i found this in this article <link> : one of the most serious problems that can come from getting the vaccine is an allergic reaction. that happens in less than one out of a million doses. if it were going to happen it would most likely happen within a few minutes to a couple of hours after taking the vaccine. and even though it's rare it's important to be alert for an allergic reaction with any medicine and get medical help at once if it occurs. symptoms might include any of the following: difficulty breathing hoarseness wheezing hives paleness weakness rapid heart beat dizziness it is probably wise to contact your doctor and let them know what you are experiencing.
possible tdap allergic reaction? hives? . i had a tdap shot last saturday and have had hives off an on all week. could this be an allergic reaction even though it wasn't sudden?