Flu Shot Reactions

While many people receive protection from the seasonal influenza vaccine, some patients experience flu shot reactions that can cause discomfort. A fewer number of patients who receive the shot experience an allergic reaction from the vaccine. The flu shot does not contain the live influenza virus, but it does contain the inactivated virus.

1. Redness and soreness at the injection site. Tenderness around the injection site is a common flu shot reaction for those receiving the injection. Part of the soreness is a reaction to the needle stick, but it is also part of the body’s response to the vaccine.
2. Muscle aches. Muscle aches similar to those you get when you have the flu are another common flu shot reaction. This reaction is also caused by the response of the immune system. The immune system creates antibodies to fight the virus in the injection.
3. Low-grade fever. One of the reasons folks get a flu shot is to avoid flu like symptoms, but some recipients of the shot experience a low grade fever for a couple of days. This is the immune system’s response to an injection of the inactivated virus. This flu shot reaction should only last two or three days at the most. Contrary to popular belief, you cannot get the flu from a flu shot.
4. Allergic reactions. Allergic flu shot reactions is less common than the achiness and flu like symptoms many people experience. The Centers for Disease Control and Prevention warns those with an allergy to eggs to avoid the flu shot. The allergic reaction can be life threatening and cause difficulty breathing, hives, fast heartbeat, weakness and dizziness. The flu shot reaction for those with severe allergies to eggs will begin to occur within a few minutes up to a few hours after the injection.
5. Guillain-Barre syndrome. The Centers for Disease Control and Prevention reports that approximately 1 in 100,000 people will be diagnosed with Guillain-Barre syndrome each year. Studies have shown an association between the flu shot and ultimately developing the illness. According to the Centers for Disease Control and Prevention, about 1 in 1,000,000 may be at risk for Guillain-Barre syndrome as a result of the flu vaccine. Those with a history of the syndrome should discuss the flu shot with their physician before getting the vaccine. While it is not a common flu shot reaction, for some patients, it is a possibility.