Why does the flu shot hurt?

Up to 64% of adults and children who receive the flu shot experience pain and/or soreness at the site of the injection, making it the most common side effect of the vaccine. Many patients ... Taking a painkiller will do wonders in reducing swelling and assisting with the discomfort. 3.) Use your arm afterwards. read more

Muscle inflammation. Flu vaccines are generally injected into the deltoid, the muscular part of the arm. It causes inflammation of the area and followed by a slight immune reaction (desired effect). read more

Another thing: Try to keep your arm relaxed (I know, easier said than done). If you tense up your arm muscles, the shot might hurt more, Calderon says. After you get your flu shot, she says, rub the injection area or move your arm around to help spread out the immune response. If necessary, an ice pack will help reduce the aching. read more

Soreness in your arm after getting a flu vaccine typically lasts no longer than one or two days. The pain and inflammation is your body's natural response to a foreign invader. read more