Intervention: Subjects will be randomly assigned (50% chance) to receive a weight based dose of IM epinephrine 1:1000 or no adjunctive medication. The dose will be 0.2 mg for subjects 20-30 kg and 0.3 mg for subjects greater than 30 kg. This will be injected intramuscularly by an ED nurse into the anterior thigh muscles of the subject using a 1 ml syringe and a 23 gauge one inch needle.