What is the systematic approach to evaluating and managing a chronic cough lasting more than eight weeks?

Systematic Approach to Chronic Cough in Adults

Definition and Initial Red-Flag Assessment

Chronic cough is defined as cough lasting more than 8 weeks in adults, and your first priority is to identify red-flag features that require urgent investigation before proceeding with the systematic algorithm. 1, 2

Immediate Red Flags Requiring Urgent Work-Up

• Hemoptysis mandates immediate investigation for malignancy, tuberculosis, or other life-threatening conditions 2, 3
• Adults over 45 years who smoke with new-onset cough require urgent evaluation for lung cancer 2
• Unintentional weight loss, fever, or night sweats suggest serious underlying disease including malignancy or infection 2, 3
• Prominent dyspnea at rest or at night indicates potentially severe cardiopulmonary pathology 2, 3
• Hoarseness or difficulty swallowing may signal laryngeal pathology or malignancy 2, 4

Mandatory Baseline Investigations

Every patient with chronic cough must undergo chest radiography and spirometry before empiric treatment begins—these are non-negotiable first steps. 1, 2, 3

• Chest radiograph excludes infectious, inflammatory, and malignant thoracic disease 1, 2, 4
• Spirometry detects obstructive airway pathology and guides asthma evaluation 1, 2, 3
• Cough severity quantification using visual analog scales or validated quality-of-life questionnaires establishes baseline and tracks treatment response 1, 2, 4

Critical Medication and Exposure Review

Before proceeding with diagnostic testing, discontinue ACE inhibitors and assess smoking status—these reversible causes resolve cough within 4 weeks. 2, 3

• ACE inhibitor-induced cough resolves within a median of 26 days after discontinuation 2
• Smoking-related cough typically resolves within 4 weeks of cessation 2, 3
• Occupational and environmental exposures must be systematically evaluated in all patients 1, 2, 3

Systematic Empiric Treatment Algorithm

The four conditions—upper airway cough syndrome (UACS), asthma, gastroesophageal reflux disease (GERD), and nonasthmatic eosinophilic bronchitis (NAEB)—account for more than 90% of chronic cough cases, and you must address them sequentially and additively. 2, 4, 5

Step 1: Upper Airway Cough Syndrome (UACS)

UACS is the single most common cause, responsible for 18.6–81.8% of cases, so begin treatment here first. 2, 3

• Initiate first-generation antihistamine-decongestant combination as first-line therapy 4
• Topical nasal corticosteroids are recommended when prominent upper airway symptoms are present 2
• Assess response within 4–6 weeks using validated cough severity measures 2, 4

Step 2: Asthma (Including Cough-Variant Asthma)

If UACS treatment fails or provides only partial relief, evaluate for asthma, which accounts for 14.6–41.3% of chronic cough cases and may present with cough as the sole manifestation. 2, 4

• Normal spirometry does not exclude asthma-related cough—cough may be the only symptom without airflow obstruction 2
• Methacholine bronchial provocation testing is required for patients with normal spirometry and no obvious etiology after referral to a pulmonologist 1, 2
• Initiate inhaled corticosteroids according to national asthma guidelines 2
• A 2-week trial of oral prednisone (30–40 mg daily) differentiates eosinophilic airway inflammation; lack of improvement suggests a non-asthmatic cause 2
• For refractory cough-variant asthma, add leukotriene-receptor antagonists rather than long-acting β-agonists 2

Step 3: Gastroesophageal Reflux Disease (GERD)

GERD contributes to 4.6–85.4% of chronic cough and often occurs without gastrointestinal symptoms, requiring intensive and prolonged acid suppression. 2

• Intensive acid suppression with proton-pump inhibitor (omeprazole 20–40 mg twice daily before meals) plus alginates for a minimum of 3 months is required 2
• Dietary and lifestyle modifications must accompany pharmacologic therapy, including removal of medications that aggravate reflux (bisphosphonates, nitrates, calcium-channel blockers, theophylline, progesterone) 2
• Clinical response may require 2 weeks to 12 weeks, so premature discontinuation is a common pitfall 2
• Prokinetic agents (metoclopramide 10 mg three times daily) may be added for inadequate response to PPIs alone 2
• Full acid suppression may require combination therapy with twice-daily PPIs plus nocturnal H₂-receptor antagonists 2
• Failure to consider GERD is a frequent cause of therapeutic failure 2

Step 4: Nonasthmatic Eosinophilic Bronchitis (NAEB)

NAEB accounts for 6.4–17.2% of cases and is characterized by eosinophilic airway inflammation without airway hyperresponsiveness or variable airflow obstruction. 2, 3

• Inhaled corticosteroids are effective in reducing cough severity in NAEB 2
• Diagnosis requires sputum eosinophil analysis when available, as spirometry and methacholine challenge are normal 2

Critical Management Principle: Multiple Simultaneous Causes

Up to 67% of patients have multiple simultaneous etiologies, so you must retain partially effective therapies and employ additive treatment strategies rather than abandoning one approach for another. 2, 3

• Sequential and additive therapy is essential—do not discontinue a partially effective treatment when adding the next intervention 4
• Formal quantification of treatment response using validated instruments is required at each step 1, 2, 4
• Schedule follow-up within 4–6 weeks after initial evaluation to reassess response and adjust treatment 2, 4

Advanced Investigation for Refractory Cases

When targeted work-up is normal and empiric treatments have failed, proceed to specialized testing before labeling the cough as idiopathic. 1, 2

• High-resolution computed tomography is indicated when other investigations are normal and empirical treatments have failed 1, 2
• Bronchoscopy is reserved for suspected foreign-body aspiration 1, 2
• Referral to a specialized cough clinic is warranted when the condition remains undiagnosed after systematic evaluation of UACS, asthma, GERD, and NAEB 2, 4

Management of Refractory Chronic Cough

A diagnosis of refractory or idiopathic cough should be made only after comprehensive evaluation in a specialized cough clinic, and cough hypersensitivity syndrome should be considered as the underlying mechanism. 2, 3, 6

• Gabapentin trial starting at 300 mg once daily, escalating to maximum 1,800 mg daily in divided doses, may be effective in refractory chronic cough 3
• Multimodality speech pathology therapy is an alternative approach for refractory chronic cough 3

Common Pitfalls to Avoid

• Assuming a single etiology when up to 67% of patients have multiple simultaneous causes requiring combination therapy 2, 3
• Using acid suppression alone for GERD-related cough without comprehensive lifestyle modifications and adequate duration (minimum 3 months) 2, 3
• Failing to discontinue ACE inhibitors before pursuing extensive work-up 2, 3
• Abandoning partially effective therapies instead of adding sequential treatments 2, 4
• Premature referral or labeling as idiopathic before systematically addressing all four major causes 2, 4
• Not using validated cough severity tools to objectively assess treatment response 1, 2, 3, 4