact that PP responds well to medications that inhibit neutrophils, such as tetracyclines or dapsone.”
Physicians experienced in the ketogenic diet anecdotally report that PP often fades on its own over time, but it can also be treated with antibiotics. Most published reports of PP induced by keto diets recommend that affected individuals simply increase their carbohydrate intake, resulting in gradual disappearance of the rash. Owing to keto’s popularity on social media, many individuals may be restricting carbohydrates to an unnecessary degree and may be able to experience the metabolic benefits of a lower carbohydrate intake while keeping carbs adequate enough to prevent ketosis, which appears to be the triggering factor in the rash. Those who experience PP but require maintenance of a ketogenic state to prevent seizures or to support mental health stability can work with a professional to customize long-term treatment of the rash while following their therapeutic diet.