Antibiotic Selection for Acute Bronchitis with Penicillin Allergy
Do not prescribe antibiotics for acute bronchitis, regardless of penicillin allergy status, because 89–95% of cases are viral and antibiotics provide no meaningful clinical benefit while causing significant harm. 1, 2
Why Antibiotics Are Not Indicated
Respiratory viruses cause 89–95% of acute bronchitis episodes in otherwise healthy adults, making all antibiotics—including alternatives to penicillin—completely ineffective against the underlying cause 1, 2
Antibiotic therapy shortens cough by only ~0.5 days (approximately 12 hours) while significantly increasing adverse events (RR 1.20; 95% CI 1.05–1.36), including diarrhea, rash, yeast infections, and rare anaphylaxis 1, 3, 4
Multiple high-quality meta-analyses demonstrate no significant difference in overall clinical improvement between antibiotics and placebo (RR 1.07; 95% CI 0.99–1.15) 1
The FDA removed uncomplicated acute bronchitis from approved antimicrobial indications in 1998 due to lack of efficacy 2, 5
Common Diagnostic Pitfalls That Lead to Inappropriate Prescribing
Purulent (green/yellow) sputum occurs in 89–95% of viral bronchitis and does not indicate bacterial infection—it reflects inflammatory cells, not bacteria 1, 2, 6
Cough duration is not a marker of bacterial infection—viral bronchitis cough typically lasts 10–14 days and may persist up to 3 weeks without treatment 1, 2, 5
Early fever (first 1–3 days) is consistent with viral bronchitis—only fever persisting >3 days suggests possible bacterial superinfection or pneumonia 7
Exclude Pneumonia Before Diagnosing Bronchitis
Before labeling a case as acute bronchitis, assess for pneumonia by checking all of the following 1, 2, 5:
- Heart rate >100 beats/min
- Respiratory rate >24 breaths/min
- Oral temperature >38°C
- Abnormal chest examination (rales, egophony, tactile fremitus)
If any one of these is present, obtain a chest radiograph to rule out pneumonia, which requires different management 1, 2, 7
The Single Exception: Pertussis (Whooping Cough)
If pertussis is confirmed or strongly suspected (paroxysmal cough, post-tussive vomiting, inspiratory "whoop," cough >2 weeks), prescribe a macrolide antibiotic (azithromycin or erythromycin) immediately 1, 2, 7, 5
Isolate the patient for 5 days from treatment start; early macrolide therapy reduces coughing paroxysms and limits disease transmission 1, 7
Macrolides are safe in penicillin allergy and are the treatment of choice for pertussis 1, 7
Appropriate Management of Uncomplicated Acute Bronchitis
Patient Education (Most Important)
Inform patients that cough typically lasts 10–14 days and may persist up to 3 weeks, even without antibiotics 1, 2, 7, 5
Explain that antibiotics do not shorten the illness and expose them to adverse effects while promoting antibiotic resistance 1, 2, 8
Physician-patient communication has a greater impact on patient satisfaction than whether an antibiotic is prescribed 1, 5
Symptomatic Relief
Codeine or dextromethorphan for bothersome dry cough, especially if it disrupts sleep—provides modest relief 1, 7
Short-acting β₂-agonists (e.g., albuterol) only for patients with wheezing accompanying the cough 1, 7, 6
Environmental measures: remove irritants (dust, allergens) and use humidified air 1
Medications to Avoid
- Do not prescribe expectorants, mucolytics, antihistamines, inhaled or oral corticosteroids, or NSAIDs at anti-inflammatory doses—no consistent benefit demonstrated 1
When to Reassess (Red-Flag Criteria)
Advise patients to return if 1, 7:
- Fever persists >3 days (suggests possible bacterial superinfection or pneumonia)
- Cough persists >3 weeks (consider asthma, COPD, pertussis, GERD)
- Symptoms worsen rather than gradually improve
Special Population: High-Risk Patients with Comorbidities
If the patient has significant comorbidities (age >75 years with cardiac failure, insulin-dependent diabetes, serious neurological disorders, immunosuppression, or known COPD), different management may be required 7:
For COPD Exacerbations (Not Simple Bronchitis)
Antibiotics are indicated when increased sputum purulence is present plus either increased dyspnea or increased sputum volume 2
Penicillin-allergy alternatives for COPD exacerbations: 2, 7
- Doxycycline 100 mg twice daily for 5 days (first-line alternative)
- Macrolide (azithromycin or clarithromycin) for 5 days
- Respiratory fluoroquinolone (levofloxacin) for severe cases
These recommendations apply only to COPD exacerbations, not uncomplicated acute bronchitis 2
Summary Algorithm
- Assess vital signs and lung exam to exclude pneumonia 1, 2, 5
- If pneumonia is excluded and the patient is otherwise healthy: Do not prescribe antibiotics 1, 2, 5
- If pertussis is suspected: Prescribe macrolide immediately 1, 2, 7
- If the patient has COPD with exacerbation criteria: Consider doxycycline or macrolide 2, 7
- Provide education on expected 10–14 day cough duration and offer symptomatic treatment only 1, 2, 7