What are the differential diagnoses and recommended management for cough in children?

Differential Diagnoses for Pediatric Cough

The differential diagnosis of cough in children depends critically on duration (acute <4 weeks versus chronic ≥4 weeks), cough quality (wet/productive versus dry), and the presence of specific cough pointers that suggest serious underlying disease. 1

Classification by Duration

Acute Cough (<4 Weeks)

• Viral upper respiratory tract infections – the most common cause, typically self-limited and resolving within 1-3 weeks, though 10% persist beyond 25 days 2, 3
• Bronchiolitis – particularly in infants, with 90% cough-free by day 21 3
• Croup – presents with sudden-onset barking cough, stridor, and respiratory distress, most commonly caused by parainfluenza viruses 4
• Pneumonia – consider when high fever (≥39°C), respiratory distress, hypoxia, or focal findings are present 2, 3
• Foreign body aspiration – sudden onset without prodromal viral symptoms 4

Chronic Cough (≥4 Weeks)

The approach diverges based on whether the cough is specific (with pointers suggesting underlying disease) or non-specific (isolated dry cough without red flags). 1

Specific Cough Etiologies (Wet/Productive Cough or Red Flag Features)

Wet/productive cough differentials:

• Protracted bacterial bronchitis (PBB) – the most common cause of chronic wet cough in otherwise healthy children, responds to 2-week antibiotic course targeting Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis 1, 2
• Bronchiectasis – consider when wet cough persists despite appropriate antibiotics, or with digital clubbing, failure to thrive, or recurrent pneumonia 1
• Suppurative lung disease – chronic wet cough with systemic features 1

Other specific cough pointers requiring investigation:

• Asthma – when accompanied by documented wheeze on examination, exercise intolerance, nocturnal symptoms, or reversible airflow obstruction on spirometry 1, 2
• Aspiration lung disease – coughing with feeds, recurrent pneumonia, neurodevelopmental disorders 1
• Retained foreign body – sudden onset, unilateral findings, persistent despite treatment 1
• Cardiac anomalies – cough with exertional dyspnea, poor growth, or cardiac examination abnormalities 1
• Interstitial lung disease – cough with hypoxemia, digital clubbing, or diffuse crackles 1
• Tuberculosis – chronic cough with weight loss, night sweats, or TB exposure 1

Non-Specific Cough (Dry Cough Without Red Flags)

• Post-infectious cough – follows recent viral illness, typically resolves spontaneously within 8 weeks 2
• Upper airway cough syndrome (post-nasal drip) – chronic rhinorrhea, throat clearing, nasal congestion 2
• Habit cough/somatic cough syndrome – absent during sleep, barking quality, no response to medical therapy 5

Age-Specific Considerations

Preschool children (<6 years):

• Respiratory tract infections including PBB are diagnosed three times more often than in school-age children 5
• Episodic viral wheeze and recurrent obstructive bronchitis are common 5
• Spirometry typically unreliable in children <6 years 1

School-age children (≥6 years):

• Asthma and asthma-like conditions are diagnosed 3.5 times more often than in preschoolers, accounting for 36% of chronic cough diagnoses 5
• Spirometry with pre- and post-bronchodilator testing becomes feasible and recommended 1

Critical Red Flags Requiring Urgent Investigation

Specific cough pointers mandating immediate work-up: 1

• Coughing with feeds or vomiting
• Digital clubbing
• Failure to thrive or weight loss
• Hemoptysis
• Chest wall deformity
• Cardiac abnormalities on examination
• Focal lung findings (unilateral wheeze, crackles)
• Immune deficiency
• Neurodevelopmental abnormality
• Oxygen desaturation

Recommended Diagnostic Algorithm

For ALL Children with Chronic Cough (≥4 Weeks):

Mandatory initial investigations: 1, 2

1. Chest radiograph – to identify structural abnormalities, pneumonia, foreign body, or bronchiectasis
2. Spirometry (pre- and post-β2 agonist) – in children ≥6 years to assess for reversible airflow obstruction
3. Systematic classification – determine if cough is wet versus dry, and identify any specific cough pointers

Management Based on Cough Quality:

If WET/productive cough without other red flags: 1, 2

• Diagnose protracted bacterial bronchitis and treat with amoxicillin or amoxicillin-clavulanate for 2 weeks
• If cough persists, extend antibiotics for an additional 2 weeks
• If cough resolves with antibiotics, diagnosis of PBB is confirmed
• If cough persists despite 4 weeks of antibiotics, investigate for bronchiectasis or other suppurative lung disease

If DRY cough with asthma features (wheeze, exercise intolerance, nocturnal symptoms): 1, 2

• Trial of inhaled corticosteroids (beclomethasone 400 μg/day or equivalent) for 2-4 weeks maximum
• Re-evaluate at 2-4 weeks and discontinue if no response
• Do NOT diagnose asthma based on cough alone – chronic cough without wheeze is not associated with airway inflammation profiles suggestive of asthma 2, 3

If DRY cough without specific features (non-specific cough): 1, 2

• Often resolves spontaneously without specific treatment
• Address environmental tobacco smoke exposure
• Provide parental reassurance about expected illness duration
• Re-evaluate if persists beyond 8 weeks

Common Pitfalls to Avoid

• Never use over-the-counter cough and cold medications in children <6 years – they provide no benefit and may cause serious harm including 54 decongestant-related and 69 antihistamine-related fatalities in children <6 years between 1969-2006 3
• Never empirically treat for asthma unless documented wheeze or reversible airflow obstruction is present – atopy or positive allergy testing does not predict response to asthma therapy in isolated cough 2
• Never use codeine in children due to risk of respiratory distress 2
• Avoid empirical treatment for upper airway cough syndrome, gastroesophageal reflux, or asthma unless specific clinical features support these diagnoses 1, 2
• Do not assume colored nasal discharge indicates bacterial infection – it does not reliably distinguish viral from bacterial etiology 3

Evidence-Based Supportive Care

For acute cough in children >1 year: 2

• Honey is the only evidence-based first-line treatment, offering more relief than placebo, diphenhydramine, or no treatment
• Adequate hydration to thin secretions 2
• Acetaminophen or ibuprofen for fever and discomfort 2

Environmental modifications: 2, 3

• Eliminate tobacco smoke exposure – worsens respiratory symptoms and impairs secretion clearance
• Address parental expectations and anxiety about cough duration

When to Refer to Pediatric Pulmonology

Consider specialist referral for: 1, 2

• Failure to respond to appropriate initial management
• Concerning symptoms: hemoptysis, weight loss, persistent focal findings, digital clubbing
• Recurrent episodes despite appropriate treatment
• Suspected anatomical abnormality requiring bronchoscopy
• Chronic wet cough persisting beyond 4 weeks of appropriate antibiotics