Diet, Causes, Symptoms, Treatments, and More

Keto rash, or prurigo pigmentosa, is a type of rash that can develop when the body enters ketosis. It is a rare inflammatory condition that can occur if you follow a ketogenic diet. It is also called Nagashima disease.

Anybody can develop keto rash. However, females are twice as likely as males to develop the rash. It is also more common among people of Asian descent.

This guide explains what causes keto rash and how to recognize symptoms. It also discusses treatment options, when to contact a doctor, and more.

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Following a ketogenic, or keto, diet involving consuming foods that are low in carbohydrates and high in saturated fats. As the body is unable to use sugar from carbohydrates, it instead uses ketone bodies. Learn more about ketones.

The liver creates ketone bodies from stored fat. Once you begin using ketone bodies for energy, this is known as ketosis. Although it is rare, some people in ketosis can develop keto rash. It can take days or months for the rash to appear.

Learn more about keto diets.

Aside from a keto diet, other possible causes of ketosis and keto rash include:

  • fasting
  • undergoing bariatric surgery
  • having insulin-dependent diabetes

Ketosis is different from ketoacidosis. Learn more about diabetic ketoacidosis.

Other possible causes of the prurigo pigmentosa rash include:

What are the symptoms of keto rash?

Symptoms of keto rash include:

  • raised red or discolored spots that combine to form a pattern
  • a symmetrical rash on the trunk, usually affecting the:
    • upper back
    • abdomen
    • chest
    • sacrum, which is just above the tailbone
  • itchiness
  • inflammation
  • hyperpigmentation once the inflammation goes away

It is rare for keto rash to affect the face or limbs.

You can also experience symptoms of so-called keto flu when following a keto diet. Learn more about keto flu.

Learn more about other possible causes of an itchy rash.

What are the stages of keto rash?

The early stage of keto rash is usually characterized by itchy, inflamed bumps or swelling with fluid inside. These tend to become scale or crust over.

As the condition progresses, these lesions will connect and form a symmetrical pattern.

Hyperpigmentation occurs once the inflammation resolves.

These are the typical stages of keto rash. However, if your rash does not follow these stages, it does not necessarily mean that you do not have keto rash. Contact your doctor as soon as you notice a rash for advice.

Is there a cure for keto rash?

It may be beneficial to cure keto rash by bringing carbohydrates back into your diet. However, you may also require other treatments, such as antibiotics.

How do I treat keto rash?

Treatments for keto rash can depend on the stage of the condition as well as the cause.

You may be able to treat keto rash that occurs as a result of following a keto diet by adding carbohydrates back into your diet. This may be enough to resolve the rash, though you may also require additional medical treatments.

Other treatments for keto rash focus on antibiotics, including tetracycline antibiotics such as minocycline and doxycycline.

Unlike some other rashes, keto rash does not respond to topical or systemic corticosteroid treatment.

It is currently not possible to treat hyperpigmentation. However, this will fade over time.

Contact your doctor as soon as you notice a rash. It is important to determine the cause of the rash so that you can receive the right kind of treatment.

You should also contact your doctor before making any significant changes to your diet.

How do doctors diagnose keto rash?

Your doctor will take a full medical history and perform a physical examination. If they suspect that you have keto rash, they may also ask you questions about your diet. It is important to let your doctor know about your dietary habits, particularly concerning your intake of carbohydrates.

Your doctor will also order tests to rule out other possible causes, such as allergic contact dermatitis or a reaction to a medication.

Tests can include patch tests and skin biopsies.

During a patch test, a medical professional will place known allergens on your skin, usually on your back, and put patches over them. They will then check the patches again within 48–96 hours to see if you have experienced a reaction. Learn more about allergy skin testing.

Skin biopsies involve removing a small section of the affected skin for laboratory analysis. This can help with identifying any infections or conditions, such as psoriasis. Learn more about skin biopsies.

Keto rash is a rare inflammatory dermatosis. A 2019 article highlights that there have been only around 300 cases, most of which were reported in Japan. As of 2019, there have been fewer than 20 reported cases of keto rash in the United States.

However, it is possible that doctors are underdiagnosing keto rash. Symptoms can be similar to those of other conditions, and medical professionals can misdiagnose it as a more common skin condition, such as eczema or contact dermatitis.

What are the risk factors for keto rash?

There are certain risk factors and triggers for keto rash. These include:

Conditions that make you more likely to develop keto rash include:

  • diabetes
  • anorexia nervosa
  • Sjögren’s disease

Contact your doctor if you have any concerns about keto rash.

What are the complications of keto rash?

Keto rash can feel itchy, which may result in scratching. It is important to try to avoid scratching a rash, however, as this can result in complications such as infections.

Symptoms of an infection include:

  • pain
  • warmth in the area of ​​the rash
  • swelling
  • crusting
  • a streak that may appear red in light skin tones and otherwise discolored in dark skin tones
  • yellow or green fluid

Contact your doctor if you experience an infection.

You can help prevent keto rash by making sure that you get enough carbohydrates in your diet. The body uses sugar, or glucose, from carbohydrates for energy. If you do not get enough carbohydrates, the liver will create ketone bodies for energy instead. This can result in ketosis.

You may not be able to prevent keto rash if it occurs due to an underlying health condition. Contact your doctor if you have concerns about keto rash.

Keto rash is a rare inflammatory dermatosis that can occur when the body enters the metabolic state of ketosis. This can happen as a result of following a keto diet. Other causes of keto rash include certain health conditions and contact with some substances.

If keto rash occurs due to following a keto diet, introducing carbohydrates back into your diet may resolve the rash. You may also require medical treatments such as antibiotics.

Contact your doctor as soon as you experience a rash. They will be able to carry out tests to confirm the diagnosis and advise on the right treatment for you.


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