Despite the large variety of inhaled treatment options of acute bronchiolitis, there is no generally agreed treatment regime. This study aimed to determine the most appropriate treatment option. This was a double-blind randomized prospective clinical trial and has been performed in emergency department. The mean age of the 378 infants included in the study was 7.63 +/- 4.6 months, and 54.8% (207) were boys. Patients were randomized by using the lottery method for simple random sample into 5 different treatment options; 3% hypertonic saline, nebulized adrenaline, nebulized adrenaline mixed with 3% hypertonic saline, nebulized salbutamol, and as control group; normal saline (0.9% NaCl). From the first treatment time until discharge time; treatment durations, adverse events and readmission rates within the first fifteen days were recorded for each patient. Nebulized adrenaline mixed with 3% hypertonic saline, as compared with other options, were associated with a significantly higher discharge rate at 4th hours (p<0.001) and shorter length of hospital stay (p=0.039). However, there was no significant difference between options with regard to adverse events, discharge rates at 24th hours, and readmission rates within the first fifteen days. The superiority of discharge rates at 4 hours of nebulized adrenaline mixed with 3% hypertonic saline, was evaluated as 'better acute response' and can be helpful to reduce hospitalization needs. Additionally, this option seems to be more effective to reduce length of hospital stay.