How Mouth Breathing Changes a Child's Face: Long Face, Receding Jaw and Other Facial Development Problems

Short answer: Long-term mouth breathing in childhood changes how the face grows: a longer, narrower face, a receding chin, flatter cheeks, a narrow nose, a gummy smile and lips that don't close at rest.

Medically reviewed by Dr. Prashanth R. Reddy, ENT Surgeon (MS ENT) · Last reviewed: 31 October 2026

What is 'adenoid face'?

It's the term doctors use for facial features seen in children who breathe through the mouth for years: a long, narrow face, a receding chin, an open mouth with lips that don't close at rest, a narrow upper jaw and often dark circles under the eyes.

How mouth breathing changes the face

To breathe through the mouth, a child keeps the jaw slightly open and the tongue low. During growth, the lower jaw rotates downward and backward, so the lower face lengthens and the chin appears to recede. Classic studies linked enlarged adenoids and mouth breathing with these facial patterns (Linder-Aronson, 1970), and a 2021 systematic review confirmed a more backward-placed jaw and longer face in mouth-breathing children (Zhao et al.).

Other facial development changes in children

• Long, narrow face: the lower third of the face grows longer.
• Receding chin and lower jaw that sits further back.
• Flat cheeks and an under-developed midface, because the upper jaw grows narrow and set back.
• Narrow nose and nostrils, since the roof of the mouth is also the floor of the nose.
• High-arched palate and crowded teeth, often with a crossbite or open bite.
• Gummy smile and protruding upper teeth, with a short, slack upper lip.
• Lips that don't close at rest and a weak lip seal.
• Dark circles under the eyes ('allergic shiners') and a tired look from poor sleep.
• Forward head posture, as the head tilts forward to open the airway.

Why timing matters

Facial bones respond to breathing while a child is growing. Treating the cause early gives the face the best chance to grow normally. In adults the bones are set, but improving nasal breathing still helps sleep, snoring and dental health.

Why do people breathe through the mouth?

Usually because the nose doesn't let enough air through. Common reasons are a deviated septum, swollen turbinates, nasal allergy, chronic sinusitis, nasal polyps and, in children, enlarged adenoids and tonsils. Sometimes it starts as a habit and stays even after the nose clears.

Signs you or your child may be a mouth breather

• Lips apart at rest or during sleep
• Snoring, dry mouth or drooling on the pillow
• Waking tired, dark circles under the eyes
• Bad breath and frequent throat clearing
• Always 'blocked' nose, especially at night

What helps

1. Find out why the nose is blocked. An ENT evaluation (examination plus a CT scan of the nose where needed) shows whether it's the septum, turbinates, allergy, sinuses or adenoids.
2. Treat the cause, from allergy control and nasal sprays to correcting a blockage when it's needed.
3. Work with your dentist or orthodontist on the teeth, gums and bite.
4. Re-train nasal breathing once the nose is open, with lips closed at rest.

When to see an ENT

If you or your child breathe through the mouth most of the time, snore, or have a constantly blocked nose, an ENT evaluation can find the cause.

References

• Zhao Z, et al. Effects of mouth breathing on facial skeletal development in children: a systematic review and meta-analysis. BMC Oral Health. 2021;21:108.
• Linder-Aronson S. Adenoids: their effect on mode of breathing and nasal airflow and their relationship to characteristics of the facial skeleton and the dentition. Acta Oto-Laryngologica Supplementum. 1970;265:1-132.
• Harvold EP, et al. Primate experiments on oral respiration. American Journal of Orthodontics. 1981;79(4):359-372.

Related reading: Mouth breathing and bad breath · Mouth breathing and tooth decay · Mouth breathing and gum disease · Mouth breathing and crooked teeth · Mouth breathing and a high-arched palate

About the author

Dr. Prashanth R. Reddy is a Senior Consultant ENT Surgeon in Bengaluru (MS ENT; Fellowship in Rhinoplasty, Seoul; MBA, IIM Bangalore) with over two decades of practice. He sees patients at Sakra World Hospital, Marathahalli and at the ENTHealth360 clinic in Koramangala.

For educational purposes only. Not a substitute for medical advice. Please consult a qualified ENT specialist.