Do You Believe My Body Will React Negatively Due To A Foreign Substance Like A Flu Shot?

I would classify myself a healthy 20 year old female. I have not taken a single pill for 5 years now (say pain releiver like advil, aleve, asprin or antibiotics) I have never been on birth control and my diet is clean with no processed foods. Soon, I have to take the flu shot, but I am reluctant my body will respond negatively. Do you believe my body will react negatively due to this foreign substance?