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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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)
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
Bedside differentiation of acute bronchitis from community-acquired pneumonia.
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
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