How should I evaluate and manage a dry (non‑productive) cough in an adult?

Evaluation and Management of Dry Cough in Adults

For an adult presenting with dry (non-productive) cough, immediately determine duration: if less than 3 weeks, reassure and provide symptomatic care; if 3–8 weeks, consider post-infectious cough or upper airway cough syndrome; if greater than 8 weeks, obtain mandatory chest radiograph and spirometry, then initiate sequential empiric trials targeting upper airway cough syndrome, asthma, and gastroesophageal reflux disease. 1

Initial Triage by Duration

• Acute dry cough (< 3 weeks) is most commonly viral upper respiratory infection and is self-limiting; provide reassurance and symptomatic management unless red-flag features are present. 1, 2
• Sub-acute dry cough (3–8 weeks) is most frequently post-infectious (≈48% of cases) and typically resolves without specific therapy. 1
• Chronic dry cough (> 8 weeks) requires systematic investigation and empiric treatment trials. 1, 3

Red-Flag Screening (Mandatory at Every Visit)

Immediately escalate evaluation if any of the following are present:

• Hemoptysis – suggests malignancy, tuberculosis, bronchiectasis, or pulmonary embolism. 1
• Unintentional weight loss or fever – raises concern for malignancy, tuberculosis, or chronic infection. 1, 4
• Significant dyspnea at rest or nocturnal dyspnea – may indicate severe cardiopulmonary disease. 1
• New cough in a smoker > 45 years or ≥ 30 pack-year history (age 55–80) – meets lung cancer screening criteria. 1
• Hoarseness – consider laryngeal pathology or recurrent laryngeal nerve involvement. 1
• Recurrent pneumonia – suggests structural lung disease, immunodeficiency, or aspiration. 1

Medication and Exposure Review

• Discontinue any ACE inhibitor immediately; cough resolves in a median of 26 days (up to 40 weeks) after cessation. 1
• Verify smoking status; if active, prioritize cessation as most smoking-related coughs improve within 4 weeks. 1, 3
• Assess occupational and environmental exposures systematically (dust, fumes, chemicals, mold, pets). 1, 3

Mandatory Baseline Investigations for Chronic Dry Cough

• Chest radiograph is non-negotiable to exclude mass, infiltrate, interstitial disease, bronchiectasis, and cardiac abnormalities. 1, 3
• Spirometry with bronchodilator response is required to detect airflow obstruction and assess reversibility. 1, 3
• Quantify cough severity using visual analog scales or validated quality-of-life questionnaires to monitor treatment response objectively. 1, 3

The "Big Three" Etiologies (Account for > 90% of Chronic Dry Cough)

1. Upper Airway Cough Syndrome (UACS)

• UACS is the single most common cause, accounting for 19%–82% of chronic cough cases. 1
• Symptoms include post-nasal drip sensation, frequent throat clearing, nasal congestion, or chronic rhinitis. 1, 3
• Initiate a first-generation antihistamine-decongestant combination (e.g., brompheniramine-pseudoephedrine) for several weeks. 1
• When prominent upper-airway symptoms are present, add topical intranasal corticosteroid. 1

2. Asthma (Including Cough-Variant Asthma)

• Asthma underlies 15%–41% of chronic dry cough and may present as cough alone without wheezing or dyspnea. 1, 5
• Normal spirometry does not exclude asthma; cough-variant asthma often has normal baseline pulmonary function. 1
• If spirometry is normal and UACS treatment fails, perform methacholine bronchial provocation testing to detect airway hyperresponsiveness. 1, 3
• Initiate inhaled corticosteroids according to national asthma guidelines. 1
• A 2-week trial of oral prednisone 30–40 mg daily can differentiate eosinophilic airway inflammation; lack of improvement suggests a non-asthmatic cause. 1

3. Gastroesophageal Reflux Disease (GERD)

• GERD contributes to 5%–85% of chronic cough and frequently occurs without heartburn or regurgitation. 1, 5
• Intensive acid suppression with a proton-pump inhibitor (omeprazole 20–40 mg twice daily before meals) plus alginate for ≥ 3 months is required; clinical response may take 2–12 weeks. 1
• Add dietary and lifestyle modifications: elevate head of bed, avoid late meals, eliminate reflux-exacerbating medications (bisphosphonates, nitrates, calcium-channel blockers, theophylline). 1
• Consider adding prokinetic agent (metoclopramide 10 mg three times daily) if response is inadequate. 1

Non-Asthmatic Eosinophilic Bronchitis (NAEB)

• NAEB accounts for 6%–17% of chronic dry cough and is characterized by eosinophilic airway inflammation without airway hyperresponsiveness or variable airflow obstruction. 1, 3
• Inhaled corticosteroids are effective in reducing cough severity. 1

Multiple Simultaneous Etiologies

• Up to 67% of chronic cough patients have more than one contributing cause; therefore, retain partially effective therapies and employ additive treatment strategies rather than sequential monotherapy. 1
• Cough resolves only after all contributing factors are addressed. 1

Follow-Up and Treatment Duration

• Schedule re-evaluation at 4–6 weeks to assess cough severity using validated instruments and verify treatment adherence before abandoning a therapeutic trial. 1, 3
• Each empiric trial should be maintained for an adequate duration: GERD requires ≥ 3 months, UACS requires several weeks, asthma requires 2–4 weeks. 1, 3

Advanced Evaluation When Empiric Therapy Fails

• If all three common causes have been addressed without improvement after 8 weeks, obtain high-resolution CT of the chest to evaluate for bronchiectasis, interstitial lung disease, or occult masses. 1
• Consider bronchoscopy to assess for endobronchial lesions, sarcoidosis, eosinophilic bronchitis, or occult infection. 1
• Refer to a specialist cough clinic for comprehensive evaluation when the condition remains undiagnosed after systematic work-up. 1, 3

Refractory (Idiopathic) Cough

• A diagnosis of idiopathic cough should be made only after comprehensive evaluation in a specialized cough clinic has excluded all treatable causes. 1
• Consider cough hypersensitivity syndrome and manage with gabapentin or pregabalin plus a trial of speech therapy. 4

Common Pitfalls to Avoid

• Assuming a single etiology – multiple concurrent causes are present in up to 67% of patients; combination therapy is often required. 1
• Neglecting medication review – failure to discontinue ACE inhibitors before extensive work-up leads to unnecessary investigations. 1
• Relying solely on acid suppression for GERD – comprehensive management (lifestyle modification, dietary changes, possible prokinetics) is necessary. 1
• Inadequate trial duration – empiric therapeutic trials must be maintained for 4–6 weeks before deeming them ineffective. 1
• Interpreting normal spirometry as excluding asthma – cough-variant asthma frequently presents with normal baseline pulmonary function; methacholine challenge is required. 1

Over-the-Counter Cough Suppressants

• Dextromethorphan should not be used if the patient has chronic cough that occurs with smoking, asthma, or emphysema, or if cough occurs with too much phlegm. 6
• Stop dextromethorphan and seek medical evaluation if cough lasts more than 7 days, comes back, or occurs with fever, rash, or headache. 6