What is Chronic Cough?
 

Chronic cough is a cough lasting 8 weeks or longer in adults (or more than 4 weeks in children). 

Causes of Chronic "Coughing"
 

Upper Airway Cough Syndrome (UACS) / Post-Nasal Drip

• ​Inflammation of the nasal mucosa and sinuses leads to mucus dripping down the posterior pharynx, triggering upper airway cough receptors. Etiologies: Allergic rhinitis, non-allergic perennial rhinitis, vasomotor rhinitis, and chronic rhinosinusitis (with or without nasal polyps).

Cough-Variant Asthma

• A unique form of asthma where a chronic, dry cough is the sole clinical symptom, driven by bronchial hyperresponsiveness and airway inflammation (without classic expiratory wheezing).

Non-Asthmatic Eosinophilic Bronchitis

• Characterized by airway eosinophilia and chronic cough, but with normal spirometry and no bronchial hyperresponsiveness.​

Gastroesophageal Reflux Disease (GERD)

• Gastric acid and contents refluxing into the esophagus stimulate esophageal-tracheobronchial neural reflexes (micro-aspiration or vagal reflex arcs), triggering cough even in the absence of classic heartburn or dyspepsia.

Medication-Induced Cough

• ACE Inhibitors: Angiotensin-converting enzyme inhibitors (e.g., lisinopril, enalapril) block the breakdown of bradykinin and substance P, causing a persistent, dry, hacking cough in up to 20% of patients. This can manifest months after starting the drug and resolves weeks after discontinuation.

Chronic Bronchitis & Obstructive Lung Diseases

• COPD & Bronchiectasis: Productive chronic cough driven by airway remodeling, excessive mucus hypersecretion, chronic inflammation, or permanent, abnormal dilation of the bronchi (often associated with recurrent bacterial infections and purulent sputum).

Infectious & Post-Infectious States

• Pertussis (Whooping Cough): Bordetella pertussis infection causing a prolonged paroxysmal cough that can persist for months.

• Post-Infectious Cough: A transient, self-limiting cough persisting weeks after a resolved viral upper respiratory infection due to temporary mucosal hypersensitivity.

• Fungal & Mycobacterial Infections: Tuberculosis, non-tuberculous mycobacteria (NTM), or endemic fungal pathogens.

• Protracted Bacterial Bronchitis — An important cause of chronic wet cough lasting more than 4 weeks, particularly in children. It is caused by persistent bacterial infection of the airways and typically improves with an appropriate course of antibiotics. Recurrent or persistent cases may require further evaluation for an underlying airway or lung disorder.

Environmental & Occupational Exposures

• Cigarette Smoking: The leading cause of chronic productive cough ("smoker's cough") leading to chronic bronchitis.

• Inhalational Irritants: Occupational exposure to dust, chemical fumes, mold, or particulate matter which can cause pulmonary fibrosis.

Malignancy

• Particularly bronchogenic carcinoma
   

Diagnostics
​

• Clinical History & Physical Exam: Detailed smoking history, exact medication reconciliation (specifically checking for ACE inhibitors), description of sputum production, and identification of triggers (e.g., talking, cold air, lying down).

• Initial Imaging: Chest X-ray (CXR) as a mandatory first-line test to rule out malignancy, interstitial lung disease, bronchiectasis, or structural abnormalities.

• Pulmonary Function Testing (PFTs): Spirometry with bronchodilator responsiveness to evaluate for obstructive airway disease or cough-variant asthma. If spirometry is normal but CVA is suspected, methacholine inhalation challenge testing assesses bronchial hyperresponsiveness.

• Allergy & Airway Evaluation:

  • Assessing for nasal polyps or sinus disease (via physical exam or sinus CT).

  • Exhaled nitric oxide (FeNO) or induced sputum cytology to screen for eosinophilic airway inflammation.

• Gastrointestinal Evaluation: 24-hour pH monitoring or impedance testing if GERD-induced cough is suspected and empiric anti-reflux therapy fails.

Management 
 

Targeted Treatment Based on Etiology
 

• For Upper Airway Cough Syndrome: Intranasal corticosteroids, second-generation antihistamines, or nasal saline rinses.

• For Cough-Variant Asthma / NAEB: Inhaled corticosteroids (ICS), and possibly beta-agonists (LABA) or oral leukotriene receptor antagonists (e.g., montelukast).

• For GERD-Induced Cough: Proton pump inhibitors (PPIs), H2 blockers, and strict lifestyle modifications (dietary changes, elevating the head of the bed).

• For ACE Inhibitor-Induced Cough: Discontinuation of the ACE inhibitor and switching to an alternative class (such as an ARB).

Empiric & Symptom-Directed Therapies
 

• Multimodality Empiric Treatment: In complex cases where multiple triggers coexist, clinicians frequently treat UACS, CVA, and GERD concurrently.

• Neuromodulators: For refractory chronic cough (unexplained chronic cough or neurogenic cough hypersensitivity syndrome), low-dose neuromodulators such as gabapentin, pregabalin, or amitriptyline are utilized to dampen hypersensitized vagal cough receptors.

                                                          References & Guidelines
 

• American College of Chest Physicians (CHEST). Guidelines and Expert Panel Reports on the Diagnosis and Management of Chronic Cough.

• European Respiratory Society (ERS). Guidelines on the Diagnosis and Treatment of Chronic Cough in Adults and Children.

• American College of Chest Physicians (CHEST). Managing Chronic Cough as a Symptom in Children and Management Algorithms.

• American College of Chest Physicians (CHEST). Chronic Cough Due to Gastroesophageal Reflux in Adults: CHEST Guideline and Expert Panel Report.