What should you do if you get hives after a flu shot?

See below: As long as you are not having any trouble breathing, the best thing to take is benadryl (diphenhydramine). I would also contact your provider.

Flu shot allergy: Take Benadryl (diphenhydramine) to counteract the hypersensivity and relieve the itch. Consult your doctor to ascertain whether it's allergy to the influenza virus or to egg. If you experience trouble with your breathing, rush to the ed.