What Side Effects Should I Expect after Getting Vaccinated?

Dr. Offit discusses common side effects of vaccines and what they mean.


What side effects should I expect after getting vaccinated?

Speaker 1: So, Dr. Offit, I was wondering what side effects should I expect after getting vaccinated?

Paul Offit, MD: If the vaccine is given as a shot, there can be pain or redness or tenderness at the site of injection that lasts for a day or two. And then the other kind of side effects are really associated with the immune response. When you're inoculated with a vaccine, your body will make an immune response to that vaccine, and that includes making antibodies that bind to and neutralize viruses or bacteria. But associated with all that, your body makes a number of other immunological phenomenon, such as, they have fancy names like cytokines and chemokines, and that's the whole cascade of your immune system.

Well, those proteins, which are associated with fighting off infections, can cause side effects. And those side effects can include fatigue, low-grade fever, headache, joint ache, muscle ache. And again, they're transient. They usually last for a day or two, rarely longer than three days, but that's all part of your immune system.

It's interesting that a friend of mine who lives in North Carolina when he volunteered for one of the COVID trials, he didn't know whether he was going to get a vaccine or placebo. And so, he got the shot and then the next morning when he woke up, he had sort of pain and sort of headache and fatigue and low-grade fever, and he thought, yes, that means I got the vaccine, because he realized that that's all part of the immune system.

So, the immune system does work for you, although sometimes it can cause side effects that at least temporarily are a little bothersome.

Related Centers and Programs: Vaccine Education Center

Last Reviewed on Jan 14, 2022