What are the evaluation and treatment options for a constant cough?

Evaluation and Management of Constant Cough

For adults with constant (chronic) cough, begin with chest radiograph and spirometry, discontinue ACE inhibitors if present, and initiate sequential empiric treatment targeting the three most common causes: upper airway cough syndrome (UACS), asthma, and gastroesophageal reflux disease (GERD), as these account for the vast majority of cases when treated systematically. 1

Initial Mandatory Evaluation

Obtain chest radiograph and spirometry in all patients—these are mandatory baseline tests. 1 The chest radiograph rules out serious pathology including malignancy, pneumonia, and structural lung disease, while spirometry identifies obstructive airway disease. 1

Perform a detailed history focusing on:

• ACE inhibitor use (discontinue immediately if present, as this alone may resolve the cough) 1, 2
• Smoking status (counsel cessation, which resolves cough within 4 weeks) 1, 2
• Occupational exposures 1
• Symptoms suggesting upper airway disease, asthma, or reflux 1

Assess cough severity and quality of life impact using validated instruments or visual analogue scores. 1

Sequential Treatment Algorithm for Common Causes

Chronic cough in adults is defined as lasting more than 8 weeks. 1 The character, timing, or presence of sputum should NOT guide your diagnostic approach—these features have no diagnostic value. 1

First: Treat Upper Airway Cough Syndrome (UACS)

Begin with a first-generation antihistamine/decongestant combination. 2, 3 UACS (formerly called postnasal drip syndrome) is diagnosed by combination of symptoms, physical findings, and response to therapy—no single pathognomonic finding exists. 1

If prominent upper airway symptoms are present, add topical nasal corticosteroids. 1

Second: Treat Asthma/Eosinophilic Airway Disease

"Silent" asthma or cough-variant asthma can present with cough alone, without wheezing or dyspnea. 1 If spirometry is normal but asthma is suspected, perform bronchial provocation testing. 1

Initiate treatment with inhaled corticosteroids combined with long-acting β-agonists. 2, 3 For nonasthmatic eosinophilic bronchitis (NAEB), inhaled corticosteroids alone are first-line treatment. 2, 3

A 2-week trial of oral corticosteroids can exclude eosinophilic airway inflammation if there is no response. 1

Third: Treat Gastroesophageal Reflux Disease (GERD)

"Silent GERD" commonly causes chronic cough without any gastrointestinal symptoms. 1 Failure to consider GERD is a common reason for treatment failure. 1

Initiate intensive acid suppression with proton pump inhibitors and alginates for a minimum of 3 months. 1, 2 This extended duration is critical—shorter trials often fail because reflux-related cough takes time to resolve.

Add prokinetic therapy if there is little or no response to PPI therapy alone. 2

Multiple Causes Are Common

Most chronic cough cases have multiple contributing factors—do not stop after identifying one cause. 2, 3 The sequential approach should be additive, treating all identified contributors simultaneously. 3

When to Pursue Advanced Testing

If cough persists despite 4-6 weeks of empiric treatment for the common causes:

• Consider high-resolution CT scan 1
• Perform bronchoscopy if foreign body aspiration is suspected 1
• Refer to a pulmonologist or cough specialist 2

Symptomatic Treatment for Refractory Cough

When cough interferes with daily activities or sleep despite treating underlying causes:

• Consider codeine or dextromethorphan-containing antitussives for symptomatic relief 2
• Low-dose morphine may be used for idiopathic chronic cough refractory to other treatments 2
• Honey may provide symptomatic relief in patients over 1 year of age 2, 3

Note that most over-the-counter cough preparations lack evidence of specific pharmacological effect, though patients report subjective benefit. 1 Newer non-sedating antihistamines are ineffective for cough. 3

Critical Pitfalls to Avoid

• Never continue ACE inhibitors in a patient with troublesome cough—switch to another drug class immediately. 1
• Do not rely on cough characteristics (wet vs. dry, timing, quality) to guide diagnosis. 1
• Do not treat only one potential cause—chronic cough typically has multiple contributors. 2, 3
• Do not perform extensive testing before trying empiric treatment for the common triad (UACS, asthma, GERD). 1
• Significant sputum production usually indicates primary lung pathology and requires different evaluation. 1

Red Flags Requiring Immediate Investigation

Pursue urgent evaluation if any of the following are present:

• Hemoptysis 1
• Prominent systemic illness 1
• Suspicion of lung cancer 1
• Suspicion of inhaled foreign body 1

Special Populations

In children ≤14 years, chronic cough is defined as daily cough lasting more than 4 weeks, and common adult causes should NOT be presumed to apply. 1 Use pediatric-specific management protocols. 2