Are You Having an Allergic Reaction to the Flu Vaccine?

Flu vaccines are recommended for nearly everyone. They aren't perfect, but they are the best protection we have against influenza, or the flu virus. The flu is a serious illness that kills thousands of people each year. Unfortunately, many people are resistant to getting flu vaccines. The reasoning for declining flu shots vary, but may include anything from being misinformed about their efficacy to concern about potential reactions.

Some side effects are common with flu vaccines, while others are less so. Side effects don't usually preclude you from getting a flu vaccine in the future while a true allergic reaction does. Read on to learn how to distinguish between the two.

Common Side Effects

A lot of people have mild reactions to getting the flu vaccine. Of course, the injection can be slightly painful, but other common side effects include:

  • Soreness at the injection site and the surrounding muscle
  • Low-grade fever
  • Minor body aches
  • Headache
  • Nausea

If you get the nasal spray flu vaccine, side effects may include:

  • Runny nose
  • Wheezing
  • Headache
  • Vomiting
  • Muscle aches
  • Fever
  • Sore throat
  • Cough

Additionally, while FluMist, or the nasal spray flu vaccine, was not available in the U.S. in recent seasons flu season due to concerns about its effectiveness, it's back this year because manufacturers have used a new H1N1 vaccine virus in production that is expected to be improved.

Signs of an Allergic Reaction

True allergic reactions to flu vaccines—or any vaccines—are extremely rare. An estimated one in one million doses of a vaccine causes an allergic reaction. However, it's important to know the difference between a real allergic reaction and a side effect. Since allergic reactions do happen occasionally, it's still important to know what to watch for.

Symptoms of a Severe Allergic Reaction

  • Difficulty breathing
  • Hoarseness or wheezing
  • Swelling around the eyes or lips
  • Hives
  • Paleness
  • Weakness
  • A fast heartbeat or dizziness

A small rash at the injection site is not considered a severe allergic reaction. Soreness at the injection site or in the muscle where the vaccine was injected is normal and should resolve within a day or two.

Other Serious Adverse Reactions

Even if you don't have a true allergy to an ingredient in the flu vaccine, you may experience a reaction that is serious enough to warrant avoiding the vaccine in the future.

Guillain-barré syndrome (GBS) is an autoimmune disorder that can sometimes be triggered by the flu vaccine. It is very rare and occurs more often after a respiratory or gastrointestinal illness than it does after a vaccination.

GBS typically begins with weakness or tingling in the feet or legs. Weakness and paralysis often extend up the body. In severe cases, it may interfere with breathing or other organ functioning. The rate at which it progresses varies, but most people experience the worst symptoms two to three weeks after the onset. A vast majority of people with GBS fully recover, but some may experience permanent weakness and it is occasionally fatal.

There was a slight increase in the number of cases of GBS among people who received a pandemic flu vaccine in the late 1960s. However, no definitive link has been established for any other flu vaccines since that time.

The rate of GBS among vaccinated people and unvaccinated people today is equal. However, due to this possible connection, anyone who has had Guillain-barré syndrome within six weeks of a flu vaccination in the past should not get one again.

There are also some concerns about people with severe egg allergies having flu shots. Most flu vaccines are grown in eggs contain a small amount of egg protein. In the past, it was recommended that people with an egg allergy avoid them. However, because research has shown that severe allergic reactions are unlikely whether or not you have an egg allergy, recommendations from the CDC now state that nearly everyone with an egg allergy can be vaccinated against the flu.

What You Should Do

If you think you are having a severe allergic reaction to a flu vaccine, seek medical attention immediately. Additionally, if you're experiencing any unexpected pain or effects after receiving the vaccine that you believe may be an emergency, you should contact your provider. You should also report it to the Vaccine Adverse Event Reporting System (VAERS). Either you or your doctor can report a concern about a reaction to a flu vaccine through this system.

Finally, if you or your doctor believes your symptoms could have been caused by the flu vaccine, you can file a claim with the National Vaccine Injury Compensation Program, which is a a no-fault alternative to traditional legal proceedings for resolving vaccine injury petitions. Even if a finding isn't made, you may be eligible to receive financial compensation through a settlement.

A Word From Verywell

True allergic reactions to flu vaccines are extremely rare, and this potential risk should not deter you from getting the vaccine. However, we share this information so you know what to watch for and are able to act accordingly. If you have questions or concerns about your own symptoms after a vaccine of any kind, please contact your provider to determine the proper course of action.

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Article Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial policy to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. Influenza (flu). What you need to know for 2019-20. October 8, 2019.

  2. Centers for Disease Control and Prevention. Influenza (flu). Flu Vaccine and People with Egg Allergies. December 28, 2017.

  3. Health Resources & Services Administration. National Vaccine Injury Compensation Program. June 2019.

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