What is the best treatment approach for an adult patient with chronic cough and no significant medical history?

Treatment of Chronic Cough in Adults

Begin empiric treatment with a first-generation antihistamine-decongestant combination to address upper airway cough syndrome (UACS), the most common cause of chronic cough, and proceed sequentially through asthma and gastroesophageal reflux disease (GERD) using an additive approach since multiple causes frequently coexist. 1, 2

Immediate Actions Before Starting Treatment

Stop ACE inhibitors immediately if the patient is taking them—no patient with troublesome cough should continue these medications, as cough typically resolves within days to 2 weeks (median 26 days) after discontinuation. 1, 2

Counsel and assist with smoking cessation if the patient smokes, as this alone resolves cough in the majority of patients within 4 weeks. 1, 2

Mandatory Baseline Investigations

• Obtain chest radiograph and spirometry in all patients to exclude serious pathology and assess for airflow obstruction. 1, 2, 3
• Assess cough severity using validated quality of life questionnaires or visual analog scales to monitor treatment response. 1, 2

Sequential Empiric Treatment Algorithm

Step 1: Treat Upper Airway Cough Syndrome (UACS)

Start with a first-generation antihistamine plus decongestant as initial empiric therapy, allowing at least 1-2 weeks for response. 1, 3

• If prominent upper airway symptoms (rhinosinusitis, postnasal drip) are present, add topical nasal corticosteroids. 1, 2
• UACS is the most common single cause of chronic cough and should always be addressed first. 1, 3

Step 2: Evaluate and Treat Asthma/Eosinophilic Bronchitis

If cough persists after treating UACS, perform bronchial provocation testing (methacholine challenge) in patients with normal spirometry to assess for bronchial hyperresponsiveness. 1, 3

• A negative methacholine challenge effectively excludes asthma. 1, 3
• If bronchial provocation testing is unavailable, administer a 2-week trial of oral corticosteroids (e.g., prednisone)—lack of response rules out eosinophilic airway inflammation. 1, 2
• If asthma is confirmed, treat with inhaled corticosteroids, bronchodilators, or leukotriene receptor antagonists. 1, 2

Step 3: Treat Gastroesophageal Reflux Disease (GERD)

If cough persists despite treatment for UACS and asthma, initiate intensive acid suppression with proton pump inhibitors (PPIs) and alginates for a minimum of 3 months. 1, 2

• GERD-related cough frequently occurs without gastrointestinal symptoms, making it a commonly missed diagnosis. 1, 2
• Failure to provide a full 3-month trial is a critical pitfall—shorter durations are inadequate for proper evaluation. 1, 2

Critical Treatment Principles

Use sequential AND additive therapy—maintain all partially effective treatments because more than one cause is present in the majority of patients. 1, 2

Optimize and verify compliance with each treatment before moving to the next step. 1, 2

Allow adequate treatment duration for each intervention—premature advancement through the algorithm leads to missed diagnoses. 1, 2

Management of Unexplained/Refractory Chronic Cough

If cough persists after systematic evaluation and treatment of UACS, asthma, and GERD:

Consider multimodality speech pathology therapy as a therapeutic trial for unexplained chronic cough. 1

Consider gabapentin (starting at 300 mg once daily, escalating to maximum 1,800 mg daily in divided doses as tolerated) after discussing potential side effects and risk-benefit profile, with reassessment at 6 months. 1

• Gabapentin has demonstrated improvement in quality of life in randomized controlled trials for refractory chronic cough. 1

Do NOT prescribe inhaled corticosteroids if bronchial provocation testing and eosinophil markers (sputum eosinophils, exhaled nitric oxide) are negative. 1

Do NOT prescribe PPIs if the workup for acid reflux is negative and there are no reflux symptoms. 1

When to Refer to Specialist

Refer to a specialist cough clinic if cough remains unexplained after completing the systematic evaluation and empiric treatment trials. 1, 2

• Chronic cough should only be labeled as idiopathic after thorough assessment at a specialty center. 1, 2
• Consider high-resolution CT if other targeted investigations are normal and specialist evaluation is planned. 1, 2
• Bronchoscopy is mandatory if foreign body inhalation is suspected. 1, 2

Common Pitfalls to Avoid

Never continue ACE inhibitors in patients with chronic cough, regardless of temporal relationship to cough onset. 1, 2

Never undertreat GERD—a full 3-month trial of intensive acid suppression is required, not shorter empiric trials. 1, 2

Never stop treatments prematurely—maintain all partially effective therapies in an additive fashion since multiple causes commonly coexist. 1, 2

Never diagnose idiopathic cough without completing the full systematic evaluation and ensuring adequate treatment duration for each potential cause. 1, 2