Keto Breath: 3 Reasons You Have It and 6 Ways to Cure It

Blog Categories


Keto Breath: 3 Reasons You Have It and 6 Ways to Fix it



One of the worst side effects of going low-carb is keto breath.

Even if you’re crazy about your dental hygiene, start a ketogenic diet and you may find yourself struggling (and losing) the fight against bad breath.

The good news is that it doesn’t have to be this way. You can solve this embarrassing problem and love everything about being on a keto diet.

What Is Keto Breath?

Is keto breath the same as high school math teacher bad breath?

Bad breath, also known as halitosis, is typically characterized by unpleasant smells coming from your mouth region. It’s a common symptom of ketosis, and usually, the causes of bad breath include[*]:

  • Poor dental hygiene
  • Dental problems like gingivitis
  • Certain foods (like onions, coffee, and garlic)
  • Tobacco products
  • Specific health conditions
  • Dry mouth
  • Oral infections
  • Medications
  • An overgrowth of bad gut bacteria

Though it’s not fun, you’ll want to visit your dentist and doctor to rule out a few of these issues if you’re experiencing less than fresh breath.

Unlike the general war of smells from leftover food particles and bacteria in your mouth that is halitosis, keto breath is very specific.

It’s been described as a pungent, acidic, and fruity smell. Although some say it’s more of a metallic taste in your mouth. Others claim keto breath (and urine) smell more like nail polish remover or even varnish.

The silver lining to keto breath is that it means you’re actually in ketosis.

Why Being in Ketosis Can Cause Bad Breath

There are three main reasons why your breath might be a little funky on a ketogenic diet:

  • Acetone is produced as a ketone and extra ketones need to leave your body.
  • Ammonia generated via protein digestion also needs to bounce.
  • Dehydration causing dry mouth compounds halitosis and keto breath.

Check out how each of these is to blame for ketosis breath.

Browse our curated collection of fan-favorites and discover your new favorite snack or supplement.

Shop Best Sellers

#1. Acetone Produced Via Ketosis Causes Keto Breath

To understand this explanation for keto breath, you have to fully understand how keto works in the first place.

When you switch from the Standard American Diet (SAD) of eating close to 300 grams of daily carbs to a ketogenic diet of less than 25 grams of daily net carbs, your body will stop using glucose for energy and start to use fat.

Being in ketosis is when your body kicks into fat-burning mode, using fat for fuel instead of sugar.

In order for your body to use this type of fuel, your liver produces ketones, which is where the word “ketosis” comes from.

Your body produces three main types of ketone bodies:

Your body makes a small supply of ketones even if you’re not in keto. But once you switch, your liver goes into overdrive ketone production.

The result?

Sometimes your body has too many ketones.

Ketones are harmless. When you have an excess, your body just lets them pass through via your urine or your breath.

As ketones circulate in your blood, they interact with the air in your lungs before being released from your mouth.

Since acetone is an ingredient in nail polish remover, that could explain the strange, sweet smell of your breath and pee.

Studies show besides testing for acetoacetate in urine, acetone on your breath is a proven sign of being in ketosis[*].

While switching to keto will cause this acetone release, not getting your macros right may trigger the next possible reason for your keto breath too.

If you’re worried about your bad breath, you can check your ketone levels and verify whether they are to blame. 

#2. Eating Too Much Protein Can Also Cause Keto Breath

A standard ketogenic diet (SKD) relies on a breakdown of daily calories from macronutrients as follows:

  • 70-80% of your calories come from fat
  • 20-25% from protein
  • 5-10% from carbs

In an effort to cut carbs, many new keto dieters eat too much protein instead of eating more fat.

Or they don’t calculate their macros correctly and eat much more protein than they should — especially women who need a lot less protein than men[*].

When you consume more protein than your body can use, you’ll come face-to-face with keto breath.

Your body naturally produces ammonia when it breaks down proteins[*]. But just like acetone, that extra ammonia gets released through your urine and your breath.

If you’ve ever smelled ammonia before, you know it’s super strong and chemical-like, similar to many cleaning products. Ammonia is so powerful it’s not even recommended to inhale. 

It’s no wonder you have very strong breath and urine when your protein levels are too high.

You’ll want to stick to the low end of the protein scale if you’re not building muscle or exerting yourself with high physical activity every day.

#3. Dehydration Can Cause Dry Mouth and Compound Keto Breath

A low-carb diet can cause dehydration, which is when you take in less water and fluids than your body uses or expels.

When you’re eating carbs, your body holds the excess glucose you don’t use as glycogen stores in your liver and muscles.

Any time you run low on glucose for energy, your body turns to these reserves.

But for every gram of stored glycogen you have in your body, you’ll also find three or four grams of water attached[*].

This is why you lose so much water weight at the beginning of keto. Your body goes through these glycogen stores and that releases all that water from your system.

While you’re not losing fat per se, you will feel slimmer, less bloated, and fit in your clothes better as a result of your body flushing out this extra water.

Here’s the bad news: once all these glycogen stores are purged, your body doesn’t have a way of holding on to water when you’re in the state of ketosis.

Keto dieters are extra prone to dehydration — especially when they’re first starting out — because they’re not used to constantly rehydrating and giving their bodies the water it desperately needs.

What happens when you don’t have enough water?

You become dehydrated, which can lead to[*]:

  • Diarrhea
  • Vomiting
  • Keto headache
  • Keto flu
  • Extreme thirst
  • Fatigue
  • Dizziness and confusion
  • Dark-colored urine
  • Dry skin
  • Dry mouth

Though all of these are serious, that last one is important when you’re dealing with bad breath.

A dry mouth produces less saliva, which is responsible for getting rid of odor-causing bacteria hanging out in your mouth.

If you don’t have enough saliva to eliminate the bad bacteria, they multiply. Similarly, when you don’t give your body water to flush away excess ketones, they build up and stick around in your mouth[*].

Now you see how the situation compounds into chaos for your breath. A byproduct of dehydration while on the keto diet is bad breath. 

How to Overcome Ketone Breath

You’re making amazing strides for your health by being on a keto diet, so don’t let a small issue like bad breath derail your achievements.

How to fix keto breath

Try one or all seven of these ways to tame the beast that is your keto breath and enjoy your healthier lifestyle.

#1. Boost Your Oral Hygiene

Poor oral hygiene isn’t the same as keto breath. But a dirty mouth doesn’t help the situation and makes everything worse.

Besides brushing your teeth twice a day — and maybe after every meal if you can’t stand your keto breath — consider adding these additional dental health practices to your routine:

  • Floss: It’s an inconvenience, but flossing will get rid of small food particles between your teeth which would normally rot there and cause bad breath.
  • Clean Your Tongue: Using a tongue scraper is almost twice as effective at removing bacteria as regular brushing because your tongue is like flypaper for germs[*].
  • Rinse Your Mouth: Use an oral rinse designed for dry mouth. It may contain antibacterial agents and help lubricate your mouth to prevent bad breath and dry mouth all in one.
  • Try Oil Pulling: Oil pulling with coconut oil, which is naturally antibacterial, will attract leftover food particles and bacteria hiding in your mouth. When you spit, you eliminate these and deep-clean your teeth, tongue, and gums.

#2. Recalculate Your Macros

Did you know you should recalculate your macros every time you lose a decent amount of weight or decrease/increase your regular physical activity levels?

Your body quickly adapts, so you’ll need to be one step ahead if you want to lose weight.

Having too much protein in your diet can lead to keto breath by way of excess ammonia.

But so can having too few carbs.

That’s why you’ll need to take a scientific approach and experiment to see which one is at the root of your keto breath.

Try this 3-step process to see if your keto breath improves while staying in ketosis:

  • Recalculate Your Macros: Use the Keto Macro Calculator to make sure you’re in optimal ranges for ketosis and weight loss for your body.
  • Eat Less Protein: Start at the low end of your protein intake and turn to healthy fats like avocados and macadamia nuts before adding more protein to your diet. This simple switch from a high-protein diet to more fat should cut the amount of excess ammonia, which should lead to fresher breath.
  • Increase Your Carb Intake Slowly: If you’re currently at 20 grams of net carbs per day, try bumping up to 25 grams to see if you notice any changes. This should reduce the number of excess ketones so fewer are forced out via bad breath.

If your keto breath goes away but you notice you’re not losing as much weight, you can either cut back the carbs or increase your physical activity to burn off more of what you eat.

If that fails to work, make sure to cross off these 10 reasons why you’re not losing weight on keto.

#3. Drink More Lemon Water

Do you know the old adage about drinking half your weight in ounces of water each day?

While that’s never been scientifically proven, you do need to drink more water when you’re in ketosis. Why? Because your body will not have those glycogen stores to hold onto water like it used to[*].

Besides combating dehydration, water also has another benefit: washing away the ketones on your breath and diluting the smell of those you release in urine.

Water will also keep you from experiencing dry mouth, which amplifies keto breath.

If using the “eight glasses of water a day” rule helps you remember to drink and track your water intake, by all means, keep using it.

Just don’t drink too much water without replenishing your electrolytes or you’ll risk flushing all those away — and that’s a big problem.

Lemon water will not only freshen your breath, but lemons also have antibacterial properties to help kill off lingering odor-causing germs in your mouth[*].

Yo can also add stevia to your lemon water for a carb-free faux lemonade.

#4. Skip Your Standard Mints and Gums

You may have never thought to check the label on the gum you keep in your bag or look up the nutrition facts for the mints you stash at your desk, but you’ll need to when you’re in ketosis.

Mints and gums are often full of sugars and hidden carbs that will kick you out of ketosis faster than you can get back in.

#5. Be Careful With Sugar-Free Alternatives

You may be ditching your usual gum or mints, but that doesn’t mean sugar-free alternatives are a better option.

These are usually packed with sugar alcohols and artificial sweeteners, which are not zero-carb and can both raise your blood sugar and spike your insulin levels[*].

Stay away from anything containing:

  • Sorbitol
  • Maltitol
  • Xylitol
  • Isomalt
  • Aspartame
  • Sucralose
  • Saccharin
  • Mannitol
  • Lactitol
  • Polydextrose
  • Hydrogenated starch hydrolysates

Ingesting these sugar alcohols and sugar alternatives has been associated with increased sugar cravings, migraines, and extreme gastrointestinal discomfort such as[*]:

  • Bloating
  • Cramping
  • Flatulence
  • Diarrhea

There’s a better way to freshen your breath naturally without painful side effects.

#6. Try Natural Breath Fresheners

Before the age of commercially-made mints and gums, the mint plant was the most popular breath-freshener of medieval Europe. People chewed whole leaves to sweeten their breath and mixed the mashed leaves with vinegar to rinse their mouths[*].

These holistic foragers also invited other fragrant herbs and spices to the fresh breath party, including:

  • Parsley
  • Cinnamon
  • Clove
  • Marjoram
  • Cardamom
  • Rosemary
  • Sage
  • Fennel seeds

You can find all-natural extracts of these plants to spray in your mouth at health food stores, but you can also chew on them yourself or add these herbs to your favorite keto recipes.

Feeling extra productive? Create your own homemade mouthwash or breath spray.

Using high quality, food-grade essential oils containing any of those herbs, follow this natural breath freshener recipe:

  1. Grab a spray bottle or mason jar and clean it well.
  2. Add three drops of essential oil of your choice (either one flavor or a combo of flavors) to your container.
  3. Fill the rest of your vessel with ¼ cup vinegar and ½ cup distilled water.
  4. Shake to combine.
  5. Spray in your mouth or take a swig, swish it around, and spit out to get rid of bad breath bacteria.

#7 Check Your Ketone Levels

If you experience fat loss while eating a keto diet, you are probably in ketosis like you should be. But stinky breath could mean elevated ketone levels. 

By checking these levels, you will be able to rule it out and try other things. But if your testing reveals higher levels, then you know what is to blame. 

There are a few different ways to measure ketones: 

  • Blood Testing: This is by far the most reliable and accurate way to find your level of ketosis. There aren’t any factors that can dilute the results. 
  • Urine Strips: These are known to be unreliable because while they might measure ketones at the beginning of your diet, the longer you stay in ketosis, the more your body will use them and a lower amount will show on the testing strips.
  • Breath Testing: After you breathe into a breath ketone meter, it shows an approximate number of ketones in your breath. This is more reliable than urine testing, but it only measures breath acetone, not any other form. 

Follow the tips in this guide and your keto breath will disappear faster than your tax refund. But you should also take comfort in knowing that keto breath is temporary. 

Keto Breath Doesn’t Last Forever

While some keto dieters never experience keto breath, others struggle with it the very first week.

The good news is that ketosis breath eventually goes away and is not a permanent part of following a keto diet.

By combining these techniques and sticking to your ketogenic diet for a few months, your body will naturally adapt to your low-carbohydrate way of eating.

Your body will stop producing so many extra ketones and find a healthy balance around the end of your first fully fat-adapted month. With fewer excess ketones, you’ll have better breath.

Now there’s no reason for abandoning your ketogenic diet — especially if you’ve noticed awesome results thus far.

Another upside to keto breath is the fact that it’s a sign you’re in ketosis. 

While keto breath isn’t sexy, it does mean you’re well on your way to reaching your weight loss and body goals — and that’s definitely worth celebrating.


Join the Internet's largest keto newsletter

We'll send you articles, product guides, and exclusive offers customized to your goals.