Your body does not have antibodies (things that make the immune system attack) the first time you are exposed to an allergen (thing you are allergic to). After the first exposure the antibodies are circulating in your blood and the reaction is much quicker. The reaction will become worse every time an exposure occurs. Sprintflyer is right he does need to carry and epi pen from now on. If he needs to use the epi pen he should be seen because the reaction can still be going on after the epi wears off. The epi does not stop the reaction. It dilates your bronchioles (air passages in the lungs) and constricts you blood vessels keeping your blood pressure from dropping critically low. Benedryl (Diphenhydramine) and steroids will stop the reaction. Benedryl is an antihistamine and steroids temporarily shut off the immune system.