The flu vaccine can't give you the flu. But you might develop flu-like symptoms — despite getting a flu shot — for a variety of reasons, including: Reaction to the vaccine. Some people experience muscle aches and a fever for a day or two after receiving a flu shot.
How long after flu shot can you get side effects?
Rarely, people who get the flu shot have fever, muscle pain, and feelings of discomfort or weakness. If experienced at all, these effects usually last for 1-2 days after vaccination and are much less severe than actual flu illness.
Are there side effects to the flu shot?
According to the CDC, mild side effects from the flu shot include soreness, redness or swelling at the injection site, low-grade fever and aches. Only about 1 percent to 2 percent of people who get a flu shot will have fever as a side effect, Schaffner said.