If a child is experiencing a serious allergic reaction to food, it is recommended to use an Epipen as Benadryl may not act quickly enough to control a sudden severe reaction. You can obtain an Epipen for a child at a pharmacy, where the pharmacist can prescribe it so that the costs are covered by insurance. It is important to administer the Epipen and then go to the emergency room as soon as possible if a child is having a reaction to food, as the effects of the Epipen are temporary.