Why do keep on coughing

Overview

Coughing is a protective reflex that helps clear the airways of irritants, mucus, and foreign particles. The history of cough research dates back to ancient civilizations, with Hippocrates (460-370 BCE) describing cough as a symptom of various diseases. In modern medicine, cough classification has evolved significantly since the 1970s when Irwin and colleagues established systematic diagnostic approaches. Chronic cough, defined as lasting 8 weeks or longer in adults (4 weeks in children), affects approximately 10-20% of the global population. The economic impact is substantial, with chronic cough accounting for over 30 million physician visits annually in the United States alone. Research published in the journal Chest (2015) revealed that chronic cough patients experience significant quality of life impairment, with 53% reporting sleep disturbances and 43% experiencing urinary incontinence during coughing episodes.

How It Works

Coughing involves a complex neurological reflex arc that begins with stimulation of cough receptors located throughout the respiratory tract, particularly in the larynx, trachea, and bronchi. These receptors detect mechanical, chemical, or inflammatory stimuli and send signals via the vagus nerve to the cough center in the medulla oblongata of the brainstem. The reflex then triggers a coordinated sequence: first, a deep inhalation (taking in about 2.5 liters of air in adults), followed by closure of the glottis and contraction of expiratory muscles, creating intrathoracic pressure of up to 300 mmHg. Finally, the glottis opens suddenly, producing an explosive expiration with airflow velocities reaching 500 miles per hour. This mechanism efficiently clears airways but becomes problematic when persistent, often due to hypersensitivity of cough receptors, a condition called cough hypersensitivity syndrome that affects nerve pathways and inflammatory mediators like bradykinin and prostaglandins.

Why It Matters

Persistent coughing has significant real-world consequences beyond being a mere annoyance. Chronic cough is associated with multiple complications including rib fractures (occurring in up to 4% of severe cases), syncope (cough-induced fainting in 2-5% of patients), and urinary incontinence affecting 25-50% of women with chronic cough. The economic burden is substantial, with chronic cough costing the U.S. healthcare system approximately $1.2 billion annually in direct medical expenses. Socially, chronic cough causes embarrassment and isolation, with studies showing 75% of patients avoid social situations. Diagnosing the underlying cause is crucial since 90% of chronic cough cases can be successfully treated when properly identified, significantly improving quality of life and reducing healthcare utilization.