Common Vaccine Side Effects

Vaccines, like any medicine, can have side effects. For most vaccines, serious side effects are extremely rare. The risks of vaccines are much lower than the risks of the diseases they prevent.

Different vaccines have different side effects, most of which are mild. They include:

  • temporary pain
  • redness, swelling, or soreness where the shot was given
  • short-lived flu-like symptoms

These side effects happen in one out of four children who receive vaccinations. They appear shortly after the shot is given and should go away after one or two days. If these symptoms persist, talk to your child's doctor. 

Temporary pain, causing a fear of vaccines 

Fear or 'needle phobia' is a common side effect of vaccines. About 1 in 10 people avoid immunization and other needle procedures because they experienced pain from a previous shot. If your child is feeling anxious, stay calm, distract and comfort them. Visit our pain-free injections page to learn how you can make vaccinations as easy and pain-free as possible.

Redness, swelling, or soreness where the shot was given

Your child may have a reaction shortly after receiving the vaccine. This may include redness, swelling, soreness, or bruising in the area where the shot was given. A cool, wet cloth can be used to ease your child's discomfort.

Flu-like symptoms

After getting the vaccine, your child may develop some flu-like symptoms. These include:

  • mild fever
  • upset stomach
  • vomiting
  • loss of appetite
  • headache
  • fatigue

Vaccines work by imitating the infection, sometimes causing flu-like symptoms. This infection does not cause illness. Rather, it trains the body to develop the right response. If the flu infects a vaccinated person, the body is now able to recognize it and fight it off.

When to see a doctor for vaccine side effects

Serious side effects from immunization are very rare, but they can happen. They may include:

  • serious allergic reaction or anaphylaxis, including itching, rash, swelling around the mouth and face, trouble breathing, and low blood pressure
  • seizures
  • high fever
  • joint pain or stiffness
  • pneumonia

If your child is showing any of these serious side effects, or if you are worried, contact your child's doctor or go to the nearest Emergency Department.

Key points

  • The risks of vaccines are much lower than the risks of the diseases that they prevent.
  • The most common vaccine side effects are mild and may include temporary pain, redness or swelling in the area where the shot was given, and flu-like symptoms.
  • Serious side effects from immunization are very rare. If your child is showing serious side effects, or if you are worried, contact your child's doctor or go to the nearest Emergency Department.
8/23/2012




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