What is the appropriate evaluation and management for a patient presenting with a chronic cough lasting 4 weeks?

Evaluation and Management of a 4-Week Cough

A cough lasting 4 weeks falls into the subacute category (3-8 weeks) in adults and requires systematic evaluation with chest radiography, assessment for red flag symptoms, and consideration of postinfectious cough as the most likely etiology. 1

Classification by Duration

• Adults: A 4-week cough is classified as subacute (3-8 weeks duration), which sits between acute (<3 weeks) and chronic (>8 weeks) cough 1
• Children ≤14 years: A 4-week cough is classified as chronic and warrants more aggressive evaluation due to risk of serious underlying conditions (bronchiectasis, aspiration, cystic fibrosis found in up to 18-30% of cases) 1

Immediate Assessment

Screen for Red Flags First

• Immediately evaluate for hemoptysis, unexplained weight loss, fever, dysphagia, or digital clubbing—these require urgent workup and cannot be dismissed as postinfectious 1, 2
• Obtain a chest radiograph in all patients to exclude serious pathology 1, 3

Medication Review

• Discontinue ACE inhibitors immediately if the patient is taking one—ACE inhibitor cough can persist for weeks after starting the medication 1, 3
• Also discontinue sitagliptin if applicable 1

Environmental and Occupational History

• Assess for smoking, secondhand smoke exposure, occupational irritants, and environmental triggers 1, 2

Age-Specific Management Pathways

For Adults with Subacute Cough (4 weeks)

Most Common Cause: Postinfectious cough (48.4%), followed by post-nasal drip syndrome/upper airway cough syndrome (33.2%), asthma (15.8%), and nonasthmatic eosinophilic bronchitis (5.4%) 1

Treatment Approach:

• Trial inhaled ipratropium for postinfectious cough as first-line symptomatic treatment 2
• Do NOT use antibiotics unless there is confirmed bacterial sinusitis or pertussis 2
• If upper airway cough syndrome is suspected: trial a decongestant plus first-generation antihistamine 3, 4
• Use a validated cough severity tool to objectively track response 1, 2
• Schedule follow-up in 4-6 weeks—if cough persists beyond 8 weeks, it becomes chronic and requires the chronic cough algorithm 1, 2

For Children ≤14 Years with 4-Week Cough

Critical Distinction: Determine if the cough is wet/productive versus dry, as this fundamentally changes management 1, 2

If Wet/Productive Cough (Without Specific Pointers):

• Immediately prescribe 2 weeks of antibiotics targeting Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis (amoxicillin-clavulanate based on local sensitivities) 1, 2
• If cough resolves: diagnose as protracted bacterial bronchitis (PBB) 1
• If cough persists after 2 weeks: extend antibiotics for an additional 2 weeks 1, 2
• If cough persists after 4 weeks total: perform flexible bronchoscopy with quantitative cultures and/or chest CT 1

If Wet Cough WITH Specific Pointers:

• Specific pointers include: coughing with feeding, digital clubbing, failure to thrive, recurrent pneumonia 1
• Immediately pursue extensive workup: flexible bronchoscopy, chest CT, swallow evaluation, immunologic assessment to exclude bronchiectasis, aspiration, cystic fibrosis, or immunodeficiency 1

If Dry Cough:

• Obtain chest radiograph and spirometry (if child >6 years old) 1
• Consider asthma as primary differential—trial inhaled bronchodilators/corticosteroids if clinically suspected 1, 4
• Do NOT empirically treat for GERD unless the child has gastrointestinal symptoms (recurrent regurgitation, heartburn, epigastric pain) 1

What NOT to Do

• Do not use over-the-counter cough suppressants (dextromethorphan) in children under 6 years 2, 5
• Do not use acid suppression therapy for isolated chronic cough without GI symptoms in children—this has no evidence of benefit and potential harm 1
• Do not assume adult causes (GERD, upper airway cough syndrome, asthma) apply to children—pediatric etiologies differ significantly 1

Follow-Up Strategy

• Mandatory follow-up at 4-6 weeks after initial evaluation to reassess response 1, 2
• Use validated cough severity or quality-of-life instruments to objectively measure improvement 1, 2
• If cough persists beyond 8 weeks in adults, transition to chronic cough algorithm addressing upper airway cough syndrome, asthma, GERD, and nonasthmatic eosinophilic bronchitis 1, 4

Common Pitfalls

• Dismissing 4-week cough as "just post-viral" in children without proper evaluation—serious progressive lung disease is found in 18-30% of these cases 1
• Empirically treating GERD without GI symptoms—this wastes time and exposes patients to unnecessary medication risks, particularly in children 1
• Failing to discontinue ACE inhibitors early—this is a reversible cause that should be addressed immediately 1, 3
• Not using objective cough assessment tools—subjective assessment alone is unreliable for tracking treatment response 1, 2