Keto Diet Skin Rash: Why Keto Rash Happens and How to Fix It
Skin CareDiet & Skin Health
Explore This Topic

Keto Diet Skin Rash: Symptoms, Causes, and Fixes

Keto Diet Skin Rash: Symptoms, Causes, and Fixes
iStock
By
Published on October 16, 2024
by

When you begin the ketogenic diet — a very low carb, high-fat diet — you may go into it with certain expectations about weight loss, blood sugar management, and more. You might even be prepared for certain unwelcome side effects of the so-called keto flu, like fatigue, brain fog, or irritability. But some results of the keto diet may be surprising.

Keto rash is one such side effect. For certain people, the keto diet has a strong impact on skin health. Luckily, keto rash is uncommon, but it’s important to know what it is in the event you develop the issue.

Learn more about the keto rash, why ketosis can cause a red, itchy rash, how to treat it, and if there’s anything you can do to prevent it.

What Is a Keto Diet Skin Rash?

Keto rash is a body rash that’s associated with ketosis, a metabolic state that happens when the body switches from utilizing carbohydrates as your main fuel source to fat.

The medical term for this rash is prurigo pigmentosa, says Eamonn Maher, MD, a dermatologist and an assistant professor at the University of Minnesota in Minneapolis who specializes in complex medical dermatology.

Currently, this rash is most often associated with the body being in a state of ketosis. That can happen because someone is voluntarily following a keto diet or is fasting, has diabetes, has undergone bariatric surgery, and more, per research.

 According to one literature review, about one-quarter of these cases are associated with dietary changes, says Christopher Chu, MD, a board-certified dermatologist and dermatopathologist at Pure Dermatology in Austin, Texas. “A subset of these — about 40 percent — happened following the adoption of a ketogenic diet,” he says.

That said, the keto rash is not necessarily something to expect if you’re going on the keto diet. It’s generally pretty rare, says Dr. Maher. Keep reading to learn the symptoms to watch for.

Keto Rash Symptoms

This can change in appearance, says Hannah Kopelman, DO, a New York City–based dermatologist and the host of the Derm Club podcast:

  • Initially, the rash may consist of red bumps that appear on the neck and trunk. It is extremely itchy, causing you to scratch your skin frequently.
  • The rash then leaves behind a postinflammatory hyperpigmentation that has a brownish or darker color on the skin. Often this is in a reticulated (“lacey”) pattern.
This rash does not start on day 1 of the keto diet, adds Dr. Kopelman. “Your body has to get into the metabolic state of ketosis first. We may see the rash develop in two to four weeks after the diet,” she says. In fact, one literature review on 19 cases from 2015 to 2021 found that on average, the rash appeared 31 days after a person started the diet, but it could be as long as four months.

 That’s why it can be challenging to connect the dots between the keto diet and a rash, especially if you’ve been on the diet without problem for a while.

Why the Keto Diet Causes a Skin Rash

At the moment, experts don’t fully understand why ketosis causes a body rash to develop in some people. “It tends to be present in more moist areas of the body, like the back, chest, abdominals, and underneath the breasts. It’s conjecture, but we think that there may be something going on where ketones that get produced are getting exuded in sweat,” says Maher. “Just like we use ketones as fuel, it’s possible that some bacterial species are making use of these ketones, leading to an overgrowth in bacteria,” he says. This theory is supported by the treatment for prurigo pigmentosa: antibiotics. More on that next.

Treating Keto Rash

First, if you have a rash with the description above, see a dermatologist for an evaluation and possible diagnosis. “Prurigo pigmentosa is frequently misdiagnosed. It’s often mistaken for other conditions, like eczema, contact dermatitis, or others,” says Dr. Chu. The downside of this is that keto rash won’t respond to topical steroids, which may be recommended for other skin conditions, he says. It’s important to tell your provider about new lifestyle changes, including to your diet.

The treatment for keto rash (prurigo pigmentosa) is antibiotic therapy, says Maher. Doxycycline is the antibiotic most often used. It is a tetracycline antibiotic that reduces bacteria, and it’s often used to treat acne.

 In addition to its bacteria-killing properties, the antibiotic also helps decrease inflammation, Maher points out. It’s not clear, however, if it’s the antibacterial or anti-inflammatory properties that makes this medication effective, he says.

Typically, antibiotics are given orally. But you may be able to use topical antibiotics if there is a reason you can’t or would like to avoid taking oral antibiotics, says Maher. Always discuss the best option for you with your provider.

Another treatment for the keto rash is to quit the keto diet, says Kopelman. It’s something that’s been shown to clear the rash in case studies.

 “We’ve seen that the rash subsides and resolves after stopping the diet. The rash might leave residual hyperpigmentation for a few weeks, but that will gradually fade,” she says.

Whether you can stop the keto diet depends on why you’re following it in the first place. For example, if you’re on the keto diet voluntarily, the keto diet might not be right for you.

But if you’re following the keto diet to treat a specific medical condition and your healthcare provider recommends remaining on it, you don’t necessarily have to stop just because you get this rash, adds Maher. “The rash is not a harmful condition,” he says.

Preventing Keto Rash

The main way to prevent keto rash — prurigo pigmentosa — is to avoid going on the keto diet altogether. If you start the keto diet and develop a rash, you can prevent it from recurring by stopping the diet and getting out of ketosis. “Unfortunately, if you are someone who develops prurigo pigmentosa when entering ketosis, there’s no intervention that can prevent the disease. The best option is to introduce a small amount of carbohydrates,” says Chu.

The Takeaway

Keto rash (prurigo pigmentosa) is a rare skin rash that is triggered when the body enters a state of ketosis, and treatments include antibiotic therapy and stopping the keto diet. If you have a rash that you’re being seen for by a care provider, keep them updated on changes to your habits, including your diet, which will help with proper diagnosis. If you develop a rash in response to the keto diet, work with a registered dietitian to help you identify another eating approach that aligns with your goals — and works for your body.

Meet Our Experts
See Our Editorial PolicyMeet Our Health Expert Network
Amy-Spizuoco-bio

Amy Spizuoco, DO

Medical Reviewer
Castle Connolly Top Doctor

Amy Spizuoco, DO, is a board-certified dermatologist and dermatopathologist. Dr. Spizuoco has been practicing medical, surgical, and cosmetic dermatology, as well as dermatopathology in New York City for 12 years.

She did her undergraduate training at Binghamton University, majoring in Italian and biology. She went to medical school at the New York Institute of Technology College of Osteopathic Medicine. After medical school, she completed her dermatology residency at Lake Erie College of Osteopathic Medicine–Alta Dermatology in Arizona. During that time she studied skin cancer surgery and pediatric dermatology at Phoenix Children’s Hospital and attended dermatology grand rounds at the Mayo Clinic in Scottsdale. After her residency, Spizuoco completed a dermatopathology fellowship at the Ackerman Academy of Dermatopathology.

She was previously an associate clinical instructor in the department of dermatology at the Icahn School of Medicine at Mount Sinai in New York City. She is on the editorial boards of Practical Dermatology and Dermatology Times.

See full bio

Jessica Migala

Author

Jessica Migala is a freelance writer with over 15 years of experience, specializing in health, nutrition, fitness, and beauty. She has written extensively about vision care, diabetes, dermatology, gastrointestinal health, cardiovascular health, cancer, pregnancy, and gynecology. She was previously an assistant editor at Prevention where she wrote monthly science-based beauty news items and feature stories.

She has contributed to more than 40 print and digital publications, including Cosmopolitan, O:The Oprah Magazine, Real Simple, Woman’s Day, Women’s Health, Fitness, Family Circle, Health, Prevention, Self, VICE, and more. Migala lives in the Chicago suburbs with her husband, two young boys, rescue beagle, and 15 fish. When not reporting, she likes running, bike rides, and a glass of wine (in moderation, of course).

See full bio
See Our Editorial PolicyMeet Our Health Expert Network
EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
  1. Masood W et al. Ketogenic Diet. StatPearls. June 2023.
  2. Daneshpazhooh M et al. Remission of Prurigo Pigmentosa After Breaking Ketogenic Diet and Resuming Regular Diet. Advanced Biomedical Research. August 30, 2022.
  3. Mufti A et al. Clinical manifestations and treatment outcomes in prurigo pigmentosa (Nagashima disease): A systematic review of the literature. JAAD International. April 2021.
  4. Xiao A et al. Ketogenic Diet-Induced Prurigo Pigmentosa (the “Keto Rash”): A Case Report and Literature Review. Journal of Clinical and Aesthetic Dermatology. December 2021.
  5. Doxycycline. National Library of Medicine. September 2024.