Q. A 2-year-old boy is brought to the physician by his mother with a harsh nonproductive cough for last three days that have worsened at night. He appears to be in mild distress. His temperature is 100°F, pulse is 145 beats per minute, respiratory rate is 35 breaths per minute, his blood pressure is 90/60 mmHg, and pulse oximetry shows a saturation of 95%. Physical examination shows clear rhinorrhea with a harsh cough. In addition, there is mild inspiratory stridor which resolves with rest. Which one is the most appropriate initial step of management?