Flu vaccines have a good safety record. Hundreds of millions of Americans have safely received flu vaccines over the past 50 years, and there has been extensive research supporting the safety of flu vaccines.
A flu vaccine is the first and best way to reduce your chances of getting the flu and spreading it to others. CDC recommends that everyone 6 months of age and older receive a flu vaccine every year.
No, the flu vaccine cannot cause flu. The vaccines either contain inactivated virus, meaning the viruses are no longer infectious, or a particle designed to look like a flu virus to your immune system. While the nasal spray flu vaccine does contain a live virus, the viruses are changed so that they cannot give you the flu.
Like any medical product, vaccines can cause side effects. Side effects of the flu vaccine are generally mild and go away on their own within a few days.
Common side effects from the flu shot include:
- Soreness, redness, and/or swelling from the shot
- Headache
- Fever
- Nausea
- Muscle aches
The flu shot, like other injections, can occasionally cause fainting.
Some studies have found a possible small association of injectable flu vaccine with Guillain-Barré syndrome (GBS). Overall, these studies estimated the risk for GBS after vaccination as fewer than 1 or 2 cases of GBS per one million people vaccinated. Other studies have not found any association. GBS also, rarely, occurs after flu illness. Even though GBS following flu illness is rare, GBS is more common following flu illness than following flu vaccination. GBS has not been associated with the nasal spray vaccine.
With any vaccine, look for any unusual conditions, such as a high fever, behavior changes, or signs of a severe allergic reaction after vaccination.
Signs of a severe allergic reaction can include:
- Difficulty breathing
- Hoarseness or wheezing
- Swelling around the eyes or lips
- Hives
- Paleness
- Weakness
- A fast heart beat or dizziness
Life threatening allergic reactions to the flu shot are rare. These signs would most likely happen within a few minutes to a few hours after the vaccine is given.
If you think it is a severe allergic reaction or other emergency that can’t wait, call 9-1-1 and get to the nearest hospital. Otherwise, call your doctor.
Afterward, the reaction should be reported to the Vaccine Adverse Event Reporting System (VAERS). Your doctor might file this report, or you can do it yourself through the VAERS website, or by calling 1-800-822-7967.
If you believe you have been injured by a flu vaccine you may be eligible to receive compensation from the federal government for your injuries if certain criteria are met. To learn more visit the National Vaccine Injury Compensation Program website or call 1-800-338-2382.
CDC recommends everyone 6 months of age and older should receive an annual flu vaccination with rare exceptions. Individuals who can’t get the flu shot include:
- Children younger than 6 months, since they are too young to get a flu shot.
- Individuals with severe, life-threatening allergies to flu vaccine or any ingredient(s) in the vaccine.
Individuals should talk with their doctor before getting the flu shot if they:
- Have had a severe allergy to eggs or any of the ingredients in the vaccine. (See Special Considerations Regarding Egg Allergy for more information about egg allergies and flu vaccine.)
- Have had Guillain-Barré syndrome (GBS).
- Are not feeling well.
There are multiple flu vaccines available, and not all flu vaccines can be given to people of all ages. Talk to your doctor if you have any questions regarding which flu vaccine options are best for you and your family. See Vaccination: Who Should Do It, Who Should Not and Who Should Take Precautions) for more information.
Yes, pregnant women should get a flu shot to protect themselves and their developing babies. To learn more about flu vaccine safety during pregnancy, visit Flu Vaccine Safety and Pregnancy.
CDC and the Food and Drug Administration (FDA) closely monitor the safety of vaccines approved for use in the United States. CDC uses two primary systems to monitor the safety of flu vaccines:
- Vaccine Adverse Event Reporting System (VAERS): an early warning system that helps CDC and FDA monitor problems following vaccination. Anyone can report possible vaccine side effects to VAERS. Generally, VAERS reports cannot determine if an adverse event was caused by a vaccine, but these reports can help determine if further investigations are needed.
- Vaccine Safety Datalink (VSD): A collaboration between CDC and nine health care organizations which allows ongoing monitoring and proactive searches of vaccine-related data.
People with egg allergies can receive any licensed, recommended age-appropriate influenza vaccine (IIV, RIV4, or LAIV4) that is otherwise appropriate. People who have a history of severe egg allergy (those who have had any symptom other than hives after exposure to egg) should be vaccinated in a medical setting, supervised by a health care provider who is able to recognize and manage severe allergic reactions. Two completely egg-free (ovalbumin-free) flu vaccine options are available: quadrivalent recombinant vaccine and quadrivalent cell-based vaccine.
Content last updated September 17, 2019