Mouth Breathing: Causes, Effects and How to Stop It

Quick answer

Find out why the nose is blocked, then treat that

Habitual mouth breathing is often caused by nasal obstruction: allergies, colds, chronic sinus problems, a deviated septum, nasal polyps, enlarged adenoids or tonsils, and enlarged turbinates. Effects include dry mouth, bad breath, sore throat on waking, snoring, poor sleep, more cavities and gum problems, and in growing children a narrow palate, crowded teeth and a long face. Treatment targets the cause: allergy treatment, nasal rinses and sprays, treating infections, adenoid or septum surgery when needed, myofunctional therapy and sleep evaluation. Children with persistent mouth breathing, snoring or restless sleep should be assessed.

Important. Pauses in breathing during sleep, loud snoring with daytime sleepiness, poor concentration or behaviour problems in children, a persistent blocked nose on one side with bleeding or facial pain, or breathing difficulty should be evaluated by a doctor.

What is mouth breathing?

The nose is designed for breathing: it filters, warms and humidifies the air and produces nitric oxide that helps the lungs absorb oxygen. When nasal airflow is limited, people switch to the mouth. Breathing through the mouth during intense exercise or when you have a cold is normal. It becomes a problem when it is the default at rest or during sleep for months or years.

Common causes

Nasal allergies and chronic rhinitis. See stuffy nose.
Common cold and chronic sinusitis. See sinus infection home remedies.
Deviated septum or narrow nasal passages.
Enlarged turbinates.
Nasal polyps. See nasal polyps.
Enlarged adenoids or tonsils, the main cause in children.
Habit, persisting after the original blockage is gone.
Structural jaw features such as a small lower jaw or retrognathia.
Sleep apnoea and snoring. See snoring remedies.
Pregnancy, hormonal rhinitis and overuse of decongestant sprays (rebound congestion).

Signs of mouth breathing

Mouth open at rest or during sleep, dry lips and cracked corners of the mouth.
Dry mouth, bad breath and sore throat on waking.
Snoring, restless sleep, waking unrefreshed, daytime tiredness.
Blocked nose, frequent colds, hoarse voice.
In children: dark circles under the eyes, chewing with the mouth open, drooling, speech problems, poor concentration and irritability.
More cavities, gum inflammation and dental plaque.

Effects on health

Mouth breathing dries the mouth, reducing the protective effect of saliva, which increases cavities, gum disease and bad breath. It bypasses the nose’s filter, so more dust and germs reach the throat. Sleeping with the mouth open is associated with snoring and can worsen obstructive sleep apnoea. Poor sleep affects mood, attention and growth. It can also trigger a sore throat and a feeling of dryness at night. See dry throat.

Mouth breathing in children

In children, long-term mouth breathing may influence facial and dental development: a narrow high palate, crowded or misaligned teeth, an open bite, a long face and a retruded jaw. It is also linked to snoring, sleep-disordered breathing, daytime sleepiness, hyperactivity and learning difficulties. Common causes are allergic rhinitis and enlarged adenoids. Early assessment by a paediatrician, ENT specialist and, when needed, an orthodontist helps. Treating nasal obstruction early gives the best chance of normal development.

How is the cause found?

The doctor asks about nasal symptoms, allergies, snoring and sleep, and examines the nose, mouth and throat. An ENT specialist may look inside the nose and throat with a small camera, and may order allergy tests, an X-ray of the adenoids in children, a sleep study if apnoea is suspected, or imaging of the sinuses. A dentist or orthodontist assesses bite and jaw development.

How to treat and stop mouth breathing

Treat nasal allergy: avoid triggers, saline rinses, steroid nasal sprays, antihistamines.
Treat infections and sinus problems as advised by your doctor.
Avoid overusing decongestant sprays (limit to 3 days).
Surgery when appropriate: adenoidectomy, septoplasty, turbinate reduction, polyp removal.
Myofunctional (orofacial) therapy to retrain tongue posture, lip seal and nasal breathing, often with a speech therapist.
Nasal dilator strips or cups can help some adults at night.
Orthodontic treatment in children, such as palatal expansion, when indicated.
Position and environment: sleep on your side, keep the bedroom humid and clean.

What about mouth taping?

Taping the mouth shut at night has become popular on social media, but there is little good evidence that it improves sleep or health, and it can be dangerous if the nose is blocked, in people with sleep apnoea, nasal obstruction, anxiety or in children. It is better to find and treat why you breathe through the mouth. Do not tape the mouth without medical advice.

Simple habits to encourage nasal breathing

Rinse your nose with saline before bed.
Practise relaxed nasal breathing during the day: lips closed, tongue resting on the roof of the mouth, slow diaphragmatic breaths.
Drink water and keep the air humid.
Exercise regularly to improve breathing control.
Check in with yourself during desk work, as concentration often leads to an open mouth.
Use the above together with treatment, not instead of it, if your nose is truly blocked.

When to see a doctor

A blocked nose that lasts more than 3–4 weeks or recurs often.
Snoring, pauses in breathing or daytime sleepiness.
Children with persistent mouth breathing, snoring, restless sleep or school difficulties.
One-sided blockage with bleeding, facial pain or reduced smell.
Frequent sore throats, ear infections or sinus infections.
Dental or jaw concerns noticed by your dentist.

Three common situations

A child who snores and sleeps with the mouth open: assessment for adenoids and allergies.

An adult who wakes with a dry mouth and sore throat: check for nasal blockage, allergy and sleep apnoea.

Someone who breathes through the mouth out of habit although the nose is clear: myofunctional exercises can help.

Key points to remember

Mouth breathing is a sign, not a diagnosis: find out why the nose is blocked. Treat allergy, infection, polyps or enlarged adenoids, practise nasal breathing and see a specialist for children, snoring or persistent symptoms. Our ENT team can examine your nose and airway.

This guide is for general information and does not replace an examination by your own doctor or ENT specialist.

Questions about mouth breathing

These answers are general information and do not replace an examination or individual medical advice.

Why do I breathe through my mouth?

Usually because the nose is blocked by allergies, congestion, a deviated septum, polyps or enlarged adenoids; sometimes it is just a habit.

Is mouth breathing harmful?

Long-term mouth breathing can cause dry mouth, bad breath, cavities, poor sleep and, in children, dental and facial changes.

How do I stop mouth breathing at night?

Treat the nasal obstruction, rinse your nose before bed, and ask a clinician about myofunctional therapy or dilators.

Does mouth taping work?

There is little evidence, and it can be unsafe if your nose is blocked or you have sleep apnoea.

Can mouth breathing change a child’s face?

Persistent mouth breathing during growth may contribute to a narrow palate and long face; early treatment helps.

When should I see a doctor?

If it persists, with snoring, sleep problems, frequent infections or in a child.

Sources

This guide is for general information and does not replace medical advice. How a problem is diagnosed and treated depends on your examination and medical history. If you think you have an emergency, contact your local emergency services.