3. Fever
Normal human temperature is usually around 98.6 degrees Fahrenheit, and you could experience a slight fever that persists for a couple of hours after you’ve had your flu shot. In most cases this is nothing to worry about and just another way for your body to respond to the presence of anything foreign – your body’s immune system usually creates a fever to try and create an environment that cannot be habituated by germs.
This is why you usually get a fever when you are sick with any type of infection – and it also happens to be why you get a fever when you’ve had your flu shot. Your body is tricked into thinking that it has a mild form of the flu virus – and some people’s bodies will respond to this by countering with symptoms that can include fever or replication of the minor flu.
This usually doesn’t last long, though if it continues for more than a day after you’ve had your shots, you should see a doctor.