When you get a shot for a vaccine (for example, the annual flu vaccine), the nur

Question

When you get a shot for a vaccine (for example, the annual flu vaccine), the nurse frequently indicates that your arm will ache for a day or two, maybe more. This ache is typically not just a pain from having your skin punctured, but is actually an ache of the entire arm.

What mechanism causes the entire arm to ache from a vaccine? Why doesn't that ache extend to other parts of the body, like the hands or the shoulders? Why do non-vaccine arm punctures (such as drawing blood, injecting drugs) not cause the ache?

Explanation / Answer

The goal of the vaccine is to provoke an immune answer, therefore some degree of inflammation is expected in order for the vaccine to work.

Since you get the shot intramuscularily, intradermally or subcutaneously, it is local, and the inflammation does not spread. The reason why your whole arm seems to hurt (rather than the place where the vaccine was deposited) is, I think, that where you got your shot, you have not many pain receptors, and your brain is not able to determine the pain source very exactly.

Related Questions

Navigate

• Browse (All)
• Browse W
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.