Ask an Expert
How do I know if my baby is having an immunisation reaction?
8th September 2015
An allergic reaction to a vaccination is rare, and happens shortly after the vaccination (which is why your doctor asks you stay for about 10 minutes after the injection).
Side effects like redness or swelling at the injection site, irritability, or a fever are the most common reactions, but they still don’t happen often – occurrences range from 5-20% depending on the vaccine.
Each vaccine – and child – is different, so side effects vary. For example, with the measles/mumps/rubella (MMR) vaccination, reactions like fever, rash, and loss of appetite can develop six to ten days later. Reactions to the diphtheria/ tetanus/pertussis/polio/Haemophilus influenzae type b (DTaP/IPV/Hib v) vaccine usually appear within 24 hours and last for only a few days at most.
If you have any concerns before or after your child’s vaccinations, speak to your doctor or nurse.