How do I distinguish acute from chronic bronchitis and what is the initial management for a patient presenting with a new cough, sputum production, and low‑grade fever?

Distinguishing Acute from Chronic Bronchitis and Initial Management

For a patient presenting with new cough, sputum production, and low-grade fever, diagnose acute bronchitis only after ruling out pneumonia (via vital signs and chest exam), common cold, asthma, and COPD exacerbation—then provide supportive care without antibiotics, as this is a self-limited viral illness lasting up to 3 weeks. 1

Key Distinguishing Features

Acute Bronchitis

• Duration: Cough with or without sputum production lasting up to 3 weeks (occasionally up to 6 weeks for post-infectious cough) 1, 2
• Presentation: Predominantly lower respiratory symptoms with cough as the primary complaint, may have constitutional symptoms (fever, myalgias, fatigue) 1, 3
• Etiology: Viral in >90% of cases; self-limited illness in otherwise healthy patients 1, 4
• Pattern: Isolated, acute event without recurrent episodes 3

Chronic Bronchitis

• Duration: Productive cough on most days of the month for 3 months over 2 consecutive years 5
• Pathophysiology: Irreversible reduction in maximal airflow velocity, often with underlying COPD 5
• Pattern: Persistent baseline symptoms with acute exacerbations characterized by increased dyspnea, sputum volume, and sputum purulence 1, 5
• Risk factors: Smoking history, underlying lung disease, recurrent infections 1, 6

Critical Diagnostic Algorithm for New Presentation

Step 1: Rule Out Pneumonia First

Check vital signs and perform focused chest examination 3:

• Heart rate >100 bpm
• Respiratory rate >24 breaths/min
• Temperature >38°C (100.4°F)
• Focal chest findings (consolidation, egophony, fremitus)

If ANY of these are present: Obtain chest X-ray immediately to exclude pneumonia 3, 7

Step 2: Differentiate from Common Cold

Common cold features 1, 3:

• Predominant upper respiratory symptoms: nasal stuffiness/discharge, sneezing, sore throat
• Cough is secondary (though present in up to 83% within first 2 days)
• Associated with throat clearing and postnasal drip sensation

Acute bronchitis features 1, 2:

• Cough is the predominant manifestation
• Lower respiratory tract symptoms dominate
• May start as dry cough, then become productive

Step 3: Rule Out Asthma Masquerading as Bronchitis

This is a critical pitfall—approximately one-third of patients diagnosed with acute bronchitis actually have asthma 1, 2

Red flags for asthma 3:

• History of ≥2 similar episodes in past 5 years (65% have mild asthma) 1
• Wheezing as prominent feature
• Prolonged expiration on examination
• Symptoms triggered by allergens, cold air, or exercise
• Cough worsening at night
• Symptoms persisting beyond 3 weeks

Consider spirometry if available when patient has wheezing, prolonged expiration, smoking history, or allergy symptoms 3

Step 4: Exclude COPD Exacerbation

Only relevant if patient has known chronic lung disease or risk factors 1:

• History of chronic productive cough
• Smoking history
• Baseline dyspnea
• Known airflow obstruction

Initial Management for Acute Bronchitis

What NOT to Do

Do not prescribe antibiotics 1, 4, 8:

• Antibiotics reduce cough duration by only 0.5 days while exposing patients to adverse effects (allergic reactions, nausea, C. difficile infection) 8, 7
• Viruses cause >90% of cases 1, 4
• Sputum color (yellow/purulent) does not indicate bacterial infection—it reflects inflammatory cells from viral infection 4

Recommended Management

Patient education is paramount 8, 7:

• Explain expected cough duration of 2-3 weeks (up to 6 weeks for some) 2, 8
• Describe condition as "chest cold" rather than "bronchitis" to reduce antibiotic expectations 8, 7

Supportive care only 1, 8:

• Symptom relief measures
• Adequate hydration
• Avoidance of respiratory irritants

Evidence does NOT support 8:

• Antitussives (minimal benefit)
• Honey
• Antihistamines
• Oral or inhaled corticosteroids
• Bronchodilators (unless underlying asthma/COPD)

When to Reconsider Diagnosis

If cough persists >3 weeks, evaluate for 1, 4:

• Post-infectious cough
• Asthma
• Upper airway cough syndrome (postnasal drip)
• Gastroesophageal reflux disease
• Pertussis (especially if paroxysmal cough, post-tussive emesis, or known exposure) 7
• Bronchiectasis

Common Pitfalls to Avoid

1. Misdiagnosing asthma as acute bronchitis: Prospectively follow patients to determine if this is truly an isolated event or the first presentation of chronic disease 1, 2

2. Prescribing antibiotics based on sputum color: Yellow or green sputum does not indicate bacterial infection 4

3. Failing to check vital signs: Missing pneumonia because you didn't measure respiratory rate or temperature 3, 7

4. Not educating about expected duration: Patients seek care expecting quick resolution; explaining the 2-3 week natural course reduces dissatisfaction and antibiotic demands 8, 7