A 20-year-old woman complains of difficulty breathing and the feeling of a lump in her throat approximately 10 minutes after being stung by a wasp. Your assessment reveals that she is anxious, is in obvious respiratory distress, and has hives covering her arms and legs. Further assessment reveals diffuse wheezing, a blood pressure of 110/80 mm Hg, and a heart rate of 112 beats/min. You should: