Quick Public Service Announcement: “Ketosis Induced Rash”

I’ve heard smatterings of anecdotes over the years about folks coming down with rashes while generally LC dieting (Paleo / Primal / Plain Jane LC). Tough to pin it on anything certain until someone experiments extensively and then does the PubMed crawl. So, posting this simply to get word out, in case anyone has had this condition and was unaware that it’s pretty well associated with ketosis, chronic fasting, etc.

Via BJJ Caveman. See his post for a substantial comment thread as well as the links to all the studies he cites, below. From a quick scan of his 170 comments, there’s a surprising number of people afflicted. Guess what the common association is.

Prurigo Pigmentosa – The Ketosis Rash Nobody Warned Me About

Purigo Pigmentosa
Purigo Pigmentosa
  • The rash is usually symmetric and predominantly located on the trunk involving the back, chest, and neck.
  • The cause of this is still unknown however there are many suspected causes:
    • Ketosis
    • Fasting / anorexia nervosa
    • Diabetes
    • Pregnancy
    • H. pylori infection
    • Sweating
    • Friction from clothing
    • Allergic exposure
    • Autoimmune disease
    • Sometimes no causes are found
  • Most of the research has been focused on exploring the relationship between diet / ketosis and the rash
  • It usually starts off as a red raised rash and over time as it goes away it turns darker in color.
  • The rash can last from anywhere from months to years.
  • The best treatment for the rash thus far appears to be with antibiotics such as minocycline, dapsone, or doxycycline. Treatment usually lasts around 2.5 weeks.
  • This most recent study from 2012 found that 7 of 22 patients with PP tested for urinary ketones had elevated ketone levels.
    • “The mechanism by which dietary modifications provoke PP is not yet clear, but there are several previous reports of an association between ketosis and inflammation.”
  • Another study from 2012 found that 6 of 21 patients with PP had showed recent weight loss due to strict dieting.
  • This study from 2012, perhaps one of the most interesting found that 6 out of 10 patients with PP who had their urine tested had elevated ketones in their urine, and 2 out of 4 patients who had their blood ketones tested had elevated blood ketones (3.2 mmol/L and 1.65 mmol/L, well within the range for nutritional ketosis). Most of these patients were ketotic due to dieting and/or fasting.
    • “Our findings also support the argument that ketosis produced by fasting or dieting may play a role in the pathogenesis of prurigo pigmentosa. Therefore, physicians need to warn that excessive fasting can cause prurigo pigmentosa.”
  • This study found that menstruation made symptoms worse for 1 of 11 patients.
  • Here is a case report of a ‘fatty young man’ who developed soft-drink ketosis (a type of noninsulin dependent diabetes and ketosis induced by too many soft drinks) and then had PP. The PP went away after he cut out the soft drinks. I like the fact that they described him as a ‘fatty young man.’
  • Another case report of someone with type 1 diabetes and ketosis who developed PP. 5 days after the ketosis was treated with insulin the rash went away (this seems to be the pattern typically found in the early literature)
  • This study from 1996 found that 8 of 10 patients with PP were in ketosis (due to dieting, loss of appetite, or diabetes). The rash cleared when ketosis diminished. In one patient the rash came back when he fell back into ketosis.

He’s also set up a specific website: TheKetoRash.

This has been a Public Service Announcement from Free the Animal.

Richard Nikoley

I'm Richard Nikoley. Free The Animal began in 2003 and as of 2021, contains 5,000 posts. I blog what I wish...from health, diet, and food to travel and lifestyle; to politics, social antagonism, expat-living location and time independent—while you sleep—income. I celebrate the audacity and hubris to live by your own exclusive authority and take your own chances. Read More


  1. j3nn on September 20, 2014 at 11:19

    Starvation is not the preferred state of the body.

  2. Ilaine on September 20, 2014 at 11:46

    Just wanted to mention that there are a lot of rashes which look similar but are not prurigo pigmentosa, so if you get a similar looking rash, don’t assume it is PP, which is rare. I have had tinea versicolor for decades, not uncommon in warm, humid environments like Louisiana, where I am from, and much easier to treat. For tinea versicolor, apply Selsun or generic selenium sulfide shampoo, let dry, rinse. Repeat as needed, daily or weekly until cleared. Prescription level selenium sulfide lotion works better but Selsun or generic selenium sulfide shampoos are available over the counter. A dermatologist may be warranted. BTW the prescription level lotion smells good, the shampoo stinks.

  3. Rita Weasel on September 22, 2014 at 09:07

    I don’t know, Ilaine – in looking over the KetoRash blog, the commenters all seem to have a change in diet as the common denominator before the presentation of the rash. I, for one, experienced a horrible rash while low-carbing and adding in RS and Prescript-Assist. The doctors/pharmas/etc. could not conclusively say what was wrong with me; they just shot steroids in my ass and said “good luck, kid.” I ate “normally” until the wicked beast left my skin, then slowly added the RS and PA back into my regime. The moral of the story – in my case, anyway – was that the microbiome needed to be treated with more respect and sensitivity than I was allowing. You can’t throw just anything down your mouth hole without some sort of reaction.

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