Vaccine safety and possible side effects
On this page
- Vaccine side effects
- Allergic reactions
- Stress-related reactions
- Making sure vaccines are safe
- Vaccine ingredients
- Vaccine Injury Support Program
- Vaccination for COVID-19
- Immunity from disease and disease prevention
Vaccine side effects
Like any medication, vaccines can cause side effects and reactions.
After being vaccinated, it's common to have temporary side effects. These usually last from a few hours to a few days after vaccination.
This is the body's natural response, as it's working hard to build immunity against the disease. Most side effects don't disrupt daily activities.
Common vaccine side effects may include:
More general symptoms can include:
- joint pain
- mild fever
- muscle aches
Children may also be more fussy than usual after vaccination. Talk to a health care provider about how to help manage common side effects.
If you or someone in your care experiences any unusual symptoms after vaccination, call a health care provider or your public health unit.
There's a small chance of a serious allergic reaction to a vaccine called anaphylaxis. It usually happens shortly after a person receives the vaccine and is treatable.
Your health care provider will ask you to stay at the clinic for at least 15 minutes after vaccination. This is so they can watch for abnormal or very rare reactions and treat them quickly. Vaccination sites should have a supply of epinephrine to use in case you have an allergic reaction.
Signs and symptoms of anaphylaxis may include:
- itchy rash
- swelling of the:
- increased heart rate
- loss of consciousness
- sudden low blood pressure
- abdominal pain, vomiting and diarrhea
- sneezing, coughing and difficulty breathing
If you experience any of these symptoms at the vaccination site, report it to your health care provider.
Call emergency services right away if you have left the vaccination site and develop any serious symptoms that could be an allergic reaction.
Anaphylaxis in children
It may be hard to identify anaphylaxis in children who are too young to describe their symptoms. Signs of anaphylaxis in children may include:
- hives, flushing and swelling of the face
- lack of control over bladder and bowels
- behavioural changes, such as:
- crying that doesn't stop
- sudden quietness or sleepiness
- vomiting (including persistent vomiting)
Alert a health care provider if you're waiting after the vaccine and think that your child is experiencing signs of an allergic reaction.
Seek immediate medical attention if you have left the vaccination site and think your child is experiencing signs of a serious allergic reaction.
Health Canada and the Public Health Agency of Canada closely monitor reports of side effects after vaccination. This is to continue to ensure vaccine safety and that benefits outweigh the known risks. We have systems in place to monitor safety and to alert medical experts of unusual post-vaccine events.
Stress-related reactions, including pain, fear and fainting, are potential side effects of vaccination. They can make people uncomfortable or afraid of vaccinations, which can be a barrier to future vaccination.
A small number of people who are very anxious about vaccines may:
- turn pale
- start to sweat
- feel lightheaded or dizzy
- feel numbness or tingling
- start to breathe very quickly
- feel loss of sensation in the face, hands or feet
These symptoms can lead to fainting during or shortly after receiving a vaccine. People may remain pale and sweaty, and have low blood pressure for several minutes afterwards. Fainting can cause head injuries if there's a fall.
Let a health care provider know if you have a high fear of needles or a history of fainting before, during or after vaccination. You may be able to receive your vaccine lying down. This way health care providers can prepare for and manage these side effects.
Learn more about:
- About Kids Health: CARD system
- A Parent’s Guide to Vaccination
- An Adult's Guide to Vaccination
- Immunize Canada: Pain management during immunizations for children
Making sure vaccines are safe
The benefits of all recommended vaccines outweigh any known risks. Health Canada evaluates vaccines before approving them for use to make sure they:
- prevent diseases
- show no safety concerns
Once a vaccine has been approved for use in Canada, we monitor it for:
- effectiveness (how well it works)
Health Canada and the Public Health Agency of Canada share the responsibility for ongoing safety monitoring, which also involves:
- the public
- the vaccine industry
- health care professionals
- provincial, territorial and local public health authorities
Safety monitoring continues even after vaccines are approved for use in Canada.
The active components in vaccines are called antigens. Antigens build an immune response in the body and can also recognize future disease exposures.
Vaccines also contain small amounts of other ingredients. Each ingredient serves a specific purpose.
Learn more about:
- Vaccine safety video
- Vaccine safety poster
- Regulating vaccines for human use in Canada
- Vaccine development and approval in Canada
Vaccine Injury Support Program
Canada has very high standards for vaccine safety. Health Canada only approves vaccines in Canada after a thorough and independent review of the scientific evidence. We work with others to monitor vaccines on the market and can quickly make changes if they identify safety concerns.
As with all vaccines and any medication, there's a chance that there could be serious side effects. These are rare.
On June 1, 2021, the Vaccine Injury Support Program began accepting applications from people in Canada who suffered a serious and permanent vaccine injury.
The program provides financial support to you if it's determined that:
- you've experienced a serious and permanent injury after receiving a Health Canada-approved vaccine and
- the vaccine was administered in Canada on or after December 8, 2020
Financial support is also available to you if you're the dependent or beneficiary of someone who died after vaccination.
Supports may include:
- income replacement
- payment for injuries
- death benefits, including funeral expenses
- other eligible costs, such as uncovered medical expenses
Learn more about:
If you were vaccinated in Quebec
The Government of Quebec has a pre-existing program. If you were vaccinated in Quebec, you must apply for support through this program instead.
Learn more about:
Vaccination for COVID-19
Vaccination is one of the most effective ways to protect against severe outcomes of COVID-19.
Learn more about:
Immunity from disease and disease prevention
Vaccines help your immune system get ready to protect itself against disease.
You may gain some immunity after being exposed to a disease. However, the risks of severe complications or death are much greater than the risks of a severe reaction after getting a vaccine.
An infected person can also spread the disease to others in the community before they show symptoms. Groups at greater risk of severe consequences in the community include:
- older adults
- the very young
- pregnant people
- those with underlying health conditions
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