How should I evaluate and manage a 5‑year‑old with persistent mouth breathing that worsens in winter?

Evaluation and Management of Persistent Mouth Breathing in a 5-Year-Old

A 5-year-old with constant mouth breathing that worsens in winter most likely has adenoidal hypertrophy with or without allergic rhinitis, and should be evaluated by an otolaryngologist for nasal endoscopy to assess adenoid size and rule out other anatomical obstructions. 1

Initial Clinical Assessment

The evaluation should focus on identifying the specific cause of upper airway obstruction:

• Assess for adenoidal hypertrophy, which is the most common acquired cause of nasal obstruction and mouth breathing in children, typically presenting with nasal speech, snoring, and sleeping with mouth open 1, 2
• Look for signs of allergic rhinitis (81.4% of mouth breathers), including itchy nose, nasal congestion that fluctuates with seasons, and clear rhinorrhea 2
• Document sleep-related symptoms: snoring (79% of mouth breathers), sleeping with mouth open (86%), drooling on pillow (62%), and agitated sleep 2
• Examine for facial and dental changes: long narrow face, high palatal vault, dental malocclusion, incompetent lips, or anterior open bite that develop from chronic mouth breathing 3, 4

The seasonal worsening in winter strongly suggests an allergic or inflammatory component superimposed on anatomical obstruction 2.

Diagnostic Workup

Nasal endoscopy by an otolaryngologist is the key diagnostic test to directly visualize:

• Adenoid size and degree of nasopharyngeal obstruction (79.2% of mouth breathers have enlarged adenoids) 2
• Inferior turbinate hypertrophy (55% of mouth breathers) 5, 2
• Nasal septal deviation (55% of mouth breathers) 5, 2
• Concurrent sinusitis (77% have maxillary sinusitis, 45% ethmoidal sinusitis) 5

Additional testing to consider:

• Allergy skin testing if allergic rhinitis is suspected based on seasonal variation and nasal symptoms 2
• Lateral neck radiograph can assess adenoid size if endoscopy is not immediately available, though direct visualization is superior 2

Important caveat: Approximately 13% of mouth-breathing children do not have adenoid hypertrophy, and 9.6% have completely normal anatomy, representing habitual non-obstructive mouth breathing 5. However, given the constant nature and winter worsening, anatomical obstruction is most likely.

Management Algorithm

For adenoidal hypertrophy with obstructive symptoms:

• Adenoidectomy is indicated when adenoidal hypertrophy causes persistent mouth breathing, as this is the primary indication for the procedure 1
• Surgery should not be delayed, as chronic mouth breathing causes progressive craniofacial changes that become increasingly difficult to reverse with age 3, 4

For concurrent allergic rhinitis:

• Initiate intranasal corticosteroids to reduce turbinate hypertrophy and nasal inflammation 2
• Consider oral antihistamines for symptomatic relief during allergy seasons 2

If mouth breathing persists after adenoidectomy:

• Reassess for other mechanical obstacles including deviated septum, turbinate hypertrophy, or chronic sinusitis that may require additional intervention 5
• Consider myofunctional therapy for habitual mouth breathing if no residual anatomical obstruction is found 6

Critical Pitfalls to Avoid

• Do not dismiss this as a benign habit. Untreated mouth breathing causes long-term craniofacial deformities, sleep disruption affecting growth and academic performance, and increased risk of dental caries and periodontal disease 3, 4
• Do not empirically treat as asthma without proper evaluation, as mouth breathing is not a lower airway problem 7
• Do not delay referral to ENT waiting for the child to "grow out of it"—early intervention prevents irreversible facial and dental changes 3, 4
• Screen for obstructive sleep apnea, as mouth breathing is a cardinal symptom and these children may have significant nocturnal hypoxemia not detected by daytime assessment 1, 6