Vaccines can contain proteins that are capable of inducing an allergic reaction. Symptoms are identical to any other type of allergic reaction – itching, hives, difficulty breathing, cough, low blood pressure, and fainting. It is important to be evaluated by an allergist to confirm an allergy to a vaccine because it can affect future vaccinations.

Some vaccines are manufactured using egg embryos and as a result, have caused egg allergic individuals to avoid the flu vaccine. The amount of egg protein in the flu vaccine is very minimal and is unlikely to cause a reaction. However, for those with a severe egg allergy, it can be administered in multiple doses over a longer period of time to decrease the risk of a serious reaction.