Mouth Breathing in Children: When It's More Than a Phase

Q: Is mouth breathing harmful for children?

Chronic mouth breathing — meaning habitual breathing through the mouth at rest, not just during exercise or with a cold — is not benign. Over time it affects the development of the palate, dental alignment, facial structure, sleep quality, and in some cases speech. It is not something to wait out.

Q: How is mouth breathing treated with myofunctional therapy?

Myofunctional therapy for mouth breathing focuses on retraining nasal breathing as the default, improving tongue resting posture, strengthening lip seal tone, and addressing the swallowing patterns that often accompany the mouth-breathing habit. If a structural cause (enlarged adenoids, deviated septum) is present, an ENT referral may be needed in parallel. The two approaches are complementary.

Lots of children breathe through their mouths sometimes. During a cold, after running around the yard, when allergies are acting up. That is normal and not worth worrying about.

But there is another kind of mouth breathing. The child who always sleeps with their mouth open. Who always looks like their lips are slightly parted. Whose teeth have never quite lined up the way the dentist expected. Who snores. Who seems tired even after a full night of sleep. Who was referred by the orthodontist for something and the parent is not quite sure why.

That kind of mouth breathing is not a phase. It is a pattern — and one that accumulates consequences over years of a child's development if it is not addressed. As a myofunctional therapy specialist in Sandy Springs, I see the downstream effects of this pattern regularly. This post explains what those effects are, what causes them, and when to act.

What Normal Breathing Looks Like

At rest, normal breathing happens through the nose. The lips are closed. The tongue is gently in contact with the roof of the mouth, just behind the front teeth. The jaw is slightly relaxed but the lip seal is maintained.

This is not a minor anatomical detail. Nasal breathing filters, humidifies, and warms incoming air. The nose produces nitric oxide, which dilates the airways and improves oxygen uptake. Nasal breathing activates the lower lungs more fully than mouth breathing and supports the diaphragm's natural role in breathing mechanics.

When a child breathes through their mouth habitually, none of that happens. And the consequences extend well beyond air quality.

What Chronic Mouth Breathing Does to a Developing Child

Children's facial structures are still forming. The palate, jaw, and airway shape are actively developing throughout childhood and into early adolescence. The forces applied during that window — including the position of the tongue and lips at rest — matter enormously for how those structures develop.

Dental Development

The tongue resting on the floor of the mouth instead of the palate removes the natural pressure that shapes palatal width. The result is a narrower arch, more crowding of permanent teeth, and a higher likelihood of needing orthodontic intervention.

Facial Growth

Chronic mouth breathing is associated with a longer, narrower facial structure — a pattern sometimes called "adenoid face." The lower jaw grows downward rather than forward, which can affect profile and bite development.

Sleep Quality

Mouth breathing during sleep is associated with snoring, increased arousal events, and less restorative sleep. Children who are chronically tired, difficult to wake, or show attention and behavioral difficulties sometimes have a sleep-disordered breathing component.

Speech and Articulation

Tongue posture directly affects how speech sounds are produced. A tongue that rests low rather than against the palate can contribute to lisping, imprecise articulation, and reduced intelligibility in some children.

At rest, breathing should happen through the nose, with lips closed and tongue gently touching the roof of the mouth. If your child does not look like this at rest, that pattern is worth evaluating.

What Causes Mouth Breathing

Mouth breathing in children is usually caused by a structural issue, a learned habit, or both:

Structural causes

Enlarged adenoids or tonsils. The most common structural cause in children. When the adenoids or tonsils are enlarged, nasal airflow is restricted and the child breathes through the mouth as a compensatory mechanism. An ENT evaluation can determine whether this is a factor.
Nasal congestion from allergies. Seasonal or environmental allergies cause chronic nasal congestion, making nasal breathing uncomfortable. Even after the allergen is controlled, the mouth-breathing habit may persist.
Deviated septum. Less common in young children but worth considering if nasal airflow is consistently restricted on one side.

Habitual patterns

A child who breathed through their mouth during a prolonged illness may continue the pattern even after the illness resolves.
Children whose muscle tone is low, whose lips do not close easily at rest, or whose tongue rests in a low position often breathe through their mouths not because the airway is blocked but because the muscles are not trained to maintain a closed lip seal.

When both factors are present, addressing only one produces partial results. If the adenoids are enlarged, removing them opens the airway but does not retrain the mouth-breathing habit that has become automatic. Myofunctional therapy addresses the habit component. The ENT addresses the structural component. For many children, both are needed.

Child during an oral assessment — evaluating tongue posture and airway function is the first step in addressing mouth breathing

Signs Your Child May Be a Habitual Mouth Breather

You do not need a test to identify this. Watch your child at rest. Look specifically when they are watching television, doing homework, or falling asleep. Ask yourself:

Are their lips parted at rest consistently?
Does their mouth fall open when they are not talking or eating?
Do they snore or breathe audibly through their mouth during sleep?
Do they seem tired in the mornings even after a full night of sleep?
Has the orthodontist or dentist mentioned a narrow palate, crowded teeth, or referred them for myofunctional therapy?
Do they have chronic dark circles under the eyes or a slightly swollen appearance around the nose and mouth?

If the answer to several of these is yes, an evaluation is worth having. It takes less than an hour and gives you a clear picture of what is present and what, if anything, needs to be addressed.

What Myofunctional Therapy Does for Mouth Breathing

Myofunctional therapy for mouth breathing focuses on four interconnected targets:

Nasal breathing retraining. Building the habit and capacity for nasal breathing at rest and during light activity through specific breathing exercises and nasal hygiene routines.
Tongue posture correction. Teaching and reinforcing the correct tongue rest position — gently on the roof of the mouth, behind the front teeth. When the tongue is in the right position, it naturally supports lip closure and nasal breathing.
Lip seal strengthening. Exercises that build lip tone and make closed-mouth rest the natural, comfortable default rather than the effortful exception.
Swallowing pattern retraining. Mouth breathing and tongue thrust often coexist. The swallowing pattern is addressed alongside the breathing work.

Sessions are structured but age-appropriate. For children ages 6 to 10, exercises are integrated into play-based activities. Older children and adolescents can follow a more straightforward exercise program. Home exercises are brief but need to be done daily — the consistency is what builds the new automatic patterns.

Myofunctional therapist guiding a child through oral muscle exercises designed to retrain nasal breathing patterns

Mouth breathing is not a character trait or a bad habit your child needs to try harder to change. It is a muscle and airway pattern. With the right evaluation and the right program, it can be addressed. The earlier the intervention, the more of your child's developmental window is still open.

Frequently Asked Questions

Is mouth breathing harmful for children?

Chronic mouth breathing is not benign. It affects palate development, dental alignment, facial growth, sleep quality, and in some cases speech. It is not something to wait out if it is a consistent pattern rather than a temporary response to illness or activity.

Can mouth breathing cause dental problems?

Yes. Mouth breathing is associated with a narrower palate, increased crowding of permanent teeth, and altered bite patterns. When the tongue rests on the floor of the mouth instead of the palate, it removes the natural force that shapes palatal width during development.

At what age should mouth breathing in a child be addressed?

There is no minimum age for evaluation. A myofunctional evaluation can identify whether mouth breathing is habitual or structural at any age. Earlier intervention during the developmental window produces better results. If your child is consistently breathing through their mouth at rest and during sleep, an evaluation is appropriate regardless of age.

Is mouth breathing related to sleep apnea in children?

Mouth breathing and pediatric sleep-disordered breathing often overlap. Enlarged tonsils or adenoids are a common cause of both. Children who snore, seem tired despite adequate sleep, or show attention difficulties may benefit from evaluation by both an ENT and a myofunctional therapist. The two approaches complement each other.

How is mouth breathing treated with myofunctional therapy?

Therapy focuses on retraining nasal breathing as the default, improving tongue resting posture, strengthening lip seal tone, and addressing swallowing patterns. If a structural cause is present, an ENT referral may be needed in parallel. The two approaches are complementary.

Wondering If Your Child's Mouth Breathing Is a Problem?

Amanda Smith, M.Ed., CCC-SLP is a speech-language pathologist specializing in myofunctional therapy in Sandy Springs, GA. A free intake consult is the fastest way to understand what is present and whether intervention makes sense.

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