How does mouth breathing affect your teeth and gums?

Breathing through your mouth, especially for hours at night, dries out the saliva that protects your teeth and gums. Studies link mouth breathing to a more acidic mouth during sleep, more plaque and more gum bleeding, and in children to some kinds of cavities. The research shows these things go together, but it's mostly too limited to prove mouth breathing causes them on its own.

How does mouth breathing affect your teeth?

Mouth breathing dries out saliva, which is the mouth's built-in protection for teeth and gums. The American Dental Association describes several jobs it does, including cleaning the mouth, protecting teeth and gums against physical damage and bacteria, and keeping the pH near neutral. It also helps clear sugar from the mouth and buffers acids from food or from the stomach. A healthy person makes somewhere between half a litre and a litre and a half of it a day.

When saliva flow drops, those protections weaken. The ADA says reduced saliva can increase the chance of cavities, demineralization of teeth, tooth sensitivity and oral infections. It lists plaque buildup, gingivitis and periodontitis among the things dentists commonly find in people with dry mouth. The ADA's consumer site puts it simply: saliva is the mouth's primary defense against tooth decay.

Night is already the low point. According to the ADA, saliva output reaches its lowest levels during sleep, and mouth breathing can make dry mouth worse at night.

Does mouth breathing make your mouth more acidic?

One small study measured this directly. In 2016, researchers in New Zealand fitted 10 healthy adults with a device that recorded pH behind the upper front teeth over several nights. On some nights participants wore a nose clip to force them to breathe through their mouths.

During the day, the mean pH was 7.3. During normal sleep, it was 7.0. During sleep with mouth breathing, it was 6.6, a statistically significant drop. The pH drifted down slowly over the night in everyone, but it fell further and stayed low for longer when people breathed through their mouths. The authors noted that this drop has been proposed as a factor in tooth erosion and cavities.

That study had only 10 people, and a nose clip isn't the same as natural mouth breathing. It's useful as a measurement of what happens, not as proof of long-term damage.

Does mouth breathing cause cavities and gum disease?

Most of the research on dental outcomes is in children and teenagers.

A 2025 systematic review in the International Journal of Paediatric Dentistry looked at 11 cross-sectional studies. Young people who breathed through their mouths had more gum bleeding, more plaque and more gum changes than those who didn't. For cavities, the review found limited evidence of a link, confined to early lesions and advanced ones.

One of the studies in this area, from Brazil, looked at 257 children aged 3 to 5. Those who mainly breathed through their mouths had a higher prevalence of cavities in their front teeth. In the same study, frequent sugar intake was an even stronger factor, which is a reminder that diet plays a big part.

Cross-sectional studies capture one moment in time. They can show that mouth breathing and gum problems tend to occur together, but not which came first or whether something else explains both. Research in adults is thinner still.

If you're worried about a child who breathes through their mouth, raise it with their dentist or doctor, and see mouth breathing in children. This article is aimed at adults.

How do you know if you breathe through your mouth at night?

Most people find out they breathe through their mouth at night from the clues it leaves, since they're asleep when it happens. Cleveland Clinic says your first sign may be the combination of a dry mouth, bad breath and drool on your pillow in the morning. Snoring is another common one, and a bed partner may notice your mouth hanging open.

A healthcare provider can check more formally. Cleveland Clinic describes a lip seal test, which checks whether you can breathe with your mouth closed, and a mirror test, where a mirror held under your nose clouds up if you're breathing through it. Our two-minute nose test is a home version of the same idea.

What else dries out your mouth at night?

Mouth breathing isn't the only cause, and it's worth ruling out the others. The ADA says the most frequent cause of reduced saliva is medication. It lists antihistamines, decongestants, blood pressure medicines, pain medicines, diuretics, muscle relaxants, GLP-1 drugs and antidepressants among those that can contribute, and notes that taking several medicines raises the risk.

Lifestyle plays a part too. The ADA names alcohol, tobacco, cannabis, a lot of caffeine and spicy food as possible causes. It estimates that about 22% of people worldwide have dry mouth, and that it becomes more common with age.

There's an overlap worth noticing. Allergy and cold medicines can dry the mouth, and the blocked nose they're treating can push you into mouth breathing. If that sounds like you, ask a pharmacist which options are least drying. Why do I wake up with a dry mouth? goes through the causes in more detail.

What can you do to protect your teeth?

To protect your teeth, start with the basics, since they work whatever the cause:

1. Brush gently at least twice a day with fluoride toothpaste, and floss every day.
2. Drink water through the day, and keep some by the bed.
3. See your dentist at least twice a year, and tell them if you often wake with a dry mouth so they can factor it into your checkups. For people with dry mouth, the ADA notes that a dentist may suggest a prescription-strength fluoride gel.
4. Ask your dentist about products for dry mouth. The ADA notes that sugar-free gum or candy stimulates saliva, and that artificial saliva and oral rinses can replace moisture.

The ADA's list of coping strategies for dry mouth also includes running a humidifier at night, using lip balm often, and avoiding alcohol-based mouthwash, tobacco and caffeine. It's honest that a 2011 Cochrane review found no strong evidence that any particular spray, gel, lozenge or gum relieves dry mouth symptoms, so it's worth trying a few and seeing what you prefer.

Then look at why you breathe through your mouth. A blocked nose is a common reason, and it's worth sorting out first. Nasal vs. mouth breathing explains the difference. Mouth breathing also dries the mouth in a way that affects breath, which does mouth breathing cause bad breath? goes into.

Where does mouth tape fit in?

If your nose is clear and your mouth just falls open at night, mouth tape is the most direct way to keep your lips closed so you breathe through your nose instead. That's the reverse of the forced mouth breathing that made the mouth more acidic in the 2016 pH study. How to start mouth taping walks through the first nights.

To be clear about the evidence, nobody has tested mouth tape for teeth or gums, so treat it as a practical habit rather than a dental treatment. A 2025 systematic review of mouth taping found the research overall was small and of poor quality. It also lists asphyxiation as a potential risk when the nose is obstructed, so take the two-minute nose test first and leave the tape off whenever your nose is blocked.

If your nose feels a bit narrow rather than blocked, a nasal strip can help. A 2016 meta-analysis found nasal dilators improve nasal breathing, and you can wear a strip and tape together. If your lips get dry, lip balm and mouth tape covers how to use both without losing the seal.

If you snore loudly, or someone has noticed you gasp or stop breathing in your sleep, see a doctor before trying anything else.

If you want to try mouth tape, our pick is the Titan Bamboo Silk Mouth Tape.

* This content is for informational and educational purposes only and is not medical advice. It is not intended to diagnose, treat, cure or prevent any disease or health condition. Talk to a qualified healthcare provider about your health.