What is the recommended treatment for post infectious cough?

Treatment for Post-Infectious Cough

Start with inhaled ipratropium bromide as first-line therapy, as it has demonstrated efficacy in controlled trials for attenuating post-infectious cough. 1

Understanding Post-Infectious Cough

Post-infectious cough is defined as cough persisting for 3-8 weeks following an acute respiratory infection 1. The diagnosis is clinical and one of exclusion 2, 1. The underlying mechanism involves airway inflammation, bronchial hyperresponsiveness, mucus hypersecretion, and impaired mucociliary clearance 3.

If cough persists beyond 8 weeks, reclassify it as chronic cough and evaluate for other underlying causes such as upper airway cough syndrome (UACS), asthma, or gastroesophageal reflux disease (GERD). 2, 1

Treatment Algorithm

First-Line: Inhaled Ipratropium Bromide

• Prescribe inhaled ipratropium bromide 2-3 puffs four times daily as initial therapy 1, 3
• This has been shown in controlled trials to attenuate post-infectious cough with fewer systemic side effects 2, 3, 4
• Antibiotics have absolutely no role in treatment, as the cause is not bacterial infection 2, 1, 5

Second-Line: Inhaled Corticosteroids

• Consider inhaled corticosteroids (such as fluticasone or budesonide) when cough adversely affects quality of life AND persists despite ipratropium use 2, 1, 5
• The mechanism involves suppression of airway neutrophil inflammation and bronchial hyperresponsiveness 2, 1
• This approach is supported by animal models showing that Mycoplasma pneumoniae causes intense airway inflammation that can be suppressed by inhaled fluticasone 2

Third-Line: Oral Corticosteroids for Severe Cases

• For severe paroxysms that are persistently troublesome, prescribe prednisone 30-40 mg daily in the morning, tapering to zero over 2-3 weeks 2, 1, 5
• This should only be used after ruling out UACS, asthma, and GERD as alternative causes 2, 3
• The rationale is based on the speculation that post-infectious cough results from inflammation, with evidence showing neutrophil transmigration across bronchial epithelial cells 2

Fourth-Line: Central-Acting Antitussives

• Consider codeine (15-30 mg every 6 hours) or dextromethorphan (30 mg every 6 hours) when all other measures fail 2, 1, 5
• These should be reserved for when other treatments are unsuccessful 2, 3
• Evidence for dextromethorphan in acute respiratory tract infection cough is limited, with one study showing minimal benefit over placebo 6
• Codeine has demonstrated efficacy in chronic bronchitis but requires higher doses that may cause side effects 4, 7

Adjunctive Symptomatic Measures

• For patients over 1 year of age, recommend honey as a first-line symptomatic treatment 5
• Maintain adequate hydration (no more than 2 liters per day) 5
• Menthol lozenges or vapor may provide additional symptom relief 5
• Avoid lying flat on the back as this makes coughing ineffective 5

Critical Pitfalls to Avoid

• Do not prescribe antibiotics for post-infectious cough unless there is confirmed bacterial sinusitis or early Bordetella pertussis infection 2, 1, 5
• Do not continue treating as post-infectious cough if symptoms persist beyond 8 weeks—this requires reclassification and systematic evaluation for chronic cough causes 2, 1, 3
• Do not diagnose "unexplained cough" until completing systematic evaluation of UACS, asthma, and GERD with adequate treatment trials 3
• Failure to respond to treatment should prompt consideration of UACS due to rhinosinus diseases, asthma, or GERD 2

Special Consideration: Pertussis

• When cough lasts ≥2 weeks with paroxysms, post-tussive vomiting, or inspiratory whooping sound, consider pertussis infection 1, 3
• Nasopharyngeal culture is the gold standard for diagnosis 1
• Macrolide antibiotics are indicated for confirmed pertussis, with patient isolation for 5 days from treatment start 1

Monitoring

• Follow up within 4-6 weeks after initial evaluation 1
• If cough persists beyond 8 weeks despite treatment, initiate systematic evaluation for chronic cough causes including chest radiograph, trial of first-generation antihistamine/decongestant combination for UACS, and consideration of asthma or GERD 3