This study is to determine the effectiveness of five-day treatment versus a single dose of oral dexamethasone (corticosteroid) in children between 2 and 24 months of age with a first episode of acute bronchiolitis presenting in the Emergency Department

Inclusion Criteria:

• infants 2 to 24 months of age
• acute bronchiolitis, defined as first episode of wheezing with upper respiratory infection and respiratory distress
• moderate to severe baseline disease severity (Respiratory Distress Index (RDAI) score 6 to 15)
• only patients discharged at or shortly after 240 minutes of uniform stabilization therapy will be randomized

Exclusion Criteria:

• previous wheezing and/or bronchodilator therapy
• hospitalization at 240 minutes
• critically ill patients needing airway stabilization
• patients with low or very high baseline disease severity (RDAI <5 and >16)
• patients under 8 weeks of age
• patients on corticosteroids prior to arrival at Emergency Department
• contact with varicella within 21 days
• past history of ventilation for greater than 24 hours
• existing cardiopulmonary disease, multisystem disease or immunodeficiency
• insufficient command of the English language