What is the appropriate management for a persistent cough?

Management of Persistent Cough

The management of cough depends critically on its duration: acute cough (<3 weeks) requires only symptomatic treatment and reassurance, while chronic cough (>8 weeks) demands systematic evaluation and treatment of underlying causes including upper airway cough syndrome, asthma, and GERD. 1

Initial Assessment and Red Flags

Start by determining cough duration and identifying serious conditions requiring immediate attention:

• Obtain chest X-ray immediately if: hemoptysis, breathlessness, prolonged fever with systemic illness, or vital sign abnormalities are present 2, 3
• Check medication list: ACE inhibitors cause cough that resolves within days to 2 weeks (median 26 days) after discontinuation 3
• Assess smoking status: Smoking cessation leads to resolution of chronic bronchitis within 4 weeks in most patients 3
• Screen for serious illness: Fever >4 days, new focal chest signs, dyspnea/tachypnea, night sweats, weight loss, or history of tuberculosis/cancer/AIDS require expanded workup 2, 3

Acute Cough (<3 Weeks Duration)

For acute cough, antibiotics should NOT be prescribed as the infection is viral, not bacterial—even with productive sputum or low-grade fever. 1

Symptomatic Treatment Options

• First-line home remedies: Honey and lemon mixtures are effective for benign viral cough 2, 4
• Dextromethorphan: Use 60 mg doses (not standard OTC 15-30 mg which are subtherapeutic) for maximum cough reflex suppression and prolonged relief 2, 4
• Antihistamine-decongestant combinations: First-generation antihistamine plus decongestant (e.g., brompheniramine/pseudoephedrine) decreases cough severity and hastens resolution 1
• NSAIDs: Naproxen has demonstrated benefit for cough in controlled studies 1
• Menthol inhalation: Provides acute but short-lived cough suppression 4

Important Caveats

• Avoid codeine or pholcodine: These have no greater efficacy than dextromethorphan but carry significantly greater adverse effects (drowsiness, nausea, constipation, physical dependence) 4
• Reassure patients: Acute bronchitis is self-limited and expected to resolve within 3 weeks 1
• Consider asthma: If patient has had two or more similar episodes in the past 5 years, underlying asthma should be considered 1

Subacute Cough (3-8 Weeks Duration)

If cough persists 3-8 weeks after an acute respiratory infection, treat as post-infectious cough with inhaled ipratropium bromide as first-line therapy. 1, 3

• Inhaled ipratropium: First-line treatment for post-infectious cough 1, 3
• Inhaled corticosteroids: If ipratropium fails 3
• Short course oral prednisone: For severe paroxysms after ruling out other causes 3
• Reassurance: Spontaneous resolution is expected 1

Chronic Cough (>8 Weeks Duration)

For chronic cough, use a systematic sequential approach treating the three most common causes: upper airway cough syndrome (UACS), asthma, and GERD—in that order. 2, 3

Step 1: Treat Upper Airway Cough Syndrome (UACS)

• Clinical pointers: Nasal discharge, throat clearing, postnasal drip sensation, nasal congestion, or rhinorrhea 3
• Treatment: First-generation antihistamine-decongestant combination for 1-2 weeks 3
• If no response: Proceed to Step 2 3

Step 2: Evaluate and Treat Asthma

• Clinical pointers: Cough worsens at night, with cold air exposure, or with exercise 3
• Diagnostic testing: Spirometry with bronchodilator response or bronchoprovocation challenge 3
• Treatment timeline: Response to bronchodilators occurs within 1 week, but complete resolution may take up to 8 weeks 3
• If no response: Proceed to Step 3 3

Step 3: Treat GERD

• Treatment regimen: High-dose PPI therapy, dietary modifications, and lifestyle changes 3
• Critical timing: Response may take 2 weeks to several months; some patients require 8-12 weeks before improvement 3
• Consider prokinetic agents: Add metoclopramide and rigorous adherence to dietary measures before labeling as medically refractory GERD 2
• If no response: Proceed to advanced testing 3

Step 4: Advanced Diagnostic Testing

Only proceed after adequate therapeutic trials of UACS, asthma, and GERD have failed. 3

• High-resolution CT chest: Evaluate for bronchiectasis, interstitial lung disease, or occult masses 2, 3
• 24-hour esophageal pH monitoring: If empiric GERD therapy failed 3
• Bronchoscopy: Look for endobronchial lesions, sarcoidosis, eosinophilic bronchitis, or occult infection 2, 3
• Consider tuberculosis: In endemic areas, obtain expectorated or induced sputum samples with acid-fast staining 2

Step 5: Refractory Chronic Cough

Only diagnose unexplained cough after completing systematic evaluation and adequate therapeutic trials of all common causes. 3

• Gabapentin trial: Start at 300 mg once daily, escalate as tolerated to maximum 1,800 mg daily in divided doses 3
• Speech pathology therapy: Multimodality approach is a reasonable alternative 3
• Low-dose morphine: Consider only for severe cases but carries addiction risk 3
• Specialist referral: Appropriate before making diagnosis of unexplained cough 2

Common Pitfalls to Avoid

• Do not prescribe antibiotics reflexively based on productive sputum or low-grade fever—these are typical viral features 1
• Do not miss underlying asthma in patients with recurrent episodes 1
• Do not fail to recognize the 3-week and 8-week thresholds that change the diagnostic approach and treatment strategy 1
• Do not overlook pertussis in patients with characteristic paroxysmal cough, especially with household contacts 1
• Do not continue antitussive therapy beyond 14 days without reassessing for alternative diagnoses 4
• Do not use standard OTC dextromethorphan doses (15-30 mg)—they are subtherapeutic 4