Reactions to vaccines are common and almost always harmless. Severe allergic (anaphylactic) reactions to any vaccine are possible, but they are extremely rare or have never been reported. Listed below are the symptoms for a severe allergic reaction as well as common reactions to specific vaccines.
A severe reaction is very rare. If it does happen, it is almost always within 20 minutes after the immunization. Seek help immediately or call 911 if you notice the following severe allergic reactions:
The percentage listed next to each reaction shows the percentage of children who have this reaction.
CALL YOUR PROVIDER IMMEDIATELY IF the following rare but serious reactions occur:
Measles, Mumps, Rubella (MMR)
These reactions may begin 5 to 12 days after getting the vaccine:
Polio Vaccine (IPV)
Pneumococcal Conjugate Vaccine (PCV)
Haemophilus Influenza Type B Vaccine (Hib)
Hepatitis B Vaccine (Hep B)
Chickenpox Vaccine (VAR)
Children with these rashes can go to day care or school. If the vaccine rash contains fluid, cover it with clothing or a Band-Aid. Avoid school if there are widespread, weepy sores (because this may be real chickenpox).
Hepatitis A Virus (HAV) Vaccine
Influenza Virus Vaccine (Injection)
Influenza Virus Vaccine (Intranasal)
Some children who get the nasal spray form of the flu vaccine will have symptoms such as:
These symptoms do not last long and go away on their own.
Meningococcal Conjugate Vaccine (MCV)
Human Papillomavirus Virus Vaccine (HPV)
Fainting is very rare after receiving a vaccine. Anyone receiving a vaccine should be observed for 15 minutes after the shot.