(See also: Cough, Barking; Cough, Productive)

A nonproductive cough—also referred to as a dry cough—is a forceful expulsion of air from the lungs without significant expectoration of sputum or mucus. Although a small amount of clear or mucoid sputum may occasionally be produced, the hallmark is the absence of effective airway clearance. It is one of the most frequently reported symptoms in patients with respiratory or systemic illnesses, and it warrants a thorough clinical assessment due to its broad differential diagnosis.

Clinical significance

Coughing is primarily a protective reflex that helps clear the airways of irritants, secretions, or foreign bodies. However, a nonproductive cough is often ineffective in clearing secretions and may cause iatrogenic harm. In some cases, vigorous coughing can result in complications such as:

• Airway collapse (especially in patients with preexisting airway malacia),

• Rupture of alveoli or subpleural blebs (predisposing to pneumothorax),

• Post-tussive syncope,

• Rib fractures (especially in elderly or osteoporotic individuals),

• Increased intracranial, intraocular, or intra-abdominal pressure (of concern in conditions like glaucoma, hernia, or aneurysms).

Importantly, the evolution from a dry to a productive cough often signals progression to a lower respiratory tract infection (e.g., bronchitis or pneumonia), which should be promptly evaluated and managed.

Pathophysiology of the cough reflex

The cough reflex involves a complex neurophysiologic mechanism:

1. Stimulation of cough receptors, located in the larynx, trachea, bronchi, pleura, pericardium, diaphragm, external auditory canals, esophagus, and gastrointestinal tract.

2. Afferent signals are transmitted via the vagus (CN X) and glossopharyngeal (CN IX) nerves to the cough center in the medulla oblongata.

3. A coordinated motor response follows:

   • Deep inspiration

   • Closure of the glottis

   • Contraction of abdominal and intercostal muscles

   • Sudden opening of the glottis, resulting in explosive air expulsion

External stimuli—including mechanical, chemical, thermal, or inflammatory irritants—can trigger this cascade. Psychogenic and voluntary triggers also exist and are seen in conditions such as habit cough syndrome or somatic cough disorder.

Etiology of nonproductive Cough

A comprehensive differential diagnosis includes infectious, inflammatory, neoplastic, cardiovascular, gastrointestinal, allergic, and drug-induced causes. Some notable etiologies are:

Respiratory Causes

• Asthma: Early attacks often present with a dry cough, later progressing to wheezy episodes and mucus production.

• Atypical pneumonia: (e.g., Mycoplasma pneumoniae, Chlamydophila pneumoniae) may present primarily with a dry cough.

• Chronic bronchitis: Begins with a dry, hacking cough, often becoming productive over time.

• Bronchogenic carcinoma: Chronic dry cough may be the first symptom in lung cancer; must be ruled out in smokers or those with hemoptysis.

• Interstitial lung disease (ILD): Cough is typically dry and persistent.

• Tuberculosis: Chronic dry cough is often accompanied by constitutional symptoms.

Cardiovascular Causes

• Left-sided heart failure: Can cause pulmonary congestion and dry cough, particularly when supine.

• Thoracic aortic aneurysm: May compress the trachea or recurrent laryngeal nerve, causing dry, brassy cough and hoarseness.

Gastrointestinal Causes

• GERD (Gastroesophageal Reflux Disease): Microaspiration and laryngopharyngeal reflux can induce a chronic dry cough, especially nocturnally.

• Esophageal motility disorders: Such as achalasia or diverticula, may lead to recurrent aspiration and chronic cough.

  
  

Infectious Diseases:

• Avian influenza (H5N1), COVID-19, RSV: May cause a persistent dry cough with systemic symptoms.

• Inhalation anthrax: Initial flulike symptoms include dry cough; rapid deterioration may follow.

  
  

Drug-Induced:

• ACE inhibitors (e.g., enalapril, lisinopril): Up to 20% of patients develop a persistent, nonproductive cough.

• Beta-blockers (in reactive airway patients): May provoke cough or bronchospasm.

  
  

Environmental/Allergic Causes

• Postnasal drip syndrome (upper airway cough syndrome): Often presents with a dry cough due to throat clearing.

• Allergic rhinitis or irritant exposure (smoke, dust, pollution): Can stimulate cough receptors.

Other:

• Foreign body aspiration (especially in children): Sudden onset dry cough, choking episodes, and unilateral decreased breath sounds.

• Psychogenic (habit cough): Often seen in adolescents and characterized by a honking cough with absence during sleep.

Medical causes of nonreproductive cough

Here is the detailed information of the causes with additional "Special consideration" column for key clinical notes, risk factors, or unique diagnostic points.

Clinical evaluation

History taking

• Onset: Sudden or insidious?

• Duration: Acute (<3 weeks), subacute (3–8 weeks), or chronic (>8 weeks)?

• Character: Dry, brassy, hacking, honking?

• Triggers: Position (e.g., supine in CHF or GERD), exertion, cold air, allergens?

• Associated symptoms: Fever, weight loss, night sweats, dyspnea, wheezing, hemoptysis?

• Smoking history: Quantify in pack-years.

• Medication review: Focus on recent initiation or dose changes.

• Environmental exposure: Chemicals, occupational irritants, secondhand smoke.

• TB risk factors: Country of origin, previous TB exposure, immunocompromised status.

Physical examination

• General: Cachexia, cyanosis, digital clubbing, use of accessory muscles, agitation or lethargy.

• ENT: Inspect nasal mucosa, oropharynx, and ears (foreign body in children).

• Neck: Jugular venous distension, tracheal deviation, cervical lymphadenopathy.

• Chest:

  • Inspection: Retractions, barrel chest, respiratory pattern.

  • Palpation: Tactile fremitus.

  • Percussion: Dullness (effusion, consolidation), hyperresonance (emphysema, pneumothorax).

  • Auscultation: Wheezes, rhonchi, crackles, decreased or absent breath sounds.

• Cardiovascular: Murmurs, gallops (e.g., S3 in heart failure).

• Abdomen: Hepatomegaly (congestive hepatopathy), signs of ascites, abdominal masses.

Special considerations

Pediatric patients

• Assess for foreign body aspiration, especially in toddlers.

• Congenital anomalies (e.g., tracheomalacia) or asthma must be considered.

Geriatric patients

Always ask elderly patients about nonproductive coughing because it may be an indication of serious acute or chronic illness.

Cultural sensitivity

Stigma around TB may lead to delayed disclosure. Approach patients from high-prevalence areas (e.g., sub-Saharan Africa, Southeast Asia) with sensitivity and appropriate screening questions.

Management overview

Management depends on the underlying etiology:

• Symptomatic relief: Antitussives (e.g., dextromethorphan, benzonatate) may be considered in selected patients with dry cough disrupting sleep or causing discomfort. Avoid in productive cough unless indicated.

• Targeted treatment: Address primary cause (e.g., PPI for GERD, ICS/LABA for asthma, antibiotic for pneumonia).

• Discontinue offending agents: Especially ACE inhibitors.

• Smoking cessation: Vital for chronic cough resolution and long-term lung health.

References

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16. Let me know if you need references for a specific condition or more recent journal articles.