Side Effects to the Seasonal Flu Vaccine

A complete list of possible side effects from both the flu shot and the nasal spray (LAIV or Flu Mist) vaccines are below:

The flu shot: The viruses in the flu shot are killed (inactivated), so you cannot get the flu from a flu shot. Some minor side effects that could occur are:

  • Soreness, redness, or swelling where the shot was given

  • Fever (low grade)

  • Aches

  • Nausea

If these problems occur, they begin soon after the shot and usually last 1 to 2 days. Almost all people who receive influenza vaccine have no serious problems from it. However, on rare occasions, flu vaccination can cause serious problems, such as severe allergic reactions. A federal program has been created to help pay for the medical care and other specific expenses of certain persons who have a serious reaction to this vaccine. For more information about this program, call 1-888-275-4772 or visit the program's website at Countermeasures Injury Compensation Program.

The nasal spray (also called LAIV): The viruses in the nasal-spray vaccine are weakened and do not cause severe symptoms often associated with influenza illness. (In clinical studies, transmission of vaccine viruses to close contacts has occurred only rarely.)

In children, side effects from LAIV can include:

  • Runny nose
  • Wheezing
  • Headache
  • Vomiting
  • Muscle aches
  • Fever

In adults, side effects from LAIV can include:

  • Runny nose
  • Headache
  • Sore throat
  • Cough

Mild problems that may be experienced include soreness, redness, or swelling where the shot was given, fainting (mainly adolescents), headache, muscle aches, fever, and nausea. If these problems occur, they usually begin soon after the shot and last 1-2 days. Life-threatening allergic reactions to vaccines are very rare. If they do occur, it is usually within a few minutes to a few hours after the shot is given. This season’s flu vaccine is made the same way as past seasonal flu vaccines. Millions of seasonal flu vaccines have been given safely. Millions of people have also safely received the 2009 H1N1 vaccine. CDC expects that any side effects following vaccination with the 2010-2011 flu vaccine would be rare. Any side effects that may occur are expected to be similar to those experienced following past seasonal influenza vaccine.

Are there symptoms that should cause concern after getting a flu vaccination?

Signs of a serious allergic reaction can include difficulty breathing, hoarseness or wheezing, swelling around the eyes or lips, hives, paleness, weakness, a fast heart beat or dizziness. In addition, after vaccination you should look for any unusual condition, such as a high fever or behavior changes. If any unusual condition occurs following vaccination, seek medical attention right away. Tell your doctor what happened, the date and time it happened, and when the vaccination was given. Ask your doctor, nurse, or health department to report a possible reaction by filing a Vaccine Adverse Event Reporting System (VAERS) form. Or you can file this report yourself through the VAERS website. You may call 1-800-822-7967 to receive a copy of the VAERS form. VAERS does not provide medical advice.

Are there some people who should not receive this vaccine?

People who have a severe (life-threatening) allergy to chicken eggs or to any other substance in the vaccine should not be vaccinated

Source
2011-2012 Seasonal Influenza (Flu) Vaccine Safety
Centers for Disease Control and Prevention
July, 2012  

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