What are the differential diagnoses and initial evaluation for cough and shortness of breath in a pediatric patient (0‑18 years)?

Differential Diagnoses for Cough and Shortness of Breath in Pediatric Patients

Critical Immediate Assessment

Assess for life-threatening conditions first: respiratory distress (respiratory rate >50 breaths/min in children or >70 breaths/min in infants, accessory muscle use, oxygen saturation <92%), foreign body aspiration (sudden onset with unilateral wheeze), and pertussis (paroxysmal cough with post-tussive vomiting or inspiratory "whoop"). 1, 2, 3

Red Flag Features Requiring Urgent Evaluation

• Respiratory distress indicators: Tachypnea (>50 breaths/min in children, >70 breaths/min in infants), use of accessory muscles, oxygen saturation <92%, inability to speak in full sentences, grunting, or cyanosis 2, 3, 4
• Foreign body aspiration: Sudden onset cough with unilateral wheeze or asymmetric breath sounds 3
• Pertussis: Paroxysmal cough with post-tussive vomiting or inspiratory "whoop," especially with incomplete vaccination 1, 3
• Pneumonia: High fever (≥39°C), tachypnea, hypoxia, or focal crackles on auscultation 3
• Hemoptysis: At any age warrants immediate specialist referral 2

Age-Dependent Differential Diagnoses

Infants and Young Children (<2 years)

Common etiologies in this age group differ substantially from adults and include viral bronchiolitis, protracted bacterial bronchitis, and aspiration syndromes rather than asthma or GERD. 1

• Viral bronchiolitis: Most common cause of acute cough with wheeze in infants; 90% resolve by day 21 3, 4
• Protracted bacterial bronchitis (PBB): Wet/productive cough lasting >4 weeks; most common diagnosis in prospective studies (41% of cases) 1, 2
• Aspiration: Cough associated with feeding, failure to thrive, or recurrent pneumonia 2, 3
• Foreign body inhalation: Sudden onset, unilateral findings, history may be unknown 1
• Congenital airway abnormalities: Tracheomalacia, vascular rings; consider if stridor or persistent wheeze 1

School-Age Children (2-14 years)

The most common etiologies in prospective studies are asthma/asthma-like conditions (16-25%), protracted bacterial bronchitis (23-41%), and post-viral cough that resolves spontaneously (14-22%). 1

• Asthma: Requires additional features beyond isolated cough—recurrent wheeze, nocturnal symptoms, exercise intolerance, reversible airflow obstruction on spirometry 1, 3
• Protracted bacterial bronchitis: Wet cough >4 weeks responding to 2-4 weeks of antibiotics targeting Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis 1, 3
• Post-viral cough: Dry cough following upper respiratory infection; 90% resolve by 3 weeks 1, 3
• Pertussis: Paroxysmal cough, post-tussive vomiting, inspiratory whoop; high sensitivity for paroxysmal cough (93.2%) 1
• Mycoplasma pneumonia: Persistent dry cough with atypical pneumonia features 1

Adolescents (>14 years)

Adolescents may be managed using adult chronic cough algorithms, though the transition age is not precisely defined. 1

• Asthma: More reliably diagnosed with spirometry and bronchodilator response 1, 3
• Upper airway cough syndrome (UACS): Uncommon in prospective pediatric studies; only common in Turkish cohorts 1
• Gastroesophageal reflux disease (GERD): Controversial cause in children; not common in high-quality prospective studies 1

Systematic Evaluation Based on Cough Duration

Acute Cough (<4 weeks)

Most acute coughs are viral and self-limited, resolving within 7-10 days; 90% resolve by day 21. 1, 3, 4

• Viral upper respiratory tract infection: Most common cause; supportive care only 3, 4
• Acute bronchitis: Self-limited; antibiotics not indicated 1, 3
• Pneumonia: Consider if high fever, tachypnea, hypoxia, or focal findings 3
• Pertussis: Assess for classical triad (paroxysmal cough, post-tussive vomiting, inspiratory whoop) 1

Chronic Cough (≥4 weeks)

At 4 weeks, systematic evaluation is mandatory using pediatric-specific algorithms; common adult causes (chronic bronchitis, idiopathic cough, GERD) are NOT presumed common in children. 1

Mandatory Initial Investigations

• Chest radiograph: Identify structural abnormalities, pneumonia, foreign body, or bronchiectasis 1, 3
• Spirometry (pre- and post-bronchodilator): In children ≥6 years who can cooperate reliably 1, 3
• Classify cough as wet/productive versus dry: Guides subsequent management 1, 3

Wet/Productive Cough Algorithm

• First-line treatment: 2-week course of amoxicillin or amoxicillin-clavulanate targeting common respiratory bacteria 1, 3, 4
• If cough persists after 2 weeks: Extend antibiotics for additional 2 weeks 1, 3
• If cough persists after 4 weeks of antibiotics: Refer to pediatric pulmonologist for bronchoscopy, chest CT, immunologic evaluation, and assessment for bronchiectasis, aspiration, cystic fibrosis, or immunodeficiency 1, 2, 3

Dry/Nonproductive Cough Algorithm

• Watchful waiting: Most resolve spontaneously without specific treatment 1, 3
• Evaluate for asthma ONLY if additional features present: Recurrent wheeze, nocturnal symptoms, exercise intolerance, family history of atopy, or reversible airflow obstruction on spirometry 1, 3
• Do NOT diagnose asthma based on isolated cough alone: Majority of children with isolated chronic cough lack asthma-related airway inflammation 1, 3, 4

Less Common but Important Differentials

Structural and Congenital Abnormalities

• Tracheomalacia/bronchomalacia: Expiratory wheeze, worse with crying or agitation 1
• Vascular rings: Stridor, dysphagia, chronic cough 1
• Tracheoesophageal fistula: Cough with feeding, recurrent pneumonia 1, 2

Chronic Suppurative Lung Disease

• Bronchiectasis: Chronic wet cough, digital clubbing, failure to thrive, recurrent infections 1, 2
• Cystic fibrosis: Failure to thrive, chronic wet cough, recurrent infections, family history 1, 3
• Primary ciliary dyskinesia: Chronic wet cough, recurrent sinusitis, situs inversus 1

Immunodeficiency

• Recurrent infections, failure to thrive, chronic wet cough: Warrants immunologic workup 1, 2

Cardiac Causes

• Congestive heart failure: Tachypnea, hepatomegaly, poor feeding 1
• Pulmonary hypertension: Exertional dyspnea, syncope 1

Obstructive Sleep Apnea (OSA)

• Chronic dry cough with snoring, witnessed apneas, tonsillar hypertrophy: Manage according to sleep guidelines 1

Critical Pitfalls to Avoid

Do NOT extrapolate adult chronic cough etiologies to children; common adult causes (chronic bronchitis, idiopathic cough, GERD, UACS) are NOT common in pediatric prospective studies. 1

• Over-diagnosing asthma: Isolated cough without wheeze, dyspnea, or reversible obstruction is rarely asthma 1, 3, 4
• Empirical treatment without specific features: Do NOT prescribe asthma medications, GERD treatment, or UACS therapy unless specific clinical features support these diagnoses 1, 3
• Prescribing over-the-counter cough medications: No proven efficacy in children <6 years; risk of serious adverse events including fatalities 4
• Prescribing codeine: Risk of serious respiratory depression; contraindicated 3
• Ignoring environmental tobacco smoke: Worsens respiratory symptoms and impairs secretion clearance 1, 3, 4
• Delayed recognition of foreign body: Can result in permanent lung damage 1

Referral Criteria to Pediatric Pulmonology

Refer immediately if any of the following are present: chronic wet cough >4 weeks unresponsive to antibiotics, failure to thrive or digital clubbing, oxygen requirement at 2 years of age, recurrent hospitalizations, cough with feeding suggesting aspiration, hemoptysis, or diagnostic uncertainty after appropriate evaluation. 2