J.
It could be the medium the vaccine is prepared in or the preservative possibly. Any one could express allergic reaction to almost anything anytime in their life. Benadrl is a short term solution. You might need a shot of epinephrine such as in an Epi-pen. In general I would not wait till it is convenient to go to the ER or a local doctor for an allergic reaction. It can be very serious not something to self medicate except for a very short time. The fact the hives are spreading is serious. If I were you head over to an ER tonight if can put up with waiting 2-3 hrs to be seen. But for an allergic reaction they may pretreat you as they dont want liability! It can cause the throat to close up and make it hard to even breath! that is Extremely and emergecy then! then call an Ambulance to take you! Sorry to give this news but my brother suffers from allergy to Ginseng and when he was at a summer college program and the clinit in the country was closed he called my Dad an MD. He said he could barely dial the phone since his fingers were swelling. My Dad immediatly said he would drive up to him which was over an hr. Drive! To give him what he needed. Best of Luck! Maybe not it is getting better if not GO! IMO