Here's everything you want to know about the not-so-fun potential side effect of getting the flu shot, including whether it's actually possible to get the flu from the vaccine.

By Renee Cherry
September 27, 2019
Andrew Brookes/Getty Images

Everyone knows at least one person who's declared they'll never get another flu shot because they've had to suffer through nasty side effects from the vaccine. Actually, it's this desire to avoid side effects was the top reason that Americans decided to skip out on getting the flu shot, according to survey results released before last year's flu season.

If you're needle-averse, it might be tempting to hop on the anti-vax bandwagon, but there's also a lot to be gained from getting the shot each year. Before you put off this year's vaccine on account of potential flu side effects, here's what you should know. (Related: How Long Does the Flu Usually Last?)

Yes, you can have side effects from the flu shot, but in most cases they're NBD. "The most common side effects of the flu shot are local at the injection site," says Gustavo Ferrer, M.D., founder of the Cleveland Clinic Florida Cough Clinic. "People can have soreness tenderness and swelling." It's also possible that'll you'll feel sick afterward. "Small people can have flu-like symptoms such as low-grade fever, muscle aches, tiredness, and headaches that can last a couple of days," says Dr. Ferrer. (FYI FluMist, the flu vaccine nasal spray has comparable side effects.)

While some people get flu-like symptoms from the flu shot, the idea that the shot can give you the flu is a misconception, says flu expert Norman Moore, Ph.D., director of infectious diseases scientific affairs for Abbott. "You cannot get the flu from a flu shot," he says. "The flu vaccine is made with either inactivated flu viruses that are not infectious or with a strain that is genetically engineered so it can't cause disease." So while side effects are a possibility, you at least don't have to worry about causing exactly what you were trying to avoid in the first place.

As with any vaccine, it's possible to have severe side effects from the flu shot if you have an allergic reaction, though that's rare. Trouble breathing, swelling eyes or lips, hives, paleness, weakness, or a rapid heartbeat are all signs of a severe allergic reaction, according to the Centers for Disease Control and Prevention (CDC). The gov agency advises people who know they have a life-threatening allergy to an ingredient in the vaccine to skip it.

Also worth noting, even though there's a new flu shot every season, these possible side effects remain generally the same. Every year, the Food and Drug Administration (FDA) decides on 3-4 strains of influenza the new flu shot should protect against, based on predictions from the World Health Organization (WHO) about which will dominate that year. But regardless of the virus variation from year to year, the side effects really won't vary, reiterates Dr. Ferrer. (Related: Can You Get the Flu Twice In One Season?)

The main takeaway on flu side effects: For most people, the effects of the flu shot amount to a vaccination-site ouchie. In comparison to the common symptoms of influenza, this is definitely the better option.

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