Mouth breathing in children: what parents should know

Many children breathe through their mouth for a while — with a cold, hay fever or a blocked nose. If your child breathes through their mouth most of the time, including at night, it's worth a check with your GP, and worth mentioning at their next dental visit.¹

This article explains common causes, what the research says, and where a dentist fits in. To see how we look at breathing and habits during children's check-ups, read about airway-focused dentistry.

Common reasons children breathe through their mouth

• A blocked nose from colds or allergies.
• Enlarged adenoids or tonsils. Adenoids sit at the back of the nose and are largest around ages 3 to 5. They usually shrink from about 5 to 8, and are mostly gone by the teenage years.¹ When they're enlarged, they can block nose breathing, so children breathe through their mouth instead.¹
• Habit. Sometimes mouth breathing continues after the original cause has gone.

When to see your GP

Talk to your GP if your child:

• breathes through their mouth most of the time
• snores most nights
• seems to pause, gasp or struggle to breathe while asleep

Enlarged adenoids can contribute to obstructive sleep apnoea — short pauses in breathing during sleep — and significant, untreated sleep apnoea may affect a child's growth and development.¹ A doctor diagnoses this, sometimes with a sleep study, and may refer to an ear, nose and throat (ENT) specialist.¹ Most adenoid problems settle as children grow.¹

What the research says about teeth and jaws

Studies have found that children who mainly breathe through their mouth tend, on average, to show differences in how their jaws grow and how their teeth meet — for example, the jaws angled further back and down, and the upper front teeth tipped forward.²

It's important to read this carefully:

• These studies show a link, not that mouth breathing causes these changes.
• The studies looked back at children after the fact, and the overall quality of evidence is limited.²
• Every child is different. Mouth breathing doesn't mean a problem is certain.

Where a dentist fits in

Dentists see children regularly, so we're often in a good position to notice signs early. At a check-up, a dentist can look at:

• how the top and bottom teeth meet, and the width of the upper jaw
• the position of the tongue and lips at rest
• habits like thumb or dummy sucking, which can affect the teeth and bite if they continue as adult teeth come through³

What a dentist can't do is diagnose sleep apnoea or other medical conditions — that's a job for your doctor.¹ A good next step is often simply monitoring, or a referral: to your GP, an ENT specialist, a speech pathologist or myofunctional therapist, or a specialist orthodontist.

In short

• Occasional mouth breathing with a cold is normal.
• Mouth breathing most of the time, or snoring most nights, deserves a GP check.
• Research links mouth breathing with differences in jaw growth, but the evidence is limited.
• Dentists can help notice the signs and point you to the right professional.

Want us to take a look? Book a check-up for your child, or read more about airway-focused dentistry and early orthodontic assessment.