Recommended Doses of Inhaled Bronchodilators for Acute Viral Bronchitis
β₂-agonist bronchodilators should NOT be routinely used in most patients with acute viral bronchitis, but in select adults with wheezing accompanying the cough, albuterol 2-4 inhalations (200-400 μg) every 4 hours may be useful. 1, 2
Primary Recommendation: Do Not Use Routinely
The American College of Chest Physicians explicitly recommends against routine use of β₂-agonist bronchodilators in most patients with acute viral bronchitis (Grade D recommendation). 3, 2
A Cochrane review of five trials in adults found no significant benefit in reducing daily cough scores or the number of patients still coughing after 7 days. 2
Adverse effects—including tremors, nervousness, and agitation—were more common in patients receiving β₂-agonists than placebo. 2
Acute viral bronchitis is caused by respiratory viruses in 89-95% of cases, making bronchodilators ineffective at addressing the underlying cause. 1
Exception: Patients with Wheezing
The presence of wheezing at the onset of illness identifies a subgroup that may benefit from bronchodilator therapy. 2, 4
Dosing Regimen for Adults with Wheezing:
Albuterol/salbutamol inhaler: 2-4 inhalations (200-400 μg) via metered-dose inhaler every 4 hours for mild episodes. 2
For moderately severe episodes: 400 μg (4 inhalations) every 4 hours. 2
The American College of Chest Physicians states that β₂-agonists may be useful in select adult patients with wheezing accompanying the cough (Grade C recommendation). 2, 4
Supporting Evidence from Clinical Trials
While guidelines recommend against routine use, two older randomized trials showed some benefit:
Patients treated with albuterol were less likely to be coughing after 7 days compared to erythromycin (41% vs 88%, P < .05). 5
Albuterol delivered by metered-dose inhaler reduced the likelihood of coughing after 7 days compared to placebo (61% vs 91%, P = .02). 6
However, these findings must be weighed against the more recent Cochrane review and guideline recommendations that found no consistent benefit in unselected populations. 2
Critical Clinical Decision Points
When to Consider Bronchodilators:
- Wheezing is present on physical examination at the onset of illness. 2, 4
- Evidence of airway obstruction at presentation. 2
When NOT to Use Bronchodilators:
- Absence of wheezing or airflow obstruction. 2
- Routine use in all patients with acute bronchitis. 3, 2
Objective Assessment Required
If a therapeutic trial is initiated, response must be objectively assessed; if no documented improvement occurs, treatment should be discontinued. 2
Important Diagnostic Pitfalls
Do not confuse acute viral bronchitis with exacerbation of COPD or asthma, where bronchodilators are clearly indicated. 2
Approximately one-third of patients diagnosed with "recurrent acute bronchitis" actually have undiagnosed asthma or COPD. 1
Before diagnosing acute bronchitis, rule out pneumonia by checking for heart rate >100 bpm, respiratory rate >24 breaths/min, temperature >38°C, or abnormal chest examination findings. 1
Anticholinergic Agents
The effect of inhaled anticholinergic agents (such as ipratropium) on cough in acute bronchitis has not been studied and therefore cannot be recommended based on evidence. 2
Ipratropium bromide is recommended only for chronic bronchitis, not acute viral bronchitis. 3
What NOT to Use
Expectorants and mucolytics are not recommended, as their beneficial effects have not been proven for acute bronchitis. 2
Routine antibiotics provide no benefit (reducing cough by only ~0.5 days) while causing adverse effects. 1