What is the appropriate management for a patient with a persistent cough lasting three weeks, considering potential underlying pulmonary conditions such as asthma or COPD?

Management of Cough Lasting 3 Weeks

At 3 weeks duration, this cough has transitioned from acute to subacute, and you should obtain a chest X-ray to rule out pneumonia and other serious pathology, then initiate treatment with inhaled ipratropium bromide as first-line therapy for post-infectious cough. 1, 2

Immediate Diagnostic Steps

Obtain a chest X-ray now because cough lasting ≥3 weeks warrants imaging to exclude pneumonia, masses, structural abnormalities, interstitial disease, or congestive heart failure—particularly important if the patient has any vital sign abnormalities (heart rate ≥100 bpm, respiratory rate ≥24 breaths/min, temperature ≥38°C) or focal lung findings on examination. 1, 2

Rule Out Pertussis

Actively assess for pertussis by asking specifically about paroxysmal coughing, post-tussive vomiting, or inspiratory whooping sound. 1, 3 If any of these features are present, obtain a nasopharyngeal swab for pertussis PCR immediately and start azithromycin or clarithromycin without waiting for results, as early macrolide treatment reduces severity and transmission. 3

First-Line Treatment: Inhaled Ipratropium Bromide

Prescribe ipratropium bromide 2 puffs (36 mcg) four times daily as the only evidence-based first-line therapy for subacute post-infectious cough, with approximately 70% response rate and Grade B evidence. 1, 2, 3 This is superior to antibiotics, which have no role at this stage since the cause is not bacterial infection. 1, 2

• Expect response within 1-2 weeks of starting ipratropium. 2
• Do not prescribe antibiotics for post-infectious cough, as multiple trials show no benefit regardless of sputum color or duration. 1, 4

If Ipratropium Fails After 2 Weeks

Systematically evaluate and treat the three most common causes of persistent cough: upper airway cough syndrome (UACS), asthma/cough-variant asthma, and gastroesophageal reflux disease (GERD). 1, 2, 3

Upper Airway Cough Syndrome (UACS)

• Trial first-generation antihistamine/decongestant combination (e.g., chlorpheniramine 4 mg + pseudoephedrine 60 mg) for 1-2 weeks. 2, 3
• Look for postnasal drip, throat clearing, nasal congestion, or rhinorrhea on history. 1

Asthma or Cough-Variant Asthma

• Suspect if cough worsens at night, with cold air exposure, or with exercise. 1
• Perform spirometry with bronchodilator response or consider methacholine challenge testing. 1
• Trial inhaled corticosteroids (e.g., fluticasone 220 mcg twice daily) for 2-4 weeks if asthma is suspected, even with normal spirometry. 2

Gastroesophageal Reflux Disease (GERD)

• Initiate high-dose PPI therapy (omeprazole 20-40 mg twice daily before meals) for at least 8 weeks, as GERD-related cough requires prolonged treatment. 2, 3
• Consider adding prokinetic agents if initial PPI response is inadequate. 2

Symptomatic Management

Reserve central antitussives (codeine 15-30 mg every 4-6 hours or dextromethorphan 10-20 mg every 4 hours) only when other measures fail, as they have limited efficacy and potential for adverse effects. 1, 2

Red Flags Requiring Expanded Workup

Consider high-resolution CT chest, 24-hour esophageal pH monitoring, or bronchoscopy if: 2

• Cough persists beyond 8 weeks despite sequential treatment trials
• Systemic symptoms present (fever, weight loss, night sweats)
• Hemoptysis occurs
• History of tuberculosis, cancer, or immunosuppression
• Smoking history with concerning features

Follow-Up

Schedule reassessment in 4-6 weeks to evaluate treatment response and adjust therapy as needed. 3 Multiple causes frequently coexist (up to 25% of cases), so additive therapy targeting multiple etiologies may be necessary if single-agent trials fail. 1, 5