Health & wellness

Health Answers

Can the flu vaccine make you feel sick?

Q. Can the flu vaccine make you feel sick?

A. With flu season hitting early and severely this year, many people are scrambling to get the flu vaccine, which is recommended for everyone 6 months and older. A common excuse to skip the flu shot is concern about feeling sick from the vaccine itself.

“There are a lot of misconceptions out there,” says Andrew Ulrich, executive vice chair of emergency medicine at Boston Medical Center. He emphasizes that there’s no chance of getting the flu from a flu shot. You may experience some soreness or aching at the site of the injection, and some people “get some body aches and feel slightly ill for a day or so,” he says, with headaches or cold-like symptoms. But the effects are no different from what you may experience from other routine vaccinations.


The vaccine does take seven to 10 days to reach its full effectiveness, and Ulrich says that some people may have already been exposed to the flu or become infected shortly after vaccination, and mistakenly believe the vaccine didn’t work or made them sick.

It’s not too late to get the flu shot, since there is probably another month or so in the peak flu season. Because flu strains vary, the vaccine is not completely protective. However, Ulrich says, “getting the flu shot decreases the likelihood of getting sick, and if you happen to get sick will make it less severe.” It also lowers the chance of passing the virus to others.