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Mouth Breathing: Causes, Effects on Your Mouth and What Helps

Breathing through your mouth, especially at night, can dry your mouth and may affect your gums and teeth. Here is what causes it, when it matters in children, and what helps.

Updated September 2026·By the OHA editorial team·8 min read·How we write
Key takeaways
  • Breathing through your mouth often happens when your nose is blocked, for example by a cold or allergies, or in children by large adenoids or tonsils.
  • The NHS lists breathing through your mouth at night as one of the main causes of a dry mouth, and a dry mouth raises the risk of tooth decay and bad breath.
  • Studies in children link mouth breathing with more plaque and gum inflammation, but the evidence is limited.
  • In a child, snoring with mouth breathing, gasping or restless sleep over a long period can be a sign of obstructive sleep apnoea. See a GP.
  • Taping your mouth shut at night is not a proven treatment. The American Academy of Sleep Medicine calls it a dangerous trend.

A 2022 review in Frontiers in Public Health calls mouth breathing one of the most common harmful mouth habits in children, with estimates of how many children do it ranging from 11% to 56%. The NHS links breathing through your mouth at night with a dry mouth, which matters because saliva helps protect your teeth from decay, as healthdirect Australia explains.

What causes mouth breathing?

  • A blocked nose. The NHS says mouth breathing at night can happen if you have a blocked nose or sleep with your mouth open. The Raising Children Network (Australia) says a cold, allergies or hay fever can block a child's nose. The NHS lists a blocked nose as a symptom of allergic rhinitis, an allergy affecting the nose, for example to pollen, house dust mites, pet hair or mould. The 2022 review adds sinusitis and nose shape problems, such as a bent septum (the wall between the nostrils) or nasal polyps.
  • Large adenoids or tonsils. The adenoids are small lumps of tissue at the back of the nose. The NHS says that when they are enlarged, they can make it hard to breathe through the nose, causing mouth breathing or snoring. The 2022 review calls enlarged adenoids and tonsils the most common cause in children.
  • Habit. The same review says mouth breathing can carry on as a habit after a blockage has been removed.
  • Your mouth falling open in sleep. The NHS lists this as one cause of snoring.

How can it affect your mouth?

A dry mouth

healthdirect lists snoring as a risk factor for a dry mouth, and says a dry mouth greatly increases the chance of tooth decay or gum disease. See dry mouth.

Bad breath

The American Dental Association (ADA) says a dry mouth can be caused simply by breathing through your mouth, and that without enough saliva the mouth is not cleaned as well, which can lead to bad breath. healthdirect says children who mouth-breathe because of large adenoids may have a dry mouth or bad breath. See bad breath.

Gums and tooth decay

Here the evidence is limited. A 2025 systematic review (a study that pulls together the research on a question) looked at 11 studies of children and teenagers. Those who breathed through their mouth had more gum bleeding, more plaque (the sticky film of bacteria on teeth) and more gum changes. The reviewers concluded that mouth breathing might be linked to gum problems and plaque, and that only limited evidence links it with tooth decay. All 11 studies looked at children at a single point in time, so they cannot show that mouth breathing causes these problems.

The 2022 review says air through the mouth dries the saliva, but that how mouth breathing affects decay and gum health is not yet clear, and other factors may be involved. See gum disease and tooth decay.

Does it change how a child's face and teeth grow?

The 2022 review says this has been debated for more than 100 years, studies disagree, and there is no high-quality evidence either way. If you are worried about how your child's teeth are lining up, ask your dentist. See braces and aligners.

Mouth breathing in children

The Raising Children Network says many children snore and in most cases you do not need to worry. Tonsils and adenoids start to grow in the first few months of life, so snoring is common in young children, and fewer children snore by about 9 years old. healthdirect says the adenoids are biggest at around 3 to 5 years and usually gone by the teenage years.

But the Raising Children Network says long-term snoring might be a sign of obstructive sleep apnoea (where the airway narrows or closes during sleep, so breathing stops and starts), especially if your child also breathes through their mouth or seems to gasp, choke or struggle for breath. The US National Heart, Lung, and Blood Institute (NHLBI) lists these signs:

  • at night: snoring, mouth breathing, breathing that stops and starts, waking often and bedwetting
  • in the day: being overactive or aggressive, trouble paying attention at school, a dry mouth or headache in the morning, and sleepiness

healthdirect says that, if significant and untreated, sleep apnoea may affect a child's growth and development.

What might the GP do?

The Raising Children Network says the GP will look at your child's tonsils and may refer them to an ear, nose and throat (ENT) specialist, or suggest an overnight test of their oxygen levels. If a blocked nose is the cause, the GP might suggest a steroid nasal spray.

Many children do not need surgery. healthdirect says enlarged adenoids rarely need treatment because they usually shrink, and the NHS says a doctor may suggest waiting. The Better Health Channel (Victoria) says 2 out of 3 children with mild sleep apnoea get better over 6 months without surgery. It says removing the tonsils may be considered if a child usually breathes noisily in their sleep and has at least 2 related problems, one of which is persistent daytime mouth breathing.

What helps?

What helps depends on the cause.

  • Treat a blocked nose. For allergic rhinitis, the NHS suggests avoiding your triggers, and says a pharmacist can advise on antihistamines, steroid nasal sprays and saltwater rinses. It warns not to use decongestant sprays for more than 5 days, as they can make a blocked nose worse, and not to give decongestants to children under 6.
  • Ease a dry mouth. healthdirect suggests trying to breathe through your nose, using a bedroom humidifier and moisturising your lips. The NHS suggests keeping water by your bed.
  • Protect your teeth. The NHS advises brushing twice a day. The Australian Dental Association suggests cleaning between your teeth daily and regular check-ups, perhaps more often if your mouth is dry.
  • Get snoring checked. If you snore and feel sleepy in the day, or your breathing stops and starts, see a GP. Treatments for sleep apnoea include CPAP (a machine that blows air through a mask) and mouth devices for snoring and sleep apnoea.

Chin straps and mouth shields

The sources disagree. For snoring caused by your mouth falling open, the NHS lists a chin strap to hold your mouth closed, or a vestibular shield, a device worn in the mouth that makes you breathe through your nose. The Better Health Channel says chin straps are not useful for snoring, although its page was last reviewed in 2014. The NHS advises talking to a doctor about the best snoring treatment for you.

What about mouth taping?

Taping the lips shut at night has spread on social media. In a 2023 statement, the American Academy of Sleep Medicine (AASM) listed mouth taping among unproven sleep trends and called it a "dangerous" trend. A 2025 systematic review in PLOS One found only 10 studies, with 213 people in total. Two showed some improvement in measures of sleep apnoea; others found no difference, and some described risks, including suffocation if the nose is blocked. The reviewers concluded there is a potentially serious risk of harm for people who try it indiscriminately, and that more research is needed. If you are thinking about it, see a GP first, so that a blocked nose or sleep apnoea is not missed.

When to see a GP or dentist
  • Your child snores over a long period with mouth breathing, gasping or restless sleep, seems more tired than usual or falls asleep in the day, or is still snoring at 12 (Raising Children Network).
  • Your breathing stops and starts while you sleep, you make gasping or choking noises, or you always feel very tired in the day (NHS).
  • A blocked nose or allergy symptoms are affecting your sleep and everyday life (NHS).
  • Your mouth is still dry after a few weeks of home or pharmacy treatments, or it is painful, red, swollen or bleeding (NHS).
  • See a dentist regularly. The Australian Dental Association says people with a dry mouth may need to go more often.

Frequently asked questions

Is mouth breathing bad for your teeth?

It can dry your mouth, and a dry mouth makes tooth decay more likely. Studies in children also link mouth breathing with more plaque and gum inflammation, though the evidence is limited.

Should I tape my mouth shut at night?

There is no good evidence that it helps, and a 2025 review found a possible risk of serious harm, especially if your nose is blocked. See a GP about snoring or mouth breathing instead.

Will my child grow out of mouth breathing?

Often the cause improves: healthdirect says the adenoids usually shrink and are gone by the teenage years. But see a GP if your child also snores, gasps or seems tired in the day.

Sources

  1. Dry mouth, NHS, accessed September 2026
  2. Snoring, NHS, accessed September 2026
  3. Sleep apnoea, NHS, accessed September 2026
  4. Allergic rhinitis, NHS, accessed September 2026
  5. Adenoidectomy, NHS, accessed September 2026
  6. Dry mouth syndrome, healthdirect Australia, accessed September 2026
  7. Adenoids, healthdirect Australia, accessed September 2026
  8. Sleep apnoea, Better Health Channel (Victoria), accessed September 2026
  9. Snoring, Better Health Channel (Victoria), accessed September 2026
  10. Snoring in babies, kids and teens, Raising Children Network, accessed September 2026
  11. Dry mouth, Australian Dental Association, accessed September 2026
  12. Bad breath, American Dental Association (MouthHealthy), accessed September 2026
  13. Sleep apnea in children, NIH National Heart, Lung, and Blood Institute, accessed September 2026
  14. Viral TikTok trends are not the answer for better sleep, American Academy of Sleep Medicine, 2023, accessed September 2026
  15. Breaking social media fads and uncovering the safety and efficacy of mouth taping in patients with mouth breathing, sleep disordered breathing, or obstructive sleep apnea: a systematic review, Rhee and others, PLOS One, 2025, accessed September 2026
  16. Dental caries and periodontal outcomes in mouth-breathing children and adolescents: a systematic review, Kimura and others, International Journal of Paediatric Dentistry, 2025, accessed September 2026
  17. The impact of mouth breathing on dentofacial development: a concise review, Lin and others, Frontiers in Public Health, 2022, accessed September 2026

This article is general information about oral health. It is not a diagnosis or a substitute for advice from a dentist or doctor who knows your situation. If you have pain, swelling, bleeding that does not settle, or a problem that is getting worse, see a dental professional. In an emergency, contact your local emergency service.

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