What are the diagnostic criteria and management for the common cold, acute bronchitis, post‑infectious cough, and post‑nasal drip in an otherwise healthy adult?

Diagnostic Criteria and Management of Common Cold, Acute Bronchitis, Post-Infectious Cough, and Post-Nasal Drip

Common Cold

Diagnostic Criteria

The common cold is diagnosed clinically by acute nasal symptoms (rhinorrhea, nasal obstruction, sneezing) with or without fever, throat irritation, hoarseness, and cough, lasting up to 3 weeks. 1

• Hallmark symptoms are nasal stuffiness and discharge, sneezing, sore throat, and cough 1
• May include constitutional symptoms such as fever, muscle aches, and fatigue 1
• Cough prevalence reaches 83% within the first 2 days of illness 1
• No chest radiograph infiltrate (rules out pneumonia) 1

Management

For adults with common cold, first-generation antihistamine/decongestant combinations or naproxen are strongly recommended for symptomatic relief. 1

• Antibiotics have no role and should not be prescribed 1
• Antitussives may provide short-term symptomatic relief of cough 1
• Expected duration is up to 3 weeks; patient education about self-limited nature is essential 2

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Acute Bronchitis

Diagnostic Criteria

Acute bronchitis is diagnosed by cough with or without sputum production lasting up to 3 weeks, with normal chest radiograph findings, after ruling out common cold, asthma exacerbation, and chronic bronchitis exacerbation. 1

• Critical pitfall: Acute bronchitis is frequently overdiagnosed; the common cold must be ruled out first 1
• Distinguish from common cold by absence of predominant nasal symptoms 1
• Rule out asthma (30-65% of suspected acute bronchitis cases are actually asthma) 1
• Patients with ≥2 similar episodes in past 5 years have 65% probability of mild asthma 1
• No infiltrate on chest radiograph (excludes pneumonia) 1

Management

Antibiotics should not be routinely prescribed for acute bronchitis, as the cause is viral and antibiotics provide minimal benefit (0.5 days reduction in cough duration) while exposing patients to adverse effects. 1, 2

• No routine prescription of antibiotics, antivirals, antitussives, inhaled beta-agonists, inhaled anticholinergics, inhaled corticosteroids, oral corticosteroids, or NSAIDs 1
• Symptom relief and patient education about expected 2-3 week duration are recommended 2
• If worsens, reassess for bacterial complications (bacterial sinusitis) or alternative diagnoses 1
• Exception: If pertussis suspected (paroxysmal cough, post-tussive vomiting, inspiratory whoop), treat with macrolide antibiotics early in course 1

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Post-Infectious Cough

Diagnostic Criteria

Post-infectious cough is diagnosed when cough persists for 3-8 weeks following an acute respiratory infection, with normal chest radiograph findings. 1

• Subacute cough category (3-8 weeks duration) 1
• Follows symptoms of upper respiratory tract infection 1
• Normal chest radiograph rules out pneumonia 1
• If cough persists >8 weeks, consider other diagnoses (upper airway cough syndrome, asthma, GERD) 1

Pathogenesis

Multiple factors contribute: postviral airway inflammation, bronchial hyperresponsiveness, mucus hypersecretion, impaired mucociliary clearance, upper airway cough syndrome, asthma, and GERD 1

Management

For post-infectious cough not due to bacterial sinusitis or early pertussis, antibiotics have no role; consider inhaled ipratropium as first-line therapy. 1

Treatment algorithm:

1. First-line: Inhaled ipratropium (fair evidence for attenuation of cough) 1

2. If cough persists and affects quality of life: Add inhaled corticosteroids 1

3. For severe paroxysms: Consider prednisone 30-40 mg daily for short, finite period after ruling out UACS, asthma, and GERD 1

4. If other measures fail: Central-acting antitussives (codeine or dextromethorphan) 1

5. Assess for contributing factors: Treat bacterial sinusitis if present; consider UACS or GERD as complications of vigorous coughing 1

Pertussis-specific management:

• Suspect if cough ≥2 weeks with paroxysms, post-tussive vomiting, or inspiratory whoop 1
• Macrolide antibiotics (erythromycin, clarithromycin, azithromycin) effective only when given early (first few weeks) 1
• Isolate patient for 5 days from treatment start 1
• Long-acting beta-agonists, antihistamines, corticosteroids, and pertussis immunoglobulin have no benefit 1

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Post-Nasal Drip (Upper Airway Cough Syndrome)

Diagnostic Criteria

Post-nasal drip, now termed Upper Airway Cough Syndrome (UACS), is a clinical diagnosis of exclusion characterized by sensation of secretions dripping down the throat, throat clearing, and cough, with or without associated rhinitis or chronic rhinosinusitis. 1, 3

• Clinical diagnosis with no objective testing or pathognomonic findings 3
• Symptoms include throat clearing, sensation of postnasal drip, and cough 1, 4
• May present with or without rhinitis/rhinosinusitis 3
• Endoscopic finding: "reddish curtain sign" on posterior pharyngeal wall behind palatopharyngeal arch (90% sensitivity) 5
• Can be caused by persistent inflammation of nose and paranasal sinuses following respiratory infection 1

Management

Dual therapy with first-generation H1-receptor antihistamines and decongestants is the recommended treatment; diagnosis is confirmed when symptoms resolve with therapy. 3

• First-generation antihistamine/decongestant combination is primary treatment 1, 3
• Diagnosis confirmed by therapeutic response (symptom resolution) 3
• If associated with bacterial sinusitis, antibiotics are indicated 1
• UACS accounts for one of the top three causes of chronic cough (along with asthma and GERD) 3

Common pitfall: The traditional pathophysiology that inflamed nasal secretions directly irritate the airway may not fully explain UACS-related cough; airway sensory hypersensitivity may play a role 6