Vaccination Side Effects and Health Risks

Immunization generally is very safe and most children experience mild side effects, if any, after being vaccinated. Immunization side effects, also called adverse reactions, include the following:

  • Fatigue
  • Fussiness, increased crying
  • Headache
  • Loss of appetite
  • Low-grade fever (below 101°F)
  • Redness, soreness or swelling at the injection site

Side effects from immunizations typically last less than 1 or 2 days. In some cases, pediatricians recommend acetaminophen or ibuprofen to relieve discomfort. If a child experiences a more severe adverse reaction to a vaccine, such as swelling, itching, weakness, dizziness, difficulty breathing, or seizures, notify the child's pediatrician immediately or go to the emergency room.

Recently, there has been some concern that immunizations may cause multiple sclerosis (MS), sudden infant death syndrome (SIDS), autism, or other conditions. However, several studies have shown no connection between immunization and these conditions. For example, the number of SIDS cases has actually decreased by 50% in recent years, even though the rates of immunization have increased.

A small number of children should not be vaccinated because of health issues or allergies. For example, children with cancer or children who have a weakened immune system may not be good candidates for vaccination. Children who have a severe allergy to eggs should not receive the measles-mumps-rubella (MMR) vaccine.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 27 Aug 2008

Last Modified: 14 Aug 2015