Acute Bronchitis
Self-limited inflammation of the large airways, almost always viral.
Also known as: acute bronchitis, viral bronchitis, chest cold
Overview
Self-limited inflammation of the trachea and large bronchi, predominantly viral in etiology, characterized by acute cough lasting up to 3 weeks, with or without sputum production, in patients without chronic lung disease.
Epidemiology
One of the most common reasons for ambulatory visits in the US (~5% of adults annually). Peak incidence in fall and winter. Antibiotic overprescription is a major stewardship concern — ~70% of cases historically received antibiotics despite minimal benefit.
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Risk factors
- Recent viral upper respiratory infection
- Smoking, secondhand smoke
- Environmental irritants (cold air, allergens, fumes)
- Air pollution
- Crowded living conditions, daycare exposure
Pathophysiology
Viral infection of bronchial epithelium → mucosal inflammation, edema, hypersecretion of mucus, bronchial hyperresponsiveness, and sloughing of cells → cough that can persist for 1-3 weeks after acute infection resolves due to lingering airway inflammation. Common pathogens: influenza A and B, RSV, rhinovirus, coronavirus (including SARS-CoV-2), adenovirus, parainfluenza, metapneumovirus. Bacterial causes (<10%): Bordetella pertussis, Mycoplasma pneumoniae, Chlamydophila pneumoniae.
Clinical presentation
Symptoms
- Cough — initially dry, often becoming productive of clear or purulent sputum (PURULENT SPUTUM ALONE DOES NOT INDICATE BACTERIAL INFECTION)
- Mild dyspnea, wheeze, chest discomfort with coughing
- Often preceded by URI symptoms: rhinorrhea, sore throat, mild fever (low-grade)
- Cough typically resolves within 1-3 weeks; postinfectious cough can last 6-8 weeks
Signs / physical exam
- Generally normal exam; possible rhonchi/wheeze that clear with coughing
- Low-grade fever or afebrile
- Normal SpO2 and respiratory rate
- Absence of focal consolidation, dullness, egophony (would suggest pneumonia)
Differential diagnosis
- Community-acquired pneumonia — Fever >38°C, tachycardia, tachypnea, focal exam findings, abnormal CXR with infiltrate
- Influenza — Abrupt fevers, myalgia, headache, seasonal occurrence; positive rapid antigen/PCR; tamiflu within 48 h
- COVID-19 — Anosmia, ageusia, contacts, positive PCR/antigen; can have prolonged cough
- Pertussis — Paroxysmal coughing fits with inspiratory whoop, post-tussive emesis, >2 weeks of cough; nasopharyngeal PCR
- Asthma exacerbation — Wheeze, prior asthma history, reversibility with bronchodilator
- GERD-related cough — Cough worse supine, postprandial, regurgitation; responds to PPI trial
- Postnasal drip / upper airway cough syndrome — Throat clearing, drip sensation, allergic rhinitis; responds to antihistamines/nasal steroids
- ACE inhibitor cough — Dry cough developing after ACEi start; resolves on discontinuation (may take 4 weeks)
Diagnostic workup
Labs
- Generally NONE needed in immunocompetent ambulatory patients with classic presentation
- Procalcitonin and CRP not routinely indicated but can support antibiotic stewardship
- Targeted viral testing: influenza (if antivirals considered or seasonal/outbreak), SARS-CoV-2 (per current public health guidance), RSV in select populations
- Pertussis PCR (nasopharyngeal) if classic paroxysmal cough with whoop or exposure
Imaging
- Chest radiograph NOT routinely needed — obtain if any of: HR >100, RR >24, T >38°C, focal exam findings (consolidation, rales), age >65, or immunocompromise — to exclude pneumonia
- CDC/IDSA suggest CXR to differentiate from CAP when clinical picture is uncertain
Diagnostic algorithm
| Feature | Acute Bronchitis | Pneumonia |
|---|---|---|
| Vitals | Often normal | Fever >38°C, HR >100, RR >24 |
| Exam | Diffuse rhonchi/wheeze; no consolidation | Focal crackles, egophony, dullness |
| CXR | Normal — usually not needed | Lobar or interstitial infiltrate |
| Treatment | Symptomatic only | Antibiotic therapy |
| Course | Resolves in 1-3 weeks | Improves with appropriate antibiotics |
Treatment
First-line
- Symptomatic and supportive care — antibiotics generally NOT indicated (high-value care)
- Hydration, rest
- Antitussives (dextromethorphan, benzonatate) for bothersome cough (modest evidence)
- Honey 1-2 tsp (for adults and children ≥1 year) — evidence-based cough relief, particularly nocturnal
- Throat lozenges, humidified air
- Inhaled short-acting beta-agonist (albuterol) reasonable if wheeze or bronchospasm; not for all comers
- NSAIDs or acetaminophen for fever or myalgia
- Influenza-positive: oseltamivir 75 mg BID × 5 days if within 48 h of onset or high-risk patient
Second-line / adjunct
- Antibiotics ONLY for documented or strongly suspected bacterial cause:
- Pertussis (high public health priority): macrolide — azithromycin 500 mg day 1 then 250 mg × 4 days OR clarithromycin; primary benefit is reduced transmission
- Mycoplasma or Chlamydophila (uncommon in true acute bronchitis): macrolide or doxycycline
- Patient education on expected duration (cough up to 3 weeks; postinfectious up to 6-8 weeks) to reduce antibiotic-seeking
- Re-evaluate if symptoms persist >3 weeks or worsen — consider pertussis, postnasal drip, asthma, GERD, ACEi cough, or alternative diagnosis
Complications
- Postinfectious cough (up to 6-8 weeks)
- Bronchial hyperreactivity / transient asthma-like symptoms
- Superimposed bacterial pneumonia (uncommon)
- Exacerbation of underlying COPD/asthma if unrecognized chronic disease
- Pertussis sequelae in vulnerable contacts (especially infants)
PANCE pearls
- Purulent (yellow/green) sputum does NOT indicate bacterial infection in acute bronchitis — color reflects neutrophilic inflammation, not pathogen.
- Routine antibiotic use does not shorten illness; ACP/CDC have campaigned for stewardship in this setting.
- Obtain CXR if HR >100, RR >24, T >38°C, age >65, or focal exam to exclude pneumonia.
- Persistent cough >3 weeks should prompt evaluation for pertussis, asthma, postnasal drip, GERD, or ACEi cough.
- Honey is the only widely accepted symptomatic intervention with evidence in both adults and children ≥1 year (botulism risk under 1).
References
- ACP/CDC 2016 — Appropriate Antibiotic Use for Acute Respiratory Tract Infection in Adults (Harris et al., Ann Intern Med 2016)
- CHEST 2006 — Diagnosis and Management of Cough Executive Summary: ACCP Evidence-Based Clinical Practice Guidelines (Irwin et al., Chest 2006)
- Cochrane Bronchitis — Antibiotics for Acute Bronchitis (Smith et al., Cochrane Database Syst Rev 2017)
- CDC Pertussis — Recommended Antimicrobial Agents for the Treatment and Postexposure Prophylaxis of Pertussis (Tiwari et al., MMWR 2005)
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