Mouth Breathing in Children: Causes, Signs and When to Seek Help

Does your child sleep with their mouth open?

Perhaps you've noticed them mouth-breathing at night, snoring, grinding their teeth, or waking with a dry mouth. Maybe their lips are often apart during the day too.

It can be easy to think, “It's just a habit. They'll grow out of it.”

But persistent mouth breathing in children can sometimes be a clue that something is making nasal breathing difficult, or that the tongue, lips and oral muscles aren't functioning as effectively as they could.

The important question isn't simply “How do I stop my child mouth breathing?”

It's “Why is my child mouth breathing in the first place?”

Why does my child breathe through their mouth?

There isn't one single cause. Possible contributors include:

• Nasal congestion or allergies

• Enlarged adenoids or tonsils

• Enlarged or inflamed nasal turbinates

• Structural narrowing within the nose

• A deviated nasal septum

• Habitual open-mouth posture

• Difficulty maintaining a comfortable lip seal

• Low tongue resting posture

• Altered oral muscle function

  
  

Sometimes more than one factor is involved.

That's why simply telling a child to “close your mouth and breathe through your nose” doesn't necessarily address the underlying problem.

Signs of mouth breathing in children

Mouth breathing isn't always obvious. Parents may notice:

• Sleeping with the mouth open

• Snoring or noisy breathing

• Lips frequently apart during the day

• Dry mouth or lips in the morning

• Teeth grinding during sleep

• Restless or disrupted sleep

• Persistent nasal congestion

• Low tongue resting posture

• Difficulty comfortably keeping the lips together

• Unusual swallowing patterns

  
  

One sign alone doesn't necessarily mean there is a problem. But when several signs occur together, it's worth looking more closely.

Is it normal for a child to sleep with their mouth open?

Occasionally, yes. A cold or blocked nose may temporarily cause your child to breathe through their mouth.

Regular mouth-open sleeping is different.

If your child sleeps with their mouth open most nights, particularly alongside snoring, noisy breathing, restless sleep or persistent congestion, it's worth understanding whether something is making nasal breathing more difficult.

It doesn't automatically mean your child has an airway problem. It simply means it's worth asking why.

Can enlarged tonsils and adenoids cause mouth breathing?

They can contribute in some children.

Enlarged tonsils or adenoids, nasal inflammation and other structural factors may affect breathing.

This is where an ENT assessment can be valuable. An ENT specialist can assess the nose, tonsils, adenoids and other potential structural causes.

From a dental and myofunctional perspective, I look at the oral side of the picture, including tongue function, oral posture, swallowing, jaw and dental development.

Sometimes the best approach is multidisciplinary.

Can mouth breathing affect children's teeth and jaws?

Breathing, tongue posture, lip posture, swallowing and facial growth are closely interconnected during childhood.

As a dentist, I may look for:

• Narrow dental arches

• Dental crowding

• Open-mouth posture

• Difficulty maintaining a relaxed lip seal

• Low tongue posture

• Altered swallowing patterns

• Jaw and bite development

This doesn't mean mouth breathing alone causes crooked teeth or a particular facial shape. Genetics and many other factors influence growth.

However, oral posture and function are important pieces of the puzzle when assessing a child's dental development.

What does the tongue have to do with mouth breathing?

More than many parents realise.

I assess whether the tongue can move freely, lift appropriately, rest comfortably and coordinate effectively during swallowing.

I will also assess for a tongue restriction or tongue-tie. Importantly, finding a tongue-tie does not automatically mean your child needs a tongue-tie release.

Function matters, not simply appearance.

My child mouth breathes and snores. Should I be concerned?

Not every child who snores has a sleep disorder. However, regular snoring in children is worth discussing with a healthcare professional, particularly when accompanied by mouth breathing or disturbed sleep.

Mention symptoms such as pauses in breathing, gasping, very restless sleep, unusual sleeping positions, difficulty waking or daytime tiredness.

Depending on your child's symptoms, a medical, ENT or sleep assessment may be appropriate.

Can you stop a child from mouth breathing?

The first step isn't repeatedly telling them to close their mouth.

We need to understand whether your child can comfortably breathe through their nose.

If there is an obstruction or restriction, that needs appropriate investigation first.

Once structural concerns have been addressed or excluded, some children may benefit from support with breathing patterns, tongue posture, lip seal, swallowing and oral muscle function. This is where orofacial myofunctional therapy may have a role when appropriate.

When should I get my child's mouth breathing checked?

Consider seeking advice if your child regularly mouth breathes, sleeps with their mouth open, snores, has persistent congestion, grinds their teeth alongside other sleep symptoms, struggles to keep their lips comfortably together or has concerns around tongue movement or swallowing.

You don't need to diagnose the cause yourself.

Your job as a parent is to notice the signs. Our job as healthcare professionals is to help understand what they mean.

Looking beyond the mouth breathing

During my Airway & Myofunctional Assessment, I bring together findings from your child's breathing, sleep, tongue function, swallowing, teeth and bite, jaw and TMJ, muscles, posture and facial development.

The aim is to understand the bigger picture and give you a clearer roadmap for what happens next.

You'll receive a detailed written report and personalised next steps, including onward referral where appropriate.

See the whole picture. Understand what matters. Know what to do next.

Concerned about your child’s mouth breathing?

→ Learn more about my comprehensive airway & myofunctional assessment or book an assessment.

I look forward to helping you understand the bigger picture.

Dr JJ