What causes the keto rash?

While the exact mechanism of development is largely unknown, growing bodies of evidence suggest there are some pretty likely connections.

Gut dysbiosis

Some studies suggest that an altered gut microbiome may be a contributing factor to the onset of PP. Gut dysbiosis resulting from nutritional and other environmental factors may alter the profile of the gut microbiota and unfavorably modify the body’s immune response. Gut dysbiosis can lead to the production of bacterial toxins, increased intestinal permeability, and contribute to systemic inflammation engendering skin conditions like acne[8], rosacea, and eczema.

Dietary changes

Recent dietary changes may be linked to the onset of PP. In a study analyzing 50 cases of PP[9], 17 patients underwent dietary changes prior to the development of the rash. The dietary modification is not specified, but changes may relate to the transition into a low-carb diet.

Ketonemia

In normal fasting, ketone bodies are produced and circulate in the blood in response to lower insulin and blood glucose levels. which causes the production of ketones for fuel. Ketonemia occurs when you have unusually high blood ketone levels. A 2015 study on PP[10], ketonemia and diabetes, found that ketones in the urine coincided with the onset of the PP eruption. As glucose and total ketone levels in blood decreased to within a normal range, the condition subsided. The blood ketones specifically had the greatest effect on the decrease of the eruption when compared with blood glucose. As such, it is likely that excess ketone bodies in the blood might be linked to the onset of prurigo pig­mentosa.

Another study[11] suggests that ketone bodies pass from blood circulation into tissues, enter cells, and reach the cytoplasm to be used directly in lipogenesis and to be oxidized by mitochondria. The surplus of ketone bodies may collect around blood vessels and lead to an inflammatory reaction, which may be a trigger in the onset of PP.

Mechanical irritation

Some research has indicated the friction caused by clothing can contribute to the onset and development of prurigo pigmentosa. A study[12] conducted by Kobayashi et al. (1996) showed that it can arise from contact allergic reactions to p-amino compounds that are used in the manufacturing of clothing.

Similarly, in a study[13] analyzing 50 cases of PP showed five patients developing PP after mechanical irritation from things like bandages, body-scrubbing or friction from clothing.

Extremely high blood sugar

While a less common cause of the keto rash, cases have been reported of patients development PP who have diabetes. This is likely due to uncontrolled blood glucose levels. As patients symptoms decreased when blood glucose levels were decreased and stabilized, this indicates that blood sugar control may have an active role in the development and progression of this condition.

How to treat the keto rash?

There are a few treatment options that can help control the development of prurigo pigmentosa. Complete resolution of the condition might take from one to several weeks[14]. However, lesions typically heal leaving behind a net-like pattern on the skin of hyperpigmentation[15] (darkened spots of skin) that may stay even after the rash has disappeared.

While treatment options may not work for everyone, some successful options include:

Let it run its course

In many cases of diagnosed PP, the lesions receded on their own. If it has developed as a side-effect of entering ketosis, allowing the body to adjust to using ketones as fuel may allow the rash to heal by itself.

Increase carbohydrate intake

Some research suggests that excessive fasting or being in a state of ketosis can initiate the onset of the keto rash. Based on current research, there is no successful cure for the keto rash that allows an individual to stay in ketosis. Increasing carbohydrate intake in order to decrease ketone blood levels has been proven effective at curing prurigo pigmentosa.

The most effective way to address this issue is to do a test. Increase your carb intake for a few days enough to take your body out of ketosis. By doing so, you reduce blood ketones and can see if the rash starts to heal. If it does begin to recede, lower carb intake again to get back into ketosis and note any changes to the rash. If the rash worsens, this is a sign your body may be reacting to ketones unusually.

A 2013 study on PP[16] and a strict ketogenic diet found that incorporating carbohydrates back into the diet helped to improve the severity of the rash. Similarly, if remaining on the ketogenic diet, careful prescription of carbohydrates[17] may enable to rash to heal without sacrificing ketogenesis.

Try eliminating allergenic foods

Inflammatory reactions can be caused by many foods, even keto-compliant ones. In order to determine if what you’re eating may be contributing to a rash flare up, trying an elimination diet may be worthwhile. Introducing new foods or eating large amounts of specific foods can cause the body to react in a way that it normally would not.

Here are some common allergenic foods you may want to try eliminating:

Eggs

Dairy

Tree nuts

Seafood

Try this protocol to do an elimination diet:

Remove the specified foods from your diet for 30 days. Check if your rash has receded or disappeared after the period has finished. If it has, introduces one food again into your diet and wait 1-2 weeks. If the rash hasn’t come back, add one more new food and follow the same procedure. Continue adding in one new food every 1-2 weeks as long as no symptoms appear. If the rash appears at any point after introducing a food, that food is the likely trigger for the rash.

Fix nutrient deficiencies

While nutrients deficiencies are linked to a variety of conditions, vitamin A, vitamin B 12, and vitamin C, specifically, have been linked to a variety of acute and chronic skin conditions[18]. Vitamin D[19] and omega-3 fatty acids[20] also play a crucial role in the regulation of the inflammatory response. Since the keto rash is an inflammatory skin condition, there is some evidence to support optimizing levels of vitamin D and fatty acids may help to control or reduce inflammation levels.