In rare cases, some people in the early stages of ketosis will experience a skin inflammation called prurigo pigmentosa, known in keto circles as “keto rash.” It is similar in appearance to eczema or dermatitis, with annoyingly itchy pink lesions appearing typically on the neck, torso, or armpits.
The direct cause of prurigo pigmentosa is still unknown. At times, it has been linked to allergies, diabetes, pregnancy, fasting, dieting, eating disorders, and changes in your gut bacteria. It also seems to be much more prevalent in Asian populations, particularly Japanese, though it is beginning to be reported elsewhere. While very uncomfortable, it is not a serious condition and does not require a doctor’s attention.
Tips for Dealing with the Keto Rash
One potential cause of prurigo pigmentosa is a skin reaction to ketones in your sweat — specifically acetone, a known irritant. If you are in ketosis while exercising, wearing tight fitting clothing, experiencing hot weather, or you have highly sensitive skin, this could trigger the inflammation.
The rash can be treated in by wearing loose-fitting clothing, reducing exercise, or herbal anti-inflammatory creams such as Traumeel. If the itching is tolerable, adding small amounts of carbs to your daily intake may reduce the amount of ketones in your sweat enough to prevent inflammation while keeping you in ketosis. Remember to keep an eye on your ketone levels: staying in ketosis gives your body has a chance to adjust. Your energy system will likely become more and more efficient, meaning fewer ketones ending up in your sweat. Adding too many carbs and exiting ketosis will prevent this adjustment from happening, resulting the same amount of ketones in your sweat when you re-enter ketosis.
Try adding avocados or starchy veggies like beets and butternut squash. Sweet potatoes are fine when used sparingly — though be careful to avoid white potatoes as they are highly glycemic, resulting in extreme insulin responses.
If you are suffering from a particularly bad case of prurigo pigmentosa, you can add fruit to your diet. The sugar in fruit will have a big impact on your ketone levels, potentially even kicking you out of ketosis completely. Even just half a cup of blueberries could do the trick, but use more if necessary.
Blood Ketone Measuring
Careful and deliberate measurement of your ketones while adding carbs to your diet will help you monitor the effect on your inflammation. We recommend keeping yourself around a level of 1.5mmol/L, which is the low end of weight-loss ketosis. You can read more about degrees of ketosis here.
If you aren’t already using a blood meter, consider switching. Blood meters are much more accurate than urine strips or breathalyzers and will help you monitor your ketone levels as you adjust your diet. This kit, available on Amazon, has everything you would need to get started.
Remember to measure your blood ketones daily and add small amounts of carbs to track the change. If the problem persists, seek the opinion of a dermatologist.