Acute bronchitis is a lower respiratory tract infection (LRTI) characterized by inflammation of the bronchi. It often follows an upper respiratory tract infection (URTI) and, in more than 90% of cases, the cause is viral. Acute bronchitis may manifest with cough, runny nose, headache, and malaise. The cough may persist for 2–3 weeks and is usually self-limiting; it is often productive and associated with chest pain. The diagnosis is made on the basis of clinical symptoms and auscultation findings; further diagnostic testing is not routinely necessary. Important differential diagnoses to consider include asthma, acute exacerbation of COPD, and pneumonia. Management of acute bronchitis consists of adequate hydration and symptomatic relief. Treatment with antibiotics is not generally indicated. While chronic bronchitis also involves inflammation of the bronchi, its clinical picture and management are very different (see “COPD”).
- Viral (> 90% of cases)
The etiology of acute bronchitis is viral in > 90% of cases!
Signs and symptoms 
- Symptoms of preceding or simultaneous URTI
- Runny nose and sore throat
- Chest pain
- Mild dyspnea
- Fever (uncommon after first few days)
- Vital signs are usually normal. 
- Auscultation findings 
- Acute bronchitis is a clinical diagnosis based on typical clinical features and auscultation findings
- Diagnostic studies are usually only required to: 
Routine laboratory and imaging studies 
- CBC: may show mild leukocytosis
- Indication: to evaluate for pneumonia in patients with abnormal examination findings or atypical clinical presentation 
- Findings: often normal or nonspecific, e.g., peribronchial thickening 
Further diagnostic testing 
Consider targeted testing for alternate diagnoses or complications in patients with the following:
- High fevers: Consider a diagnosis of pneumonia or influenza (see “Diagnostics” in “Influenza”).
- Prominent coughing fits: Consider pertussis testing. 
- Worsening symptoms or cough lasting > 3 weeks: Consider adding sputum culture, spirometry, or other laboratory studies (e.g., CRP) depending on clinical suspicion. 
- Recurrent episodes of bronchitis: Consider diagnostic testing for asthma or COPD.
In otherwise healthy patients with typical clinical findings and normal vital signs, acute bronchitis does not require diagnostic testing. 
- For cough persisting < 8 weeks, see “Differential diagnosis of acute cough.”
- For cough persisting ≥ 8 weeks, see “Differential diagnosis of chronic cough.”
The differential diagnoses listed here are not exhaustive.
Acute bronchitis is generally self-limiting. Treatment is focused on the relief of symptoms. 
- Supportive management
Symptomatic treatment 
- Analgesics: NSAIDs or acetaminophen 
- Other symptom relievers: not routinely recommended ; 
- See “Treatment” in “Cough” for more details on symptomatic treatment.
Antibiotic treatment 
- Generally not recommended
- Only consider antibiotics in patients with suspected bacterial complications or an alternate diagnosis (e.g., pneumonia, pertussis, acute exacerbation of COPD).
Treatment is focused on symptomatic management. Antibiotics, cough and cold medications, bronchodilators, and steroids have no proven efficacy in uncomplicated acute bronchitis.
- Respiratory failure
- Secondary bacterial infections (especially pneumonia)
Protracted bacterial bronchitis 
- Chronic bacterial infection that causes a productive cough
Clinical diagnosis requires all of the following:
- Daily cough for > 4 weeks
- Resolution within 2–4 weeks of antibiotic treatment
- Absence of alternate diagnosis
We list the most important complications. The selection is not exhaustive.
- Generally self-limiting
- Risk factors for complications: advanced age, immunocompromise, preexisting lung conditions