The Hidden Dangers of Mouth Breathing: How It Affects Your Health

If you’re a parent (or an adult working hard to stay healthy), it’s easy to shrug off mouth breathing as a harmless quirk. In reality, consistently breathing through the mouth can chip away at sleep quality, oral health, facial growth in children, and even day-to-day mood and concentration. The good news is that most people can improve nasal breathing with the right mix of education, simple home strategies, and, when needed, targeted therapy.

What Is Mouth Breathing?

Mouth breathing is exactly what it sounds like: inhaling and exhaling primarily through the mouth instead of the nose. Occasional mouth breathing during a cold or a strenuous workout is normal. The problem is habitual, day-and-night mouth breathing. When air bypasses the nose, it also bypasses the nose’s built-in “air treatment plant,” which warms, filters, and humidifies each breath before it reaches the lungs. That treatment matters more than most of us realize. The nose conditions air, helps regulate airflow, and contributes nitric oxide that supports better oxygen exchange in the lungs (Lundberg, “Nasal nitric oxide in man”).

In children, the stakes are higher. The face and jaws are still growing, sleep patterns are more fragile, and attention and learning hinge on good rest. Habitual mouth breathing can sit at the center of a web of issues that includes snoring, disrupted sleep, selective eating, orthodontic crowding, and daytime behavior concerns. If you’re just starting to explore this topic, our quick primer on early red flags is a helpful place to begin (Breathe First: “Mouth Breathing in Children: Early Signs”).

How Common Is Mouth Breathing?

Researchers estimate that mouth breathing affects a sizeable minority of children, though exact numbers vary depending on the definition and the population studied. Recent reviews place the prevalence between roughly 11% and 56% in children (Lin, “Impact of mouth breathing on dentofacial development”; Zhang, “Adenoid facies: a long-term vicious cycle of mouth breathing”). Pediatric obstructive sleep apnea (OSA), the most severe end of sleep-disordered breathing, affects approximately 1–5% of children, with habitual snoring far more common (American Academy of Pediatrics, “Diagnosis and Management of Childhood Obstructive Sleep Apnea”; Nierengarten, “Use guidelines to diagnose pediatric sleep apnea”).

Adults can also become habitual mouth breathers for many reasons, from chronic nasal congestion to structural narrowing of the nose. While adult prevalence data are less precise, the physiology is similar: more unfiltered air to the throat and lungs, more dryness in the mouth, and more snoring risk when the jaw relaxes at night.

How Nasal Breathing Works (And Why It’s Better)

Nasal breathing recruits a sophisticated system designed to prepare each breath before it hits the lungs. Inside the nose, turbinates swirl air to increase its contact with moist mucosa, cilia sweep particles toward the throat to be swallowed, and mucus traps dust and pathogens. The paranasal sinuses and nasal mucosa generate nitric oxide (NO), which mixes into inhaled air and can help widen the pulmonary blood vessels, supporting oxygen uptake (Lundberg, “Nasal nitric oxide in man”; Lundberg, “Nitric Oxide and the Paranasal Sinuses”).

There’s also a water and energy story. Breathing out through the mouth leads to greater water loss compared with nasal breathing. In a controlled study of healthy adults, switching from nasal to oral expiration increased respiratory water loss by about 42% during quiet breathing (Svensson, “Increased net water loss by oral compared to nasal expiration in healthy subjects”). More water loss means drier mucosa, thirstier nights, and a parched mouth in the morning. Over time, a dry mouth sets the stage for dental issues.

Why Chronic Mouth Breathing Matters

Oral and dental health.

Saliva is nature’s mouthwash. It neutralizes acids, supplies minerals to protect enamel, and keeps oral bacteria in balance. Habitual mouth breathing dries out the mouth and can tilt that balance toward cavities and gum disease. Patients with chronic dry mouth (xerostomia) face higher caries risk and often experience gingival inflammation and halitosis (ADA, “Xerostomia (Dry Mouth)”; Plemons, “Managing xerostomia and salivary gland hypofunction”). In children, multiple studies associate mouth breathing with worse dental status and more halitosis (Motta, “Association between halitosis and mouth breathing in children”; Alqutami, “Dental health and halitosis in 10–15-year-olds”). A 2025 systematic review concludes that mouth-breathing children show higher rates of caries and periodontal inflammation than nasal-breathing peers (International Journal of Paediatric Dentistry, “Dental caries and periodontal outcomes in mouth-breathing children and adolescents”).

Sleep and behaviour.

Mouth breathing increases the odds of snoring and sleep-disordered breathing. The American Academy of Paediatrics advises that children who snore regularly should be evaluated for OSA because poor sleep is linked with behaviour problems, inattention, and learning difficulties (AAP Guideline, Marcus et al.). In the landmark CHAT trial, early adenotonsillectomy improved behaviour, symptoms, and quality of life for children with OSA compared with watchful waiting (Marcus et al., “A Randomized Trial of Adenotonsillectomy”; Magnusdottir, “Results from the Childhood Adenotonsillectomy Trial (CHAT)”). A more recent JAMA analysis found that surgery for mild OSA also led to meaningful improvements in behavior and symptoms even when some primary cognitive measures did not change (Redline, “Adenotonsillectomy for Snoring and Mild Sleep Apnea in Children”).

Facial growth and airway development. When the mouth hangs open at rest, the tongue tends to sit low in the mouth. Over time, that posture can influence how the upper jaw widens and how the lower jaw rotates during growth. High-quality reviews associate mouth breathing with narrower dental arches, longer lower facial height, and altered jaw posture on cephalometric analysis (Zhao et al., “Effects of mouth breathing on facial skeletal development in children: a systematic review and meta-analysis”; Lin, Frontiers in Public Health). This is an association rather than a simple cause-and-effect rule, but the pattern is consistent across many studies.

Energy, stamina, and comfort. Nasal breathing is more efficient at rest and during submaximal effort for many people because it favors better diaphragmatic mechanics and humidified air. Some experimental studies suggest oral breathing drives higher minute ventilation at a given workload and can feel more taxing, while nasal strategies can sustain similar oxygen uptake with calmer respiration (Mapelli, “Nasal vs oral breathing in healthy adults”). If exercise leaves you with a burning throat and a dry mouth, a focus on nasal breathing and nasal hygiene can help.

Benefits of Nasal Breathing for Overall Health

Nasal breathing is not just “nicer.” It is measurably different in ways that help sleep, oral health, and daytime performance.

Better oxygenation and airway comfort. Nitric oxide from the paranasal sinuses mixes into inhaled air during nasal breathing and can support better matching of ventilation and perfusion in the lungs (Lundberg, Acta Physiol Scand review; Cardell, “The Paranasal Sinuses and a Unique Role in Airway Nitric Oxide”). Many people describe calmer, deeper breathing and less throat irritation when they keep air flowing through the nose.

Moisture conservation and less dry mouth. Compared with nasal breathing, mouth breathing increases respiratory water loss and can leave mucosal tissues parched (Svensson, Rhinology). In practical terms, that means fewer overnight awakenings for water and less morning stickiness in the mouth when you keep your lips sealed.

Oral health protection. Saliva works best when the mouth remains closed at rest. Nasal breathing reduces nighttime dryness and helps maintain the salivary film that protects against enamel erosion and bacterial overgrowth (ADA, Xerostomia). For kids, that can mean fewer fillings over the long haul.

Sleep quality. Nasal breathing reduces vibration and collapse in the soft tissues of the throat for many people, lowering snoring and sleep fragmentation. While not a cure for every case, it’s a foundational habit to support any sleep-disordered breathing care plan (AAP, Guideline).

Mouth Breathing vs. Nasal Breathing

What to know fast: Habitual mouth breathing in kids is common and linked with snoring, sleep problems, and changes in facial growth (Lin, Frontiers; Zhao, BMC Oral Health). Nasal breathing filters, warms, and humidifies air and provides nitric oxide that supports oxygen uptake (Lundberg, Acta Physiol Scand). Dry mouth from open-mouth sleep increases cavity and gum-disease risk (ADA, Xerostomia). If your child snores most nights or breathes through the mouth, the AAP recommends evaluation because treatment can improve behaviour, symptoms, and quality of life (AAP, Guideline; NEJM CHAT, Marcus et al.). Myofunctional therapy and breathing re-education can complement medical care and improve OSA severity in select patients (Camacho, Sleep meta-analysis).

Common Causes of Mouth Breathing

Allergies and chronic nasal congestion. Allergic rhinitis inflames the nasal lining, narrows airflow, and makes the mouth an easy shortcut. Over time, the “I’ll just open my mouth” reflex becomes a default habit. Treating the underlying allergy, rinsing with saline, and practicing gentle nasal breathing exercises can help. Small clinical studies suggest breathing exercises may complement medical therapy for allergic rhinitis by improving perceived nasal airflow, though results are mixed and more rigorous research is needed (Nair, “Nasal breathing exercise and AR”; Courtney, “Functional Nasal Breathing Rehabilitation”).

Enlarged adenoids or tonsils. In children, big adenoids and tonsils are common. They can block the nose or upper throat during sleep, prompting mouth breathing and snoring. When medical therapy fails and sleep is disrupted, an ENT assessment is appropriate. Surgery is not automatically required, but for the right child, removing enlarged adenoids and/or tonsils can improve sleep and daytime functioning (NEJM CHAT, Marcus et al.; JAMA, Redline et al.).

Habit and posture. Even once noses are clear, the body can cling to the mouth-open pattern. Low tongue posture, forward-head posture, and lips apart at rest are classic signs. Myofunctional therapy helps here by retraining the tongue and lips and building the stamina to keep the mouth closed comfortably (Breathe First: “How Myofunctional Therapy Helps Correct Mouth Breathing”).

Structural or functional nasal narrowing. Deviated septum, small nostrils, nasal valve collapse, and turbinate hypertrophy all make nasal breathing harder. Medical therapy and nasal hygiene can make a big difference for many. Some will benefit from procedures that restore nasal airflow.

The Hidden Dangers of Mouth Breathing

1) Oral Health: Cavities, Gum Inflammation, and Halitosis

A persistently open mouth dries out the oral tissues and lowers saliva volume. With less saliva, acids linger longer and bacteria flourish. The ADA and JADA note that xerostomia significantly raises risk for cavities, demineralization, and periodontal disease (ADA, “Xerostomia”; Plemons, JADA). In children, mouth breathing has been linked with worse gingival status and more halitosis, especially in those with chronic nasal blockage (Motta, halitosis association study; Alqutami, paediatric dental status). A 2025 systematic review emphasizes higher caries and periodontal inflammation in mouth-breathing children (International Journal of Paediatric Dentistry, “Dental caries and periodontal outcomes…”).

Practical takeaway: keep lips gently sealed at rest, encourage water over sweet drinks, and schedule regular dental check-ups. If your child often wakes with a dry mouth or bad breath, that’s a useful clue to investigate breathing patterns and sleep.

2) Sleep Quality, Snoring, and Sleep-Disordered Breathing

Mouth breathing and snoring frequently travel together. When the jaw falls open during sleep, the tongue and soft palate shift backward and narrow the airway. The AAP guideline recommends that children who snore most nights undergo evaluation, because treatment improves symptoms and daytime function (AAP, “Diagnosis and Management…”). In mild paediatric OSA, adenotonsillectomy improves behaviour and quality of life for many children, even if formal attention testing does not always show large gains (Redline, JAMA 2023).

For adults and teens, addressing nasal obstruction, building nasal breathing skills, and improving sleep habits are essential. In established OSA, CPAP remains the gold standard. Adjuncts like custom dental appliances or myofunctional therapy can be helpful when matched to the patient’s pattern (Camacho, Sleep meta-analysis; J Clin Sleep Med, “Tongue motor skills and myofunctional therapy: systematic review”).

3) Facial Development and Posture in Children

Children who breathe habitually through the mouth are more likely to show narrower dental arches, longer faces, and backward rotation of the mandible in cephalometric studies (Zhao et al., BMC Oral Health). While genetics and other habits also matter, the tongue resting on the palate is a powerful natural “expander.” When the tongue sits low and forward, it no longer provides that gentle outward pressure on the upper jaw, and the airway can develop more narrowly (Lin, Frontiers). Myofunctional therapy aims to restore tongue posture and lip seal, which supports growth-friendly forces while the face is developing (Breathe First: Myofunctional Therapy).

4) Mood, Attention, and Daytime Function

Children with sleep-disordered breathing are more likely to struggle with behaviour and attention. Reviews show consistent associations between poor sleep and neurobehavioral problems in childhood (Trosman, “Cognitive and Behavioural Consequences of SDB”; Brockmann, “Neurocognitive Consequences in Children with SDB”). Improvements in sleep quality after treatment often lead to better behaviour scores and daytime functioning (Marcus et al., CHAT; Smith, ERJ 2016). If your child is bright but struggling to focus, ask specific sleep questions before assuming it’s “just” attention.

Recognizing the Signs in Children

What you might see: lips apart at rest, frequent mouth-open photos, snoring or noisy breathing in sleep, chronic chapped lips, morning thirst, bad breath, “long face” appearance, and under-the-eye dark circles. Teachers may report daydreaming, irritability, or trouble staying on task. Paediatric dentists may spot a high-arched palate, narrow dental arches, or crowding early (Breathe First: Early Signs).

Simple home observations help. Watch your child when they’re quietly absorbed in a game. Are their lips together? Is the tongue resting gently on the roof of the mouth? Do they wake up rested without a dry mouth? If not, it’s time to explore solutions.

Practical Home Strategies to Encourage Nasal Breathing

Make the nose happy. Use a gentle saline rinse or spray at bath time and before bed to clear pollen and dust. A brief, warm shower before sleep also helps open the nose. If allergies are the culprit, work with your GP to optimize medical therapy. Once the nose feels open, nasal breathing becomes far easier.

Practice short, playful drills. Kids respond to games. Try “quiet mouse breathing” (lips together, nose only) for short intervals while reading or playing. Practice a “tongue parachute” position: tip to the spot behind the top front teeth, then the whole tongue resting on the palate. These micro-reps build strength and familiarity. You’ll find a step-by-step starter set here (Breathe First: Myofunctional Exercises).

Support the lips. Encourage relaxed lip seal during screen time, homework, or car rides. A small sticker reminder on the tablet or mirror can cue “lips together, breathe through the nose.” Some families use a child-safe chewy tube or a myofunctional tool to build lip strength under guidance. The right tool used consistently can reinforce new patterns (Breathe First: Myo Munchee Mini).

Build a sleep-friendly routine. Keep regular bedtimes, use a cool-mist humidifier if the bedroom is dry, and consider hypoallergenic pillow covers. If snoring or gasping continues, ask your GP or dentist for a referral to a sleep clinic.

A word on mouth taping. You may have seen mouth taping on social media. Professional sleep organizations urge caution, noting limited evidence and potential risks for people with nasal blockage or undiagnosed sleep apnea (AASM, “Viral TikTok trends are not the answer for better sleep”). One small study in mild OSA suggested a drop in AHI with mouth tape, but such interventions should only be considered with clinician guidance after ruling out contraindications (Lee, “Impact of Mouth-Taping in Mouth-Breathers with Mild OSA”). At Breathe First we prioritize opening the nose, retraining tongue and lip posture, and addressing root causes before any taping is discussed.

Where Myofunctional Therapy Fits

Myofunctional therapy is like physiotherapy for the mouth, tongue, and face. Exercises target lip seal, tongue posture, nasal breathing, and swallowing patterns. For motivated families, it provides a structured path to rebuild healthy habits and, importantly, to keep them going.

Evidence is growing that myofunctional therapy can reduce OSA severity and snoring in select patients and improve daytime symptoms, especially when combined with other treatments. In a meta-analysis of oropharyngeal exercises, adults with OSA saw the apnea-hypopnea index fall by roughly 50%, while children improved by about 62% (Camacho, “Myofunctional Therapy to Treat Obstructive Sleep Apnea”). Systematic reviews continue to refine which patients benefit most and how programs should be structured (J Clin Sleep Med, “Assessment and rehabilitation of tongue motor skills…”). Myofunctional therapy is not a substitute for medical care, but it is a powerful adjunct within a team approach.

If you’re curious how a personalized plan looks, we outline the process and common milestones here (Breathe First: Myofunctional Therapy) and discuss how therapy supports the transition from mouth breathing to easy, automatic nasal breathing here (Breathe First: How MT Helps Correct Mouth Breathing).

Breathing Re-education and Nasal Techniques

Breathing re-education focuses on gentler, nasal-first breathing with relaxed diaphragmatic mechanics. Programs inspired by the Buteyko method are popular and emphasize nasal breathing, reduced-volume breathing, and breath-hold drills to build CO₂ tolerance. Clinical trials in asthma suggest improved symptom control and reduced medication use for some patients, though effects on lung function have been mixed and the evidence base remains modest (Vagedes, European Journal of Medical Research 2024; Slader, Thorax 2006; Australian Health Dept Evidence Evaluation, 2024 report). For nasal congestion relief, simple humming, gentle nasal breathing drills, and saline irrigation can be helpful as part of a larger plan. We integrate these elements case-by-case (Breathe First: Research).

What an Evidence-Based Care Pathway Looks Like

Step 1: Screen and observe. If your child snores most nights, wakes unrefreshed, or shows daytime behaviour concerns, bring it up with your GP or paediatric dentist. Note mouth-open rest posture, dry lips, and morning thirst. Our practical checklists make it easier to spot patterns early (Breathe First: Practical Guides).

Step 2: Clear the nose and treat allergies. Optimizing nasal airflow makes every next step easier. Combine environmental controls with medical management if allergies are part of the picture.

Step 3: ENT and sleep evaluation when indicated. If snoring is habitual or there are pauses in breathing, an ENT exam and, when appropriate, a sleep study provide clarity. The AAP guideline remains the touchstone here (AAP, 2012 guideline).

Step 4: Myofunctional therapy and habit re-education. Build lip seal, tongue posture, and nasal competency with expert guidance. This step compliments orthodontic care and sleep interventions rather than competing with them (Breathe First: Myofunctional Therapy).

Step 5: Orthodontic and dental coordination. Early expansion or interceptive orthodontics may be part of care in some children with narrow arches and persistent crowding. Good oral hygiene, fluoride guidance, and caries risk assessment protect teeth while breathing improves (ADA, Caries Risk Assessment).

Frequently Asked Questions

When to Seek Prompt Professional Help

Talk to your GP, paediatrician, or dentist promptly if your child shows any of the following: loud nightly snoring, witnessed pauses in breathing, choking or gasping during sleep, bedwetting re-emerging after toilet training, morning headaches, growth faltering, or significant daytime behaviour changes. These can be signs of sleep-disordered breathing that deserve a structured evaluation (AAP, Guideline; AAPD Policy, “Policy on Paediatric OSA”).

How Breathe First Can Help

At Breathe First, we assess breathing patterns, oral posture, and sleep clues, then build a simple, family-friendly plan. That plan might combine nasal hygiene, allergy coordination with your GP, myofunctional therapy, habit re-education, and practical tools. Explore our overview of therapy (Myofunctional Therapy), learn how targeted exercises shift mouth to nose breathing (How MT Helps Correct Mouth Breathing), or start with our early-signs checklist (Early Signs Parents Should Know). If you’re ready to take the next step, book a consultation and we’ll tailor a plan to your family.

In Summary

Mouth breathing is common, but it isn’t benign. For children, it can alter sleep, learning, and facial growth. For adults, it can erode sleep quality and oral health. The core solution is simple in concept: open the nose, strengthen tongue and lip function, and make nasal breathing feel easy again. With a practical plan and the right team, most families see steady progress within weeks and meaningful results over a few months.

Sources

Throughout this article we’ve linked the author/title of key references in context. For convenience, here is a consolidated list of those sources as clickable citations:

1. Lundberg J. O. N., et al., “Nasal nitric oxide in man.” Acta Physiol Scand review.
2. Lundberg J. O. N., “Nitric Oxide and the Paranasal Sinuses.” The Anatomical Record.
3. Svensson S., Olin A.-C., Hellgren J., “Increased net water loss by oral compared to nasal expiration.” Rhinology.
4. Lin L., et al., “Impact of mouth breathing on dentofacial development.” Frontiers in Public Health.
5. Zhao Z., et al., “Effects of mouth breathing on facial skeletal development in children: a systematic review and meta-analysis.” BMC Oral Health.
6. Motta L. J., et al., “Association between halitosis and mouth breathing in children.” Clinics (Sao Paulo).
7. Alqutami J., et al., “Dental health, gingival status, and halitosis in mouth-breathing children.” J Clin Exp Dent.
8. International Journal of Paediatric Dentistry, “Dental caries and periodontal outcomes in mouth-breathing children and adolescents.” Systematic review (2025).
9. American Academy of Pediatrics, Marcus C., et al., “Diagnosis and Management of Childhood Obstructive Sleep Apnea.” Pediatrics.
10. Marcus C., et al., “A Randomized Trial of Adenotonsillectomy for Childhood Sleep Apnea” (CHAT). New England Journal of Medicine.
11. Redline S., et al., “Adenotonsillectomy for Snoring and Mild Sleep Apnea in Children.” JAMA.
12. Trosman I., et al., “Cognitive and Behavioral Consequences of Sleep-Disordered Breathing in Children.” Children (MDPI) review.
13. Camacho M., et al., “Myofunctional Therapy to Treat Obstructive Sleep Apnea: Systematic Review and Meta-analysis.” Sleep.
14. J Clin Sleep Med, “Assessment and rehabilitation of tongue motor skills with myofunctional therapy in OSA: systematic review and meta-analysis.”
15. ADA, “Xerostomia (Dry Mouth).”
16. Plemons J. M., et al., “Managing xerostomia and salivary gland hypofunction.” JADA.
17. AAPD, “Policy on Pediatric Obstructive Sleep Apnea.”
18. Mapelli M., et al., “Nasal vs. oral breathing during submaximal exercise in healthy adults.” PLOS ONE (2025).
19. Nair S., et al., “Nasal breathing exercise and allergic rhinitis symptoms.” Indian J Otolaryngol Head Neck Surg.
20. Courtney R., “Functional Nasal Breathing Rehabilitation.” Aeronautics (MDPI).
21. AASM, “Viral TikTok trends are not the answer for better sleep.”
22. Lee Y.-C., et al., “Impact of mouth-taping in mouth-breathers with mild OSA.” Healthcare (Basel).
23. Zhang J., et al., “Adenoid facies: a long-term vicious cycle of mouth breathing.” Frontiers in Public Health.
24. Frontiers in Sleep, “Mouth-breathing phenotype and pediatric OSA.”
25. Dental XLNC, “The Hidden Dangers of Mouth Breathing.” (original external source referenced in your draft).
26. ADA, “Caries Risk Assessment and Management.”
27. Holden W. E., et al., “Greater nasal nitric oxide output during inhalation.” BMC Pulmonary Medicine.

Helpful Internal Resources from Breathe First

• Mouth Breathing in Children: Early Signs Parents Should Know
• How Mouth Breathing Affects Sleep, Behaviour, and Learning
• How Myofunctional Therapy Helps Correct Mouth Breathing
• Myofunctional Therapy: What to Expect
• Starter Myofunctional Exercises
• Myo Munchee Mini (tool for developing oral muscle tone)
• Our Research Round-Ups
• Practical Guides for Parents

Friendly reminder: Information here is educational and does not replace advice from your healthcare provider. If you suspect sleep-disordered breathing, please seek a qualified evaluation.