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Updated on November 15, 2023
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What is Keto Breath? Why It Happens and How to Fix It

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Keto breath is a distinct taste or odor in the mouth that comes from eating a ketogenic or low-carb diet. It differs from person to person, commonly described as:

  • Metallic
  • Overly sweet, like rotten fruit
  • Chemical, like nail polish remover

The taste or smell is a side effect that often occurs when you first start eating keto or low-carb. Not everyone who eats a low-carb diet will develop keto breath. For those who do, it’s typically temporary.

salad and avocado with flowers placed on wooden table

What is the Keto Diet?

The ketogenic diet, also known as keto, is a popular low-carbohydrate, high-fat, and high-protein diet. Many people use it to lose or manage weight.3 

People on a keto diet commonly eat foods like:

  • Meat and eggs
  • Seafood
  • Non-starchy vegetables and low-sugar fruits
  • Full-fat dairy
  • Nuts and seeds

Keto focuses on replacing carbs with fats in an effort to trigger a metabolic state called ketosis. During ketosis, your body produces ketones in the liver to help you burn fat as energy.

Some people adapt relatively quickly to a state of ketosis, but others do not. You must be careful when changing your body’s metabolic state. If you’re curious about trying keto, speak with your doctor to assess whether it’s the right choice.

What Causes Keto Breath?

When your body goes into ketosis, it has two ways of excreting the high levels of ketones it produces:

  • Exhalation
  • Urination

Because of this, you may notice a change in your breath and urine. These changes signal that you’ve entered ketosis.

Keto breath usually becomes noticeable within a couple of days or weeks of starting a keto or low-carb diet. It will likely subside after a few weeks once your body gets used to the new diet.

Can You Prevent Keto Breath?

There’s no real way to prevent keto breath if you intend to eat a keto diet.

If you’re concerned about developing breath, you can use a ketone breath analyzer to determine how many carbs you can eat without leaving ketosis. That way, you can increase your carbs to offset bad breath while still getting the effects of ketosis.

How to Fix Keto Breath: Home Remedies

Keto breath happens as a byproduct of metabolic processes. The only way to completely eliminate it is to switch your eating style or wait for it to subside.

However, there are a few ways you can keep your breath smelling and tasting better until then:

1. Drink More Water

Drinking water can help flush out the ketones more quickly through urination. It can help prevent or improve bad breath. 

Staying hydrated will also help alleviate dry mouth, which can be a side effect of keto.

2. Tweak Your Macros

Adjusting carbs, protein, and fat intake can help reduce keto breath. Eating high amounts of protein can worsen your breathing by producing odorous ammonia. 

You can also increase your carb intake to improve your breath. Only bump up your carbs slightly if you want to stay in ketosis.

3. Use Breath Fresheners

You can mask the unpleasant odor and taste with chewing gum, mints, and mouth spray. These won’t fix the problem, but they can improve things until keto breath goes away on its own.

Always check the sugar and carbohydrate content of whatever fresheners you use to ensure they’re keto-friendly.

4. Practice Good Oral Hygiene

Paying special attention to your oral hygiene routine can be beneficial for keto breath. Brush at least twice a day, floss once daily, and use an alcohol-free mouthwash regularly to keep your mouth clean of bacteria.

5. Give It Time

Keto breath isn’t permanent. Once your body gets used to ketosis, the odor and taste should disappear. 

Be patient, and your breath will return to normal within a few weeks.

Other Oral Health Side Effects from the Keto Diet

Certain symptoms can suggest that you've entered ketosis, including dry mouth and increased thirst.7 Other symptoms of ketosis include frequent urination and decreased hunger or appetite.

Make sure you stay well-hydrated. This helps prevent you from developing a dry mouth on top of keto breath.


Keto breath occurs when your body excretes ketones through exhalation. Ketones are a byproduct of entering ketosis, a metabolic state brought on by the low-carb diet known as keto.

Keto breath may smell or taste metallic, fruity, or like nail polish remover. It typically develops within a few days or weeks after you start eating keto and will subside after weeks on the diet.

You can’t prevent keto breath, but you can alleviate it while waiting for it to go away. You can try adjusting your macros, drinking more water, and using breath fresheners to improve keto breath.

Last updated on November 15, 2023
7 Sources Cited
Last updated on November 15, 2023
All NewMouth content is medically reviewed and fact-checked by a licensed dentist or orthodontist to ensure the information is factual, current, and relevant.

We have strict sourcing guidelines and only cite from current scientific research, such as scholarly articles, dentistry textbooks, government agencies, and medical journals. This also includes information provided by the American Dental Association (ADA), the American Association of Orthodontics (AAO), and the American Academy of Pediatrics (AAP).
  1. Woelber, J., et al. “An oral health optimized diet can reduce gingival and periodontal inflammation in humans - a randomized controlled pilot study.” BMC Oral Health, National Library of Medicine, 2016.
  2. Batch, J., et al. “Advantages and Disadvantages of the Ketogenic Diet: A Review Article.” Cureus, National Library of Medicine, 2020.
  3. Masood, W., et al.Ketogenic Diet.” StatPearls, National Library of Medicine, 2021.
  4. Crosby, L., et al. “Ketogenic Diets and Chronic Disease: Weighing the Benefits Against the Risks. Frontiers in Nutrition, National Library of Medicine, 2021.
  5. Oh, R., et al.Low Carbohydrate Diet.” StatPearls, National Library of Medicine, 2021.
  6. Scardina, G., et al. “Good oral health and diet.” Journal of Biomedicine & Biotechnology, National Library of Medicine, 2012.
  7. Bostock, E., et al. “Consumer Reports of ‘Keto Flu’ Associated With the Ketogenic Diet.” Frontiers in Nutrition, National Library of Medicine, 2020.
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