I had an allergic reaction to the flu immunization, seasonal. I realize the reaction had to be from one of the components not the actual immunization. I am trying to figure out which one and how long the reaction will continue. The reaction symptoms return (even over 2 days later) when I try to stop the medications, especially when I go over 6 hours between doses of diphenhydramine. I had/have itching, hives and respiratory constriction. I am not allergic to eggs but am allergic to penicillin. I read that there is a residual antibotic but a sulfa drug, I think: neomycin, which there may be a likelihood of a reaction to when one is allergic to penicillin. From what I understand medication allergic reactions usually are over 1-2 days after one discontinues the medication... but mine was injected so I can't discontinue. How long will the components of the vaccine be active in my body? They will filter out and this reaction, right?