In early December, about a week and a half into my nutritional ketosis experiment I started to develop a rash on my body. It began in my abdomen, near my collar bones, and my lower back. It was only slightly itchy (I’ve attached a few pictures that I took from that time showing what it looked like as it was beginning).
Over time it gradually spread to cover much of my trunk (unfortunately I didn’t take pictures of this), but it looked like this.
I thought it might’ve been related to a viral infection or something (even though I never felt sick), because I know that
sometimes certain virus’ can give you rashes (the general term for this is a ‘viral examthem‘).
When it didn’t go away after two weeks, I figured I should get myself checked out by a dermatologist. He diagnosed me with a skin condition called ‘pityriasis rosea.’ This is a condition that presents with a rash that only covers the trunk (exactly like mine), but the cause is unknown. No treatment is really needed, and it is supposed to go away by itself in 5-8 weeks.
One of the questions the dermatologist asked me was whether there was any thing new in my life. I mentioned that I’d been trying a ketogenic diet and have been in ketosis for the past few weeks. When I asked if there could be a connection, he emphatically said, “No. There is no relationship between your diet and this rash.”
Since he was so confident, I took what he said at face value and continued to chug along hoping for the rash to disappear. By the time week 5 rolled around the rash had waxed and waned a bit, but never really went away. About 8 weeks later it almost completely went away. I was pretty relieved at this point.
The week when the rash started getting better and almost went away was when I was staying in NYC and started cheating there, eating a bunch of carbs (hard to resist NY cheesecake), causing me to fall out of ketosis. Then when I came back home and dug back into my n=1 nutritional ketosis experiment getting my blood ketones back up, that’s when the rash reappeared!
So I did what any rational person would. I turned to google and found few interesting links. This was the message thread that gave me my ‘Aha!” moment. The picture that was posted was almost identical to mine!
Turns out there is a skin condition that presents with the same rash that I had AND it can be brought on by ketosis! It’s called pruritis pigmentosa.
I had to prove this to myself, so I did what any diligent n=1 experimenter would do: I ate more carbs. The following morning, that rash got better. I ate more carbs. The rash got even better. This pattern continued for a few days until the rash had almost completely disappeared… and my ketones went waaaaaaay down.
Since there isn’t really much written about this condition, I did a quick literature search on pubmed and will write brief summaries on the relevant papers:
Here is some general background:
Prurigo Pigmentosa (PP)
- 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:
- 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.
It’s interesting that despite the association found with ketosis, no clear explanation exists as to why. Why do ketones cause this rash? Is it because of the ketones themselves? Or because of some other factor that occur with the changes in metabolism seen with ketosis?
It seems like the answer to these questions is fairly far off. In the mean time, at least there are some effective treatments.
My Recommendation Based On My Own Experience and Research
I felt it was important to gather all this information in one place in case anyone else out there doing a very low carb or ketogenic diet has the same rash. I don’t want anyone else to be misdiagnosed, especially since there isn’t any lay literature out there, and many doctors don’t really know about this (as in my case).
If you’re in ketosis, the best way to treat this rash is simply to eat more carbs! It’s simple and cheap and it worked with me and many of the other individuals in the scientific literature, and hopefully it will work for you. If that doesn’t work, you can consider having your doctor try some of the medications listed above. Feel free to send them to this post since I tried to provide easy links to the source papers.
Just launched TheKetoRash.com which is where I will continue to post the most up to date research on this topic. I want to make it the most comprehensive resource available on the keto rash. I’ve also setup forums and a facebook group for people to discuss their own experiences. Head on over to check it out.