What are the common causes of cough‑induced bronchospasm in patients with asthma or chronic obstructive pulmonary disease?

Cough-Induced Bronchospasm: Common Causes

The most common causes of cough-induced bronchospasm are drug-induced bronchospasm (particularly from beta-blockers, aspirin, and NSAIDs), asthma with airway hyperresponsiveness, and nonasthmatic eosinophilic bronchitis—all of which require identification and targeted treatment to prevent morbidity from progressive airway dysfunction. 1

Drug-Induced Bronchospasm with Cough

Drug-induced causes must be evaluated first as they are reversible and frequently overlooked. 1

• Beta-blockers cause bronchospasm with or without cough through direct airway smooth muscle effects, and should be discontinued when bronchospasm develops 1
• Aspirin and NSAIDs trigger bronchospasm through non-IgE mediated mechanisms, particularly in patients with underlying airway hyperresponsiveness 1
• ACE inhibitors cause chronic dry cough that can trigger bronchospasm in susceptible patients, though the mechanism differs from direct bronchospasm 1
• Antibiotics including amphotericin, erythromycin, sulfonamides, and aminoglycosides can cause bronchospasm 1
• Inhaled medications themselves may paradoxically cause bronchospasm and cough 1

A therapeutic trial of withdrawing the suspected drug should be considered, as this often resolves both cough and bronchospasm (Grade B recommendation) 1

Asthma and Cough-Variant Asthma

Asthma is the most common disease-related cause of cough-induced bronchospasm, accounting for approximately 25% of chronic cough cases. 2

• Variable airflow obstruction and airway hyperresponsiveness are cardinal features that distinguish asthma from other causes 2
• Cough-variant asthma presents with isolated cough without wheeze, but demonstrates the same airway hyperresponsiveness on testing 3, 2
• Eosinophilic airway inflammation drives both the cough reflex hypersensitivity and bronchospasm 1, 2
• Episodic nocturnal cough may be the only symptom between acute exacerbations 3
• Bronchospasm in asthma responds to inhaled corticosteroids and long-acting beta-agonists 4

The cough itself represents bronchial hyperresponsiveness rather than being a direct measure of asthma severity, so other etiologies must be considered even when asthma is present 3

Nonasthmatic Eosinophilic Bronchitis

Nonasthmatic eosinophilic bronchitis accounts for 10-30% of chronic cough cases and causes bronchospasm without the airway hyperresponsiveness seen in asthma. 1, 2

• Defined by chronic cough with sputum eosinophilia ≥3%, normal airway responsiveness (methacholine PC20 >16 mg/mL), and no variable airflow obstruction 1
• Responds excellently to inhaled corticosteroids, with improvement associated with reduction in airway eosinophilia 1, 2
• May be associated with occupational sensitizer exposure or common inhaled allergens 1
• Bronchospasm occurs along with dry cough despite normal spirometry and methacholine challenge 1

Sputum analysis for eosinophils is essential to diagnose this condition, as it cannot be distinguished from other causes by history alone 1

COPD and Chronic Bronchitis

In COPD patients, cough can trigger bronchospasm through airway irritation and heightened cough reflex sensitivity. 5, 6

• Cigarette smoking is the dominant risk factor, causing chronic inflammation that increases both cough and bronchospasm 1
• Occupational exposures to organic dusts (cotton, hemp, linen) contribute to approximately 15% of chronic bronchitis cases 7
• Increased sensitivity to capsaicin is common in COPD, reflecting altered cough reflex pathways 5
• Airway narrowing itself can induce coughing, creating a self-perpetuating cycle 5

Smoking cessation should always be encouraged, as 90% of patients will have resolution of sputum production after stopping 1

Pathophysiologic Mechanisms

Cough-induced bronchospasm occurs through multiple interconnected mechanisms:

• Cough hypersensitivity with augmented sensory nerve excitability affects upper-airway vagal sensory nerves 4
• Plastic changes in brainstem, spinal, or airway nerve excitability can enhance and perpetuate the cough reflex even after the initiating event resolves 6
• Eosinophilic inflammation increases both cough sensitivity and bronchospasm through shared inflammatory pathways 1, 2
• Bronchoconstriction itself triggers coughing, which then worsens bronchospasm in a vicious cycle 5, 4

Critical Diagnostic Approach

A systematic evaluation is essential to identify the specific cause:

1. Obtain detailed medication history focusing on beta-blockers, aspirin, NSAIDs, ACE inhibitors, and inhaled medications 1
2. Perform spirometry with bronchodilator testing to document variable airflow obstruction and reversibility 1
3. Measure methacholine responsiveness to distinguish asthma (positive) from nonasthmatic eosinophilic bronchitis (negative) 1
4. Analyze induced sputum for eosinophils (≥3% indicates eosinophilic bronchitis) 1
5. Assess for occupational or environmental exposures including tobacco smoke and organic dusts 1, 7

Common Pitfalls to Avoid

• Do not assume all cough with bronchospasm is asthma—nonasthmatic eosinophilic bronchitis requires different long-term management despite similar initial treatment 1
• Do not overlook drug-induced causes, as they are completely reversible with medication withdrawal 1
• Do not rely on clinical features alone—objective testing with spirometry, methacholine challenge, and sputum analysis is required for accurate diagnosis 1
• Do not ignore occupational exposures, as approximately 15% of chronic bronchitis is work-related and often missed 7
• Do not treat cough suppressants in productive cough, as they may impair secretion clearance and worsen outcomes 8