Mouth breathing usually occurs when breathing comfortably through the nose is difficult, although it can also become a habitual pattern. Nasal congestion, allergies, a deviated septum, enlarged turbinates, nasal polyps, and other structural or airway problems can restrict nasal airflow.
Occasional mouth breathing during a cold or exercise is common. However, persistent symptoms, particularly during sleep, may indicate an underlying nasal or upper-airway condition that needs assessment.
In children, ongoing nasal obstruction may also affect sleep and has been associated with differences in dental and facial development.
In this guide, we’ll explain the common causes of mouth breathing, how mouth breathing can present differently in adults and children, the signs and potential problems to watch for, when to see an ENT specialist, and how the underlying cause can be diagnosed and treated.
What Is Mouth Breathing?
Mouth breathing means breathing through the mouth instead of primarily through the nose. It may occur occasionally during a cold, exercise, or temporary nasal congestion, but breathing pattern can indicate that the nasal airway is not functioning comfortably.
The nose filters, warms, and humidifies inhaled air before it reaches the lower respiratory tract. When nasal airflow is restricted, a person may naturally rely more on the mouth to breathe comfortably.
Occasional mouth breathing is not necessarily a cause for concern. However, a persistent pattern may indicate nasal obstruction, inflammation, or another upper-airway problem.
Nighttime symptoms deserve particular attention when accompanied by frequent snoring, restless sleep, pauses in breathing, or daytime tiredness.
Why Do People Breathe Through Their Mouth?
Several conditions can make nasal breathing difficult. Some cause temporary congestion, while others involve persistent inflammation or structural narrowing.
Nasal Congestion and Allergies
A blocked or stuffy nose can make it difficult to breathe comfortably through the nose, causing a person to rely more on their mouth. Nasal congestion may occur temporarily with a cold or respiratory infection, but it can also persist because of allergic rhinitis, non-allergic rhinitis, or ongoing nasal inflammation.
Allergic rhinitis is a common cause of persistent nasal congestion. It causes inflammation of the nasal lining and may lead to symptoms such as sneezing, itching, a runny nose, and difficulty breathing through the nose. When congestion continues, particularly at night, mouth breathing may become more frequent.
Temporary congestion does not necessarily indicate a long-term problem. However, if nasal blockage and mouth breathing continue after an infection has resolved, it is worth investigating whether another cause is contributing.
For more information about allergic rhinitis, see the American Academy of Allergy, Asthma & Immunology guide to allergic rhinitis.
Respiratory infections
A cold or other respiratory infection can temporarily block the nose because of swelling and mucus production. Mouth breathing during an acute infection is therefore common and does not necessarily indicate a long-term problem.
However, if mouth breathing continues after the infection has resolved, another cause should be considered.
Deviated septum
The nasal septum separates the left and right nasal passages. When it is significantly deviated, it can narrow one or both sides of the nose and contribute to chronic nasal obstruction and mouth breathing.
Not everyone with a deviated septum has symptoms. Some people have a septal deviation but breathe normally, while others may experience ongoing nasal blockage, difficulty breathing through one side of the nose, or increased reliance on mouth breathing.
Whether treatment is necessary depends on the symptoms and how much the deviation is affecting nasal airflow. Our guide to Septoplasty vs. Rhinoplasty explains the difference between procedures that address nasal function and those that address the external shape and structure of the nose.
Enlarged turbinates
Turbinates are structures inside the nose that help warm and humidify the air. When they become enlarged or swollen, they can reduce the available space for airflow through the nasal passages.
Turbinate enlargement may be associated with allergies, infections, non-allergic rhinitis, chronic inflammation, or other factors. Some people may notice nasal blockage that becomes more noticeable when lying down or sleeping, which can contribute to nighttime mouth breathing. See ENT Health’s guide to turbinate hypertrophy for more information.
Nasal valve problems
The nasal valve is one of the narrowest areas of the nasal airway. Weakness or narrowing in this region can restrict airflow, sometimes causing symptoms that are mistaken for allergies or general congestion.
Patients with nasal valve problems may notice difficulty breathing through the nose during exercise, while sleeping, or during everyday activities. Some may also notice that gently widening the sides of the nose makes breathing easier.
Read our detailed guide: What Is Nasal Valve Collapse and Can Rhinoplasty Fix It?
Nasal Polyps and Sinus Disease
Nasal polyps are soft, non-cancerous growths that develop from inflamed tissue inside the nose or sinuses. When polyps become large or occur in multiple areas, they can obstruct the nasal passages and make nasal breathing difficult.
Chronic sinus inflammation can also contribute to ongoing nasal congestion and reduced airflow. In these situations, a person may gradually rely more on mouth breathing because breathing through the nose feels difficult or uncomfortable.
Enlarged adenoids or tonsils
In children, enlarged adenoids and tonsils can narrow the upper airway and make nasal breathing more difficult. Children with enlarged adenoids or tonsils may breathe through their mouths, snore, have noisy breathing, or sleep restlessly. When mouth breathing occurs together with frequent snoring, restless sleep, or other signs of disturbed breathing, an ENT evaluation may be appropriate.
Sleep-Related Breathing Problems
Mouth breathing can become particularly noticeable during sleep. A person may sleep with their mouth open because nasal airflow is restricted, or because other factors are affecting breathing during sleep.
Nighttime mouth breathing may occur alongside snoring, restless sleep, noisy breathing, or sleep-disordered breathing. In children, parents may also notice pauses in breathing, gasping, frequent waking, or unusual sleeping positions.
Mouth breathing alone does not mean that someone has sleep apnea. However, persistent mouth breathing combined with significant snoring or pauses in breathing should be evaluated rather than assumed to be a simple habit.
Habitual mouth breathing
Sometimes mouth breathing continues even after the original nasal obstruction has improved. A person may have become accustomed to breathing through the mouth, particularly if nasal obstruction was present for a prolonged period.
This does not mean that every habitual mouth breather has a structural problem. The important step is to determine whether nasal airflow is currently adequate and whether another nasal or upper-airway condition is contributing.
This is why persistent mouth breathing should be assessed in context rather than treated as a habit alone.
Mouth Breathing in Adults
In adults, persistent symptoms are often associated with chronic nasal obstruction. Allergies, a deviated septum, enlarged turbinates, nasal polyps, nasal valve narrowing, and changes following nasal injury or surgery can all contribute.
Dr. Hatem Dalati, ENT Consultant & Rhinoplasty Surgeon, approaches persistent mouth breathing by first identifying the underlying cause of nasal or upper-airway obstruction. This means assessing more than the septum alone, as the nasal valves, turbinates, nasal lining, and overall nasal structure can also influence airflow.
Common causes in adults include:
- Chronic nasal blockage – Persistent congestion can make nasal breathing difficult.
- Allergies – Allergic inflammation can swell the nasal lining and turbinates.
- Deviated septum – A significantly deviated septum may narrow one or both nasal passages.
- Nasal valve narrowing or collapse – Structural narrowing or weakness can restrict airflow.
- Turbinate enlargement – Enlarged turbinates can reduce the available space inside the nasal airway.
- Nasal polyps – Larger or multiple polyps can obstruct the nasal passages.
- Previous nasal injury or surgery – Trauma or previous surgery can alter the nasal framework and affect airflow.
- Snoring and sleep-related breathing problems – Nasal obstruction can contribute to nighttime mouth breathing, snoring, and disturbed sleep.
Several causes may occur together. For example, a deviated septum may coexist with turbinate enlargement or nasal valve narrowing. Identifying all relevant factors helps guide treatment.
Mouth Breathing in Children
Persistent symptoms in children deserve particular attention because nasal obstruction can interfere with sleep and daytime functioning. Common causes include enlarged adenoids or tonsils, allergic rhinitis, chronic congestion, and other forms of nasal obstruction.
Parents may notice that their child:
- Frequently sleeps with their mouth open
- Snores regularly
- Has restless or disturbed sleep
- Wakes with a dry mouth
- Has persistent nasal congestion
- Appears tired or less rested during the day
Frequent snoring, gasping, pauses in breathing, or unusual breathing patterns during sleep should not be dismissed as normal childhood habits. An ENT specialist can assess whether enlarged adenoids, tonsils, or another condition is contributing.
Possible Effects on Children’s Dental and Facial Development
In children, prolonged mouth breathing has been associated with certain dental and craniofacial patterns, including changes in dental arch shape, bite, and facial growth.
However, these changes should not be presented as an inevitable result of mouth breathing. Facial and dental development is influenced by many factors, and much of the available research shows an association rather than clear proof that mouth breathing alone causes these changes.
For this reason, persistent mouth breathing in a child should be assessed in the context of other findings, such as nasal obstruction, enlarged adenoids or tonsils, allergies, snoring, and sleep quality.
Does Mouth Breathing Change a Child’s Face?
This is an area where it is important to be precise.
Research has found associations between persistent mouth breathing and differences in facial and dental development in children, including changes in dental arches, jaw relationships, and facial growth patterns. A systematic review and meta-analysis published in BMC Oral Health and indexed in PubMed found differences in several measures of facial skeletal development and malocclusion between mouth-breathing and nasal-breathing children.
However, mouth breathing does not mean every child will develop facial or dental changes. A more recent 2026 systematic narrative review also reported an association while noting that the available evidence does not establish a definitive cause-and-effect relationship.
For this reason, persistent mouth breathing in a child should prompt an evaluation of why nasal breathing is difficult, rather than assuming that mouth breathing itself is the sole cause of developmental changes.
Adenotonsillectomy with Dr. Hatem Dalati in Dubai
Adenotonsillectomy is performed when enlarged tonsils and adenoids cause significant symptoms and surgery is considered appropriate. Each child’s treatment and recovery are individual.
These patients underwent adenotonsillectomy with Dr. Hatem Dalati at ENT Clinic of Excellence, Dubai Healthcare City.
What Are the Common Signs and Symptoms?
Symptoms vary depending on the person’s age and the underlying cause.
| Adults | Children |
|---|---|
| Chronic nasal blockage | Frequent nasal congestion |
| Dry mouth on waking | Open-mouth sleeping |
| Dry or irritated throat | Dry mouth or lips |
| Snoring | Frequent snoring |
| Difficulty breathing through the nose | Noisy or restless sleep |
| Nasal breathing that worsens at night | Pauses or gasping during sleep |
| History of allergies or nasal surgery | Daytime tiredness or attention changes |
Not everyone experiences all these symptoms. Their presence should be considered alongside the person’s medical history and other findings.
Can Mouth Breathing Cause Problems?
Occasional mouth breathing during a cold is different from a persistent pattern associated with chronic nasal obstruction.
Long-term mouth breathing can contribute to:
Dry Mouth and Throat Irritation
Regularly breathing through the mouth can increase moisture loss from the oral tissues, leading to dryness, throat irritation, and discomfort upon waking.
Persistent dry mouth may also contribute to bad breath and oral health problems because saliva helps protect the teeth and maintain a healthy oral environment. The American Dental Association’s guide to dry mouth explains its potential effects.
Snoring and Disturbed Sleep
Nasal obstruction can contribute to snoring and disturbed sleep. In some people, particularly children, persistent snoring and mouth breathing may be signs of sleep-disordered breathing that deserves medical assessment.
Daytime Symptoms
Poor-quality sleep associated with chronic nasal obstruction or sleep-disordered breathing may contribute to daytime tiredness, difficulty concentrating, or reduced alertness.
In children, disturbed sleep may sometimes appear as changes in behavior, attention, or school performance rather than obvious daytime sleepiness.
Importantly, these symptoms are not caused by mouth breathing alone in every case. They may reflect the underlying nasal or airway problem affecting sleep.
Oral Health Problems
Persistent mouth breathing can reduce moisture in the mouth. A dry oral environment may contribute to problems such as bad breath, increased plaque accumulation, tooth decay, and gum irritation, particularly when other risk factors are present.
Maintaining good oral hygiene and addressing the reason for chronic mouth breathing are therefore both important.
How Is the Cause Diagnosed?
When evaluating persistent mouth breathing, Dr. Hatem Dalati, ENT Consultant & Rhinoplasty Surgeon, takes an ENT-focused approach to understanding why nasal breathing is difficult.
The assessment may include a detailed medical history and examination of the nose and upper airway, including the septum, turbinates, nasal valves, nasal lining, tonsils, and adenoids when appropriate.
Medical History
Dr. Dalati may ask about:
- How long you have been mouth breathing
- Whether symptoms are worse during sleep
- Snoring or sleep disturbances
- Allergies
- Previous nasal injuries
- Previous nasal surgery
- Recurrent infections
- Difficulty breathing through one or both nostrils
- Changes in smell
Nasal and Upper-Airway Examination
The nose can be assessed for:
- Septal deviation
- Turbinate enlargement
- Nasal valve narrowing or collapse
- Nasal polyps
- Inflammation
- Structural abnormalities
In children, the examination may also include the tonsils and adenoids. In selected cases, nasal endoscopy or other investigations may be recommended.
Because more than one condition can contribute to obstruction, identifying the relevant factors helps determine the most appropriate treatment.
Patient Testimonial: Functional Rhinoplasty with Dr. Hatem Dalati
In this testimonial, our patient shares their experience with functional rhinoplasty and their breathing concerns before surgery.
Watch this Reel on Instagram
How Is Mouth Breathing Treated?
Treatment depends on the underlying cause. Simply trying to keep the mouth closed may not address the problem if nasal airflow is restricted.
Allergies or nasal inflammation
If allergic rhinitis is contributing to nasal obstruction, treatment may focus on controlling the underlying inflammation and allergy triggers. Depending on the diagnosis, an ENT or allergy specialist may recommend appropriate medical treatment.
Deviated septum
If a significantly deviated septum is responsible for persistent nasal obstruction and symptoms do not respond adequately to medical management, septoplasty may be considered.
You can read more in our article Septoplasty vs Rhinoplasty: What’s the Difference?.
Enlarged turbinates
Treatment for enlarged turbinates depends on their cause and severity. Medical treatment may be appropriate in some patients, while selected patients with persistent structural obstruction may be considered for turbinate reduction.
Nasal valve problems
When nasal valve narrowing or collapse contributes significantly to obstruction, treatment may require structural support of the nasal airway. In selected patients, functional rhinoplasty or nasal valve repair may be considered.
Enlarged tonsils or adenoids
If enlarged tonsils or adenoids are contributing to significant sleep-disordered breathing or airway obstruction, an ENT specialist can determine whether medical management, observation, or surgery is appropriate. Not every child who snores requires surgery.
Structural nasal problems after injury or previous surgery
Some adults develop persistent obstruction after nasal trauma or previous nasal surgery. In these situations, treatment may require a detailed assessment of the nasal framework, septum, and nasal valves.
If both breathing and external nasal structure are affected, septorhinoplasty may sometimes be considered. Learn more in our guide What Is Septorhinoplasty and How Does It Improve Your Nose and Breathing?
Habitual mouth breathing
If no significant obstruction remains but mouth breathing has become habitual, the approach may be different. The underlying nasal airway should first be assessed before assuming that the problem is simply a habit.
When Should You See an ENT?
Consider an ENT assessment if mouth breathing is persistent, affects sleep, or makes nasal breathing difficult.
Seek medical advice if you experience:
- Chronic nasal blockage or difficulty breathing through the nose
- Frequent snoring or restless sleep
- Pauses in breathing or gasping during sleep
- Recurrent nasal or sinus symptoms
- Mouth breathing following nasal injury or surgery
In children, regular open-mouth sleeping, frequent snoring, or disturbed sleep should be evaluated, particularly when breathing pauses or gasping occur.
An ENT specialist can identify underlying causes, such as allergies, a deviated septum, enlarged turbinates, nasal valve problems, or enlarged tonsils and adenoids.
Frequently Asked Questions
Is mouth breathing normal?
Occasional mouth breathing can happen during a cold, exercise, or temporary nasal congestion. Persistent mouth breathing, especially during sleep, may indicate nasal or upper-airway obstruction and deserves evaluation.
Why do I breathe through my mouth when I sleep?
Nighttime symptoms can occur when allergies, congestion, a deviated septum, enlarged turbinates, or nasal valve problems restrict airflow. Frequent snoring or pauses in breathing should also be assessed.
Why does my child sleep with their mouth open?
Possible causes include enlarged adenoids or tonsils, allergic rhinitis, and chronic nasal congestion. If the pattern is frequent or accompanied by snoring and restless sleep, an ENT evaluation may help identify the cause.
Is mouth breathing a sign of a deviated septum?
It can be, but a deviated septum is only one possible cause. Allergies, enlarged turbinates, nasal valve problems, polyps, and other conditions can also restrict nasal airflow.
Can allergies cause mouth breathing?
Yes. Allergic rhinitis can cause persistent nasal inflammation and congestion, making nasal breathing more difficult and potentially encouraging mouth breathing.
Can mouth breathing affect a child’s facial development?
Persistent mouth breathing has been associated with differences in facial and dental development in children. However, it does not mean every child will develop these changes, and multiple factors can influence facial growth.
Can rhinoplasty improve breathing?
In selected patients, functional rhinoplasty can address structural problems affecting nasal airflow, including certain nasal valve or external nasal framework problems. Rhinoplasty is not automatically a breathing treatment; the appropriate procedure depends on the underlying anatomy.
The Bottom Line: Find the Cause, Not Just the Symptom
Persistent mouth breathing may be related to allergies, nasal congestion, a deviated septum, enlarged turbinates, nasal valve problems, nasal polyps, or enlarged adenoids and tonsils.
In children, ongoing symptoms deserve attention, particularly when accompanied by snoring or disturbed sleep. In adults, chronic nasal obstruction or breathing difficulties following nasal injury or surgery may warrant a detailed assessment.
The goal is not simply to stop breathing through the mouth. It is to understand why comfortable nasal breathing is difficult and address the underlying cause.
Book an ENT Consultation in Dubai
If you or your child regularly breathes through the mouth, especially during sleep, an ENT assessment can help identify whether nasal obstruction, allergies, enlarged tissues, or a structural problem is contributing.
At ENT Clinic of Excellence, Dr. Hatem Dalati is an ENT Consultant & Rhinoplasty Surgeon with a focus on both nasal function and structural anatomy. His ENT approach considers the nasal airway as well as the external nose when evaluating patients with breathing concerns.
ENT Clinic of Excellence – Dubai Healthcare City
📍 Location: Building 64 – Block A, 2nd Floor – Unit 2004, Umm Hurair 2, Dubai Healthcare City, Dubai
📱 Call / WhatsApp: 050 248 0249
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If nasal breathing is difficult, the first step is finding out why.