Well some pretty common reactions are a slight fever or even noticing that your son has some pain at the injection site.

Pay attention to if you are really concerned because the next list are reasons to call or go the doctor:

*A fever of 102 f or more

*If you have having a hard time getting your child to wake up

*Seizure

*Hives, noticing trouble breathing, something that looks as though it is an allergic reaction.

*Excessive vomiting or diarrhea

Better safe than sorry, so if you feel as though there is something wrong then please ask your doctor.