If you’re new to a ketogenic high-fat, low-carb diet for weight loss or any other reason, you may have heard that it can cause bad breath or what’s commonly called “keto breath.” You may even have it yourself. The keto breath smell is often described as “fruity,” metallic, or even like nail polish remover. It can be accompanied by a metallic taste. 

But don’t worry, it’s one of the common side effects when starting a ketogenic diet, and not everyone gets keto breath. Those who do, can rest assured that like other “keto flu” symptoms it’s short-lived, and there are some things you can do if you find yourself with ketosis breath. 

What Causes Keto Breath?

You can have good oral hygiene, floss regularly, and still end up with keto breath when you enter a state of ketosis (when your body uses fat as its primary fuel source instead of carbs). Unlike basic bad breath, or halitosis, which is typically due to a build-up of bacteria on the tongue, poor oral hygiene, or both, keto breath is a direct result of your body transitioning from burning carbs for energy to burning fat for energy. In other words, it’s a sign that what you’re doing is working and your ketone levels are rising! 


When your body starts to burn fat for energy instead of glucose, the by-product is ketones. The body produces three kinds of ketones: beta-hydroxybutyrate, acetoacetate, and acetone. The most common cause of keto breath is the third ketone, keto acetone. When you first start producing ketones to replace glucose for fuel, the body often creates more ketones than your body will initially use. So, the body disposes of this overabundance of ketones through the breath (exhalation, hence the smell) and urination. Once your body has no more glucose stores to draw from for energy and starts getting more efficient at using ketones for energy, keto breath typically resolves itself. 

However, there are other reasons for keto breath. 


Not hydrating enough (dry mouth) can influence keto breath, too. The ketogenic diet is a natural diuretic, so it’s not uncommon to become dehydrated when starting a keto lifestyle. 

Consuming Too Much Protein 

A high-protein diet could be a culprit; protein can break down into sulfur compounds and lead to an ammonia smell on the breath. 

How to Help Keto Breath

If you’re not dehydrated or eating too much protein, an acetone smell on your breath is a good indicator that you’re in ketosis. In fact, one of the signs people look for when aiming to achieve ketosis is keto breath. But that happy fact doesn’t make the smell any better. So, what can you do? Plenty!

  • Give it time.
    As we mentioned above, the body will eventually use ketones more efficiently and keto breath should clear up.
  • Hydrate, hydrate, hydrate!
    Not only does drinking water help to prevent bad breath from dehydration, but also it can help to “wash away” the breath acetone, as well as flush out ammonia from protein.
  • Add crushed peppermint or spearmint leaves to your water.
    These natural keto-friendly breath fresheners are like sugar-free mints or mouthwash without the added sweeteners; they’ll help mask any odor and freshen your breath.
  • Track your protein.
    Too much protein contributes to an ammonia smell on the breath. Make sure you’re staying within your macronutrients and eat less protein if necessary. 
  • Slightly increase your carbs.
    Higher carb intake can help. Start by adding on 5 grams per day, being sure to monitor your ketones and glucose (blood sugar) to ensure you stay in ketosis. Slightly increasing carbs may help to counteract the over-abundance of ketones the body initially produces.

The Final Word

Keto breath is temporary and will go away in time, usually within a couple of weeks. Also remember, it’s a good sign that your body is doing what you want it to do on the high-fat dietreaching ketosis and all the amazing health benefits that come along with it. So, keep up the good oral hygiene, flossing, and keto diet, avoid carbohhydrates and stick to healthy fats, and it will pass soon enough. 



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