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Vaccine Side Effects

vaccine side effects graphic

It is important to understand that any vaccine can cause side effects (adverse event). The CDC defines an adverse event as any health problem that happens after vaccination.83 An adverse event can be a true adverse reaction, also known as a side effect, that is related to the vaccine, or a coincidental event that happened following vaccination.83

There are a few different types of adverse events that may occur after vaccinations:

  • Adverse Reactions (side effect)- are considered to be caused by a vaccine. Many of the common side effects are identified during clinical trials. The intensity of these reactions may range from mild, to moderate, to severe. They often resolve on their own and may or may not require medical intervention.83
  • Unrelated health problem- are health events, that occurred following a vaccination, that would have occurred even if the person was not vaccinated.83
  • Unknown health problems- are health events, that occurred following a vaccination, with an unknown cause. Meaning there is not enough evidence to say whether it was caused by the vaccine or would have occurred even if the person was not vaccinated.83

What are the Most Common Side Effects of Vaccines?

Vaccines, like medicine, can have some side effects. When you get a vaccine, it sparks your immune response, helping your body fight off and remember the germ so it can attack it if the germ ever invades again. When your immune system is activated, it is the body’s natural defense to have some tiredness and discomfort. Although it is uncomfortable, the side effects of vaccines are generally minor and go away within a few days. Such minor symptoms are normal and should be expected as the body builds immunity.84

Below are common side effects of vaccines84:

  • Pain, swelling, tenderness, or redness where the shot was given
  • Mild fever
  • Chills
  • Feeling tired
  • Headache
  • Muscle, body, and joint aches

What About Serious Side Effects?

Serious side effects from vaccines are extremely rare. For example, if one million doses of a vaccine are given, 1-2 people may have a severe allergic reaction.84

Signs of a severe allergic reaction can include84:

  • Difficulty breathing
  • Swelling of your face and throat
  • A fast heartbeat
  • A bad rash all over your body
  • Dizziness and weakness

But there are so many vaccines, so how do I monitor for each vaccine?

Different vaccines work in different ways, but every vaccine helps the body’s immune system learn how to fight germ. It is important to understand that vaccines are continually monitored for safety, and like any medication, vaccines can cause side effects. The CDC has created information sheets specific for each recommended vaccine to help provide adequate, up-to-date information for each vaccine.85

To read more about each specific vaccine that is licensed in the United Stated and the side effects that have been associated with each of them, visit the CDC, possible side effects of vaccines.

Vaccine Information Statements (VISs) are information sheets produced by the CDC that explain both the benefits and risks of a vaccine.85

All vaccine providers, public or private, are required by the National Vaccine Childhood Injury Act86 to give the appropriate VIS to the patient (or parent or legal representative) prior to every dose of specific vaccines.

To find the current VIS, visit the CDC.87