Most people do not have serious problems after being vaccinated. Side effects may feel like flu and even affect your ability to do daily activities, but they should go away in a few days. Often times, people will have symptoms like mild fever, tiredness, and body aches after getting a vaccine. These symptoms are normal and signal your body's immune response to the vaccine to help you prevent future infections. Learn about common side effects and get helpful tips on how to reduce your pain and discomfort from the CDC.