What are the assessment and treatment options for a post-viral cough?

Post-Viral Cough Assessment and Treatment

For post-viral cough lasting 3-8 weeks, start with inhaled ipratropium bromide as first-line therapy, escalate to inhaled corticosteroids if quality of life is impaired and ipratropium fails, and reserve oral prednisone for severe paroxysms after excluding other common causes. 1, 2

Definition and Diagnostic Criteria

Post-infectious cough is defined as cough persisting for at least 3 weeks but not more than 8 weeks following an acute respiratory infection. 1, 2

Critical Timing Thresholds

• If cough persists beyond 8 weeks, reclassify as chronic cough and evaluate for alternative diagnoses including upper airway cough syndrome (UACS), asthma, gastroesophageal reflux disease, or other chronic conditions. 1, 2
• For cough lasting ≥2 weeks with paroxysms, post-tussive vomiting, or inspiratory whooping sound, suspect pertussis infection and obtain nasopharyngeal culture for confirmation. 1, 3

Pathogenetic Factors to Assess

Before initiating treatment, identify which mechanisms are most likely driving the cough 1:

• Postviral airway inflammation with bronchial hyperresponsiveness 1
• Mucus hypersecretion and impaired mucociliary clearance 1
• Upper airway cough syndrome (post-nasal drip) 1
• Underlying or unmasked asthma 1
• Gastroesophageal reflux disease 1

Treatment Algorithm

First-Line: Inhaled Ipratropium Bromide

Initiate a trial of inhaled ipratropium bromide as it has fair-level evidence for attenuating post-infectious cough. 1, 2

• This anticholinergic agent reduces mucus hypersecretion and has demonstrated efficacy in controlled trials. 2, 4
• A randomized controlled trial showed significant reduction in daytime cough severity (p=0.003) after 10 days of combined ipratropium and salbutamol versus placebo. 4

Second-Line: Inhaled Corticosteroids

When cough adversely affects quality of life and persists despite inhaled ipratropium, add inhaled corticosteroids. 1, 2

• The mechanism involves suppression of airway inflammation and bronchial hyperresponsiveness. 2
• This recommendation has expert opinion-level evidence but intermediate net benefit. 1

Third-Line: Oral Corticosteroids for Severe Cases

For severe paroxysms of post-infectious cough, prescribe prednisone 30-40 mg daily for a short, finite period after ruling out UACS, asthma, and GERD. 1, 2

• This carries low-level evidence with intermediate net benefit. 1
• This should only be used when other common causes have been excluded, as treating underlying conditions is more appropriate. 1

Last Resort: Central-Acting Antitussives

When other measures fail, consider codeine or dextromethorphan as central-acting antitussive agents. 1, 2

• These have expert opinion-level evidence with intermediate net benefit. 1
• Codeine showed no superiority over placebo in adult trials, and evidence for dextromethorphan is mixed. 5
• These agents cause sedation, constipation, and potential dependence. 6

What NOT to Do

Antibiotics Have No Role

Do not prescribe antibiotics for post-infectious viral cough, as the cause is not bacterial infection. 1, 2, 3

• This carries expert opinion-level evidence with no net benefit (Grade I). 1
• The only exceptions are confirmed bacterial sinusitis or early pertussis infection. 1

Avoid Ineffective Therapies

• Over-the-counter cough preparations have no good evidence for effectiveness in acute or post-infectious cough. 5
• Guaifenesin (expectorant) has conflicting evidence and questionable clinical relevance. 7, 5
• Antihistamines alone are ineffective unless combined with decongestants. 5

Special Consideration: Pertussis

When to Suspect

Suspect pertussis when cough lasts ≥2 weeks with paroxysms, post-tussive vomiting, or inspiratory whooping sound. 1, 3

Diagnostic Confirmation

• Obtain nasopharyngeal aspirate or Dacron swab for culture, as isolation of bacteria is the only certain diagnostic method. 1
• PCR is available but not universally standardized. 1

Treatment for Confirmed Pertussis

Prescribe macrolide antibiotics (azithromycin, clarithromycin, or erythromycin) and isolate patients for 5 days from treatment start. 1, 3

• Early treatment within the first few weeks diminishes coughing paroxysms and prevents disease spread. 1
• Treatment beyond this period is unlikely to benefit the patient. 1
• Long-acting β-agonists, antihistamines, corticosteroids, and pertussis immunoglobulin should NOT be used for pertussis, as there is no evidence of benefit. 1

Common Pitfalls to Avoid

• Failing to recognize when post-infectious cough transitions to chronic cough at 8 weeks, which requires different diagnostic evaluation. 2, 3
• Inappropriately prescribing antibiotics for non-bacterial post-viral cough, contributing to resistance and adverse effects. 3
• Overlooking underlying conditions (asthma, UACS, GERD) that may be contributing to persistent cough. 2
• Not considering pertussis in vaccinated patients, as breakthrough infections occur. 3
• Declaring treatment failure prematurely, as some interventions (particularly for GERD-related cough) may require 8-12 weeks for response. 3

Follow-Up and Monitoring

• Reassess patients within 4-6 weeks after initial evaluation. 2
• If cough persists beyond 8 weeks, initiate systematic evaluation for chronic cough causes including chest radiography, spirometry, and consideration of HRCT or bronchoscopy if indicated. 2, 3