This is not a common problem on low carb, but for the few people experiencing it, it can be really annoying: Itching.
This itching – sometimes called the “keto rash“1 – can be troublesome, sometimes even interrupting sleep. The itching and rash are almost always symmetrical on both sides of the body. It most often develops over the chest, back, armpits and sometimes in the neck (see image above).
What is the reason for this problem, and how can it be cured?
There are many posts about this online, and many different theories. The time has come to make it simple, Diet Doctor style. Here’s everything you need to know.
The cause of the keto rash
While there are dozens of theories about this problem, each more weird and unlikely than the next, I believe there’s a very simple answer. This is based on many people’s experiences,2 and the limited scientific studies available.3
Here are the clues, and the conclusion:
- The itching usually starts soon after people get into ketosis. It stops within a day or so if people eat more carbs and exit ketosis.
- It can often get worse in hot weather, or after exercising.
- The usual distribution of the itch and rash matches areas where sweat can accumulate.
- When in ketosis sweat can contain the ketone body acetone.
- Acetone can be irritating at high concentrations.
I think there is good reason to believe that the itching that some people experience in ketosis is caused by ketones in sweat, perhaps as this dries on the body.
How to cure the keto rash
There are several things you can do to cure keto rash:
- Clothing: Wear comfortable clothing for the climate, so that you don’t sweat more than necessary. Use air conditioning when appropriate.
- Shower: After exercising it might help to take a shower – after you’re finished sweating.
- Change exercise plans: If the itching is really troubling you might want to skip exercise for a few days, or do something like brief weight training that does not produce perspiration.
- Exit ketosis: If the the steps above are not effective enough, exiting ketosis will reliably cure the issue within a day or two. This can be done by eating about 50 grams of carbs or more every day. To still get most of the benefits of a keto diet – at least for weight loss and type 2 diabetes reversal – you can do a more liberal low-carb diet (50-100 grams of carbs per day) and add intermittent fasting.
- Other treatments: There are many other treatments suggested online; like antibiotics taken for weeks or months and/or special creams. These will likely offer temporary relief at best.4 I definitely advise not to use oral antibiotics, as the side effects and risks are much worse than the doubtful and temporary benefits. Steroids, anti-fungal creams and anti-histamines appear not to be effective at all. There’s a safe, simple and free solution if you need it – number four, above. Use that instead.
If you get rid of the keto rash by exiting ketosis, can you ever use ketosis again? The answer is likely yes.
If you felt great in ketosis and had a lot of benefits, you may want to try again. The keto rash may stay away. Some people appear to get it only once, or only early in ketosis, when first starting out on a low-carb diet (given time, the body may excrete fewer ketones in the sweat). Remember, most people in ketosis don’t get the rash at all.
Keep the advice above in mind. And if all else fails, just eat a bit more carbs and the problem will go away.
Have you experienced keto rash? Do you want to share what helped and what did not? Feel free to leave a comment below!
Potential other side effects on low carb
Another name that is sometimes used for this condition is “Prurigo pigmentosa“.
The name means that it itches (“prurigo”), and that long-term, after many weeks, it can result in increased pigmentation (“pigmentosa”) in the affected skin area, looking like darker patches.
This increased pigmentation, should it occur, fades very slowly after the rash is cured. ↩
Here are a few places to read about people’s experiences with keto rash:
- The Keto Rash Blog
- The Keto Rash on Facebook
- The BJJ Caveman: Prurigo Pigmentosa – The Ketosis Rash Nobody Warned Me About
- Bulletproof Forums: Keto Rash?
- Diabetes Daily Forums: Keto Rash
- Reddit: Who needs keto sticks when you’ve got the rash! :|
Here are a few relevant studies:
- J Dermatol. 2012: Prurigo pigmentosa: clinicopathological study and analysis of 50 cases in Korea.
- J Eur Acad Dermatol Venereol. 2012: Prurigo pigmentosa: a clinicopathologic study of 16 cases.
- Am J Dermatopathol. 2003: Prurigo pigmentosa: a distinctive inflammatory disease of the skin.
This study references the experience of treating the keto rash (prurigo pigmentosa) with antibiotics. It did have an effect – possibly due to anti-inflammatory properties – but once the treatment was stopped the rash reappeared.