Some more obvious flu side effects of the vaccination are flu-like symptoms. There can be swelling in the neck, armpit or groin. Fever and/or chills may happen. Acquiring the flu shot can have a lot more undesirable side-effects. The individual may vomit; have looseness of the bowels and/or stomach pain. Tingling in the hands and fingers and feet may occur. You may have trouble sleeping. These symptoms typically stop in a couple of days.