Part of our treatment of allergic reactions in my ED is solumedrol or decadron, and pepcid, in addition to benadryl. Is this person allergic to benadryl specifically? or multiple antihistamines? If they are having respiratory symptoms you can also give albuterol/atrovent nebulizers or racemic epi. If the reaction is to benadryl specifically, they could also be given different antihistamine meds in addition to those already listed.