Can a fever from flu shot be contagious?

A fever is a common side effect of the flu vaccine. However, it is not contagious. The flu shot contains only dead viruses, so it cannot cause the flu.

A fever is a natural response to infection or injury. It is the body's way of trying to kill off germs and repair damaged tissue. When a person has a fever, their body produces more white blood cells, which are essential for fighting infection.

The flu vaccine can cause a fever because it stimulates the body's immune system to produce antibodies against the flu virus. This process can cause the body to release pyrogens, which are chemicals that cause the body's temperature to rise.

Most people who get a fever from the flu shot will develop it within 24 hours of receiving the shot. The fever typically lasts for 1-2 days. It is important to note that not everyone who gets the flu shot will develop a fever. In fact, only about 10-20% of people who get the flu shot will experience a fever.