On this page:
- Possible side effects
- Rare but serious side effects
- Immunization aftercare sheets
- Reporting of adverse events
- Vaccines and health conditions
- It's much safer to get the vaccine than the disease
- Canada's vaccine injury support program
Did you know?
- Pain, redness, or swelling where the vaccine was given.
- Tiredness or headache.
- Fever and chills.
- Muscle or joint soreness.
- Nausea, vomiting, or diarrhea.
- Fussiness, crying, restlessness, or decreased appetite in infants
After the MMR or chickenpox (varicella) vaccine: fever, rash, or other side effects (including swelling of glands in the cheeks or neck after the MMR vaccine) may occur one to two weeks after immunization.
After the nasal spray influenza (flu) vaccine: nasal congestion and runny nose.
Click the images below to learn what to expect after immunization and how to manage side effects.
What is an adverse event?
An adverse event following immunization (also known as an AEFI) is any untoward medical occurrence after a vaccine has been given that may or may not have been caused by the vaccine.
- Chickenpox (varicella) infection can cause pneumonia.
- Polio infection can cause permanent paralysis.
- Measles infection can cause encephalitis (swelling of the brain).
- Mumps infection can cause deafness.
- Haemophilus influenzae type b (Hib) infection can cause brain damage or even death.
- Rotavirus infection can cause severe vomiting and diarrhea, which can result in dehydration and hospitalization.
- Shingles can cause pneumonia (an infection of the lungs), loss of hearing or vision, scarring, nerve pain, and brain inflammation (encephalitis).