Why does my arm hurt after a flu shot?

I get a flu shot every year…just comes with the territory when you are a teacher. Never has it affected my arm like it is right now. Good God my arms is killing me. Did the Doc do something wrong or am I just a wuss. I have an extremely high tolerance for pain…so this is very odd for me. Docs out there…whats the cause of this?

Vaccinations work by giving you a bit of what they are intended to protect you against. Weakened or killed viruses are used to stimulate your body’s immune system to produce appropriate antibodies. I think muscle aches are cause by immune response rather than directly by the virus.

You just got stabbed in the arm.

Any questions?

Did you just get a flu shot? Or any other vaccines with it?

Many vaccines (unsure about this year’s influenza vaccine) contain chemicals called “adjuvants.” These cause some tissue irritation, which activates the immune system in the region. The immune system in that region is then sensitized for new antigens, like the flu proteins or killed antibodies that are injected. Without this, your body ignores many antigens, you don’t make antibodies, and the vaccine doesn’t take. Think of it as “chum” for your immune system.

Obviously, the adjuvants cause much more inflammation than the actual vaccine antigens. This is particularly true of tetanus shots – they use quite a potent adjuvant, which causes your arm to hurt like hell (and even can even cause a low-grade fever).