text: If you get a flu shot, you are getting viral particles that have been raised in chicken eggs and inactivated by treatment with formalin.\n\nIf you got the flu mist thing, you get a weakened virus of some sort.\n\nAnyhow, you can feel like garbage after getting the shot because you are experiencing an immune reaction to what was injected (that's the point!), as your body recognizes that something is there that shouldn't be.  You don't get the flu because the viral particles are unable to do anything because the of the formalin treatment.  This year my arm hurt for an hour or so, but that was all.