Background and Objective: Acute bronchiolitis during infancy is the most common cause of respiratory tract infections. The purpose of this study was to evaluate the effects of a single intramuscular injection of dexamethasone on infants less than 2 years old suffering from acute bronchiolitis.

Materials and Methods: In this double blind randomized clinical trial, sampling was random and from available patients. Eighty infants under 2 years of age were admitted to the Mohammad Kermanshahi hospital. With the first episode of wheezing in the emergency department, bronchiolitis was diagnosed. The patients were randomly divided into 2 groups, a drug group (1mg/kg dexamethasone) and a placebo group. The primary outcome was RDAI score, 4 hours after arrival and the secondary outcome was RDAI score, 7 days after arrival.

Results: A difference in the average of RDAI score at the time of arrival in the dexamethasone group
(4 ±1.49) versus placebo group (4.29 ±1.4) was not statistically significant. The mean RDAI score 4 hours after arrival in the dexamethasone group was 1.7±1.2, while in the placebo group it was 3.66±1.07. Mean RDAI score 7 days after arrival in the dexamethasone group was 0.5±0.4 while in the placebo group it was 0.85±0.71 which is significant.

Conclusion: Based on these results, it seems that a single dose of intramuscular dexamethasone in infants with acute bronchiolitis was effective in reducing RDAI score 4 hours and 7 days after arrival.