How should I evaluate and manage an adult with a cough, including assessment of duration, red‑flag symptoms, and treatment for acute versus chronic cough?

Evaluation and Management of Adult Cough

Classify cough by duration—acute (<3 weeks), subacute (3–8 weeks), or chronic (>8 weeks)—because this single determination immediately narrows your differential diagnosis and dictates the entire management pathway. 1

Initial Assessment: Red-Flag Screening

Screen every patient for red-flag symptoms that mandate urgent investigation before pursuing routine algorithmic workup 1:

• Hemoptysis – any blood in sputum requires immediate evaluation for malignancy, tuberculosis, bronchiectasis, or pulmonary embolism 1
• Smoker >45 years with new cough, change in cough, or coexisting voice disturbance – warrants urgent lung cancer evaluation 1
• Adults aged 55–80 years with ≥30 pack-year smoking history who currently smoke or quit within past 15 years – meets lung cancer screening criteria 1
• Prominent dyspnea at rest or at night – signals severe cardiopulmonary disease requiring immediate workup 1
• Fever, unintentional weight loss, or night sweats – suggests infection, malignancy, or tuberculosis 1
• Recurrent pneumonia – indicates structural lung disease, immunodeficiency, or aspiration 1
• Peripheral edema with weight gain – points to heart failure 1

In tuberculosis-endemic areas or high-risk populations, consider TB in all patients regardless of cough duration, even with normal chest radiographs 1.

Acute Cough (<3 weeks)

Common Causes and Management

Viral upper respiratory tract infection accounts for the vast majority of acute cough cases and resolves spontaneously within 3 weeks without specific treatment. 1

• Respiratory infections (most commonly viral) are the leading cause, followed by exacerbations of asthma or COPD, and pneumonia 1
• Provide reassurance and symptomatic care; over-the-counter preparations may offer subjective benefit but lack strong evidence for specific pharmacologic effects 1
• Consider bacterial pneumonia when fever, systemic symptoms, or abnormal lung auscultation are present 1
• Exclude pulmonary embolism in patients with risk factors (recent immobilization, surgery) who present with acute dyspnea and cough 1
• Assess for environmental or occupational irritant exposures in every patient 1

Follow-Up

• Routinely follow up at 4–6 weeks to ensure resolution 1
• Use validated cough severity or quality-of-life tools to quantify symptoms 1

Subacute Cough (3–8 weeks)

Primary Etiologies

Post-infectious cough is the most frequent cause, accounting for approximately 48% of subacute cough cases, and typically resolves without specific therapy. 1

• Post-infectious cough (48%) – usually self-limited 1
• Upper airway cough syndrome/UACS (33%) – from rhinosinus conditions 1
• Exacerbation of asthma or COPD (16%) – requires bronchodilator or corticosteroid therapy 1
• Non-asthmatic eosinophilic bronchitis (5%) – responds to inhaled corticosteroids 1
• Pertussis – suspect when paroxysmal coughing fits, post-tussive vomiting, or inspiratory "whoop" are present; initiate macrolide therapy immediately 1

Management Approach

• Obtain chest radiograph and spirometry if cough persists beyond 3 weeks 1
• Screen for red-flag symptoms as outlined above 1
• Consider tuberculosis in endemic areas or high-risk populations 1

Chronic Cough (>8 weeks)

Mandatory Baseline Investigations

Chest radiography and spirometry are non-negotiable baseline investigations for every adult with chronic cough. 1, 2, 3

• Chest radiograph – excludes mass lesions, infiltrates, bronchiectasis, interstitial lung disease, and cardiac abnormalities 1, 2, 3
• Spirometry with bronchodilator testing – detects airflow obstruction and assesses reversibility 1, 2, 3
• Quantify cough severity using visual analog scales or validated quality-of-life questionnaires to objectively monitor treatment response 1, 2, 3

Medication and Smoking Review

Discontinue any ACE inhibitor immediately; cough typically resolves within a median of 26 days (range up to 40 weeks) after cessation. 1, 2, 3, 4, 5

• Review all medications and stop ACE inhibitors or sitagliptin before pursuing extensive workup 1, 2, 3, 4
• Verify smoking status; if actively smoking, prioritize cessation as the primary intervention—most smoking-related coughs improve within 4 weeks 1, 2, 3
• Assess occupational and environmental exposures systematically 1, 2, 3

The "Big Four" Etiologies

Upper airway cough syndrome, asthma, gastroesophageal reflux disease, and non-asthmatic eosinophilic bronchitis account for >90% of chronic cough cases in non-smokers with normal or near-normal chest radiographs. 1, 2, 3, 6, 5

1. Upper Airway Cough Syndrome (UACS)

• Accounts for 18.6%–81.8% of chronic cough cases 1, 2, 3
• Associated symptoms include post-nasal drip sensation, throat clearing, nasal congestion, or chronic rhinitis 1, 2
• Initiate a first-generation antihistamine-decongestant combination as first-line empiric therapy 1, 4, 5
• When prominent upper-airway symptoms are present, add topical intranasal corticosteroid therapy 2

2. Asthma (Including Cough-Variant Asthma)

• Responsible for 14.6%–41.3% of chronic cough 1, 2, 3
• Cough may be the sole manifestation; normal spirometry does not exclude asthma 1, 2, 3
• Suspect when cough worsens at night, with cold air, exercise, or allergen exposure 2, 3
• No pulmonary function test can reliably exclude a cough that would respond to corticosteroids 2
• Initiate inhaled corticosteroids according to national asthma guidelines 2, 4
• A 2-week trial of oral prednisone (30–40 mg daily) differentiates eosinophilic airway inflammation; lack of improvement suggests a non-asthmatic cause 1, 2
• For refractory cough-variant asthma, add leukotriene-receptor antagonists rather than long-acting β-agonists 2

3. Gastroesophageal Reflux Disease (GERD)

• Implicated in 4.6%–85.4% of chronic cough cases 1, 2, 3
• Cough frequently occurs without classic gastrointestinal symptoms (heartburn, regurgitation) 1, 2, 7
• Acid suppression alone is no longer recommended as sole therapy 1, 3, 4
• Initiate intensive acid suppression with omeprazole 20–40 mg twice daily before meals for ≥8 weeks, combined with dietary and lifestyle modifications 2, 4
• Remove medications that aggravate reflux (bisphosphonates, nitrates, calcium-channel blockers, theophylline, progesterone) 2
• Add prokinetic agents (metoclopramide 10 mg three times daily) if response is inadequate 2, 4
• Clinical response may require 2–12 weeks 2, 4
• Consider antireflux surgery in carefully selected patients after comprehensive evaluation including 24-hour pH monitoring, esophageal manometry, and failed medical therapy 2

4. Non-Asthmatic Eosinophilic Bronchitis (NAEB)

• Accounts for 6.4%–17.2% of chronic cough 1, 2, 3
• Characterized by eosinophilic airway inflammation without airway hyperresponsiveness or variable airflow obstruction 1, 2, 3
• Inhaled corticosteroids are effective in reducing cough severity 2, 3

Critical Management Principle: Multiple Simultaneous Etiologies

Up to 67% of chronic cough patients have multiple concurrent causes; therefore, retain partially effective therapies and employ additive treatment strategies rather than sequential monotherapy. 1, 3, 4

Sequential Empiric Treatment Algorithm

1. First step: Trial of first-generation antihistamine-decongestant for UACS (4–6 weeks) 1, 4, 5
2. Second step: If UACS treatment fails, initiate inhaled corticosteroids for asthma; consider 2-week oral prednisone trial to confirm eosinophilic inflammation 1, 2, 4
3. Third step: Begin intensive GERD therapy with twice-daily PPI plus lifestyle modifications for ≥8 weeks 2, 4
4. Continue effective treatments while adding new therapies for partial responders 4

Advanced Investigations When Empiric Therapy Fails

If all empiric therapies are ineffective after 8 weeks, obtain high-resolution CT to evaluate for bronchiectasis, interstitial lung disease, or occult masses. 1, 2, 4

• High-resolution CT is indicated when targeted workup is normal and empiric treatments have failed 1, 2, 4
• Consider bronchoscopy for suspected foreign-body aspiration or when comprehensive workup remains inconclusive 2, 4
• Methacholine bronchial provocation testing is advised for patients with normal spirometry and no obvious etiology after referral to pulmonology 2

Refractory (Idiopathic) Chronic Cough

A diagnosis of idiopathic cough should be made only after comprehensive evaluation in a specialized cough clinic. 1, 2

• Consider cough hypersensitivity syndrome as the underlying mechanism 3, 6, 8
• Gabapentin trial starting at 300 mg once daily, escalating to maximum 1,800 mg daily in divided doses, may be effective 3, 6, 8
• Multimodality speech pathology therapy is an alternative approach 3, 6, 8
• Verify that all three top diagnoses (UACS, asthma, GERD) were properly treated with adequate duration before labeling as refractory 4

Follow-Up and Outcome Measurement

• Systematically re-evaluate at 4–6 weeks using validated cough-severity instruments to confirm treatment adherence and effectiveness 1, 2, 4
• Formally quantify treatment effects before abandoning a therapeutic trial 1, 2

Common Pitfalls to Avoid

• Assuming a single etiology – up to 40%–67% of patients have multiple concurrent causes requiring combination therapy 1, 3, 4
• Neglecting medication review – failure to discontinue ACE inhibitors or sitagliptin leads to unnecessary investigations 1, 2, 3, 4
• Relying solely on acid suppression for GERD-related cough – comprehensive management (lifestyle modification, dietary changes, possible prokinetics) is necessary 1, 2, 3, 4
• Not quantifying cough severity – objective assessment with validated tools is essential to monitor treatment response 1, 2, 3
• Inadequate trial duration – empiric therapeutic trials should be maintained for 4–6 weeks before deeming them ineffective 1, 2, 4
• Normal spirometry excludes asthma – cough-variant asthma often presents with normal baseline pulmonary function tests 1, 2, 3