The COVID-19 vaccine recommended for most people in Ireland is the Comirnaty vaccine (manufactured by Pfizer). It is a mRNA vaccine.
Comirnaty vaccine side effects
Like all medicines, COVID-19 vaccines can cause side effects. Most of these are mild to moderate and do not last long. Not everyone gets side effects.
If you are concerned about side effects, contact your GP for advice.
Serious side effects, such as a severe allergic reaction, are extremely rare. Your vaccinator is trained to treat allergic reactions.
Most side effects from COVID-19 vaccination do not last long.
Very common side effects
Very common side effects may affect more than 1 in 10 people.
These include:
- tenderness or swelling in your arm where you had the vaccine
- feeling tired
- headache
- muscle pain
- joint pain
- diarrhoea
- fever (temperature of 38 degrees Celsius or above)
- chills
Some of these side effects are slightly more frequent in young people age 12 to 15 than in adults.
In children age 2 to 4, the most common side effects include:
In children age 6 to 23 months, the most common side effects include:
- irritability
- sleepiness
- loss of appetite
- tenderness or redness at the injection site
- fever (temperature of 38 degrees Celsius or above)
Fever after COVID-19 vaccines
It is very common to develop a fever (temperature of 38 degrees Celsius or above) after COVID-19 vaccination. This usually happens within 48 hours of getting a vaccine.
If you feel uncomfortable, take paracetamol or ibuprofen. Follow the instructions on the box or leaflet.
Common side effects
Common side effects may affect up to 1 in 10 people.
These include:
- nausea
- vomiting
- redness in your arm where you had the vaccine
Uncommon side effects
Uncommon side effects may affect up to 1 in 100 people.
These include:
- itchiness where the vaccine was given
- dizziness
- generalised itchiness
- allergic reactions like hives or a rash or swelling in the face
- sleeplessness
- excessive sweating, night sweats
- reduced appetite
- lack of energy or feeling unwell
- pain in the arm you got the vaccine in
Rare side effects
Rare side effects may affect up to 1 in 1,000 people.
These include:
- temporary drooping on 1 side of the face
Very rare side effects
Very rare side effects may affect up to 1 in 10,000 people.
These include:
Myocarditis and pericarditis are inflammatory heart conditions.
The risk of these very rare conditions is higher in young men.
These conditions are more likely to happen after the second dose of the first course of the vaccine. They have mostly been seen within 14 days of getting the vaccine.
Symptoms of myocarditis and pericarditis
Get urgent medical help if you get any of these symptoms in the weeks after your COVID-19 vaccine:
- breathlessness
- palpitations (a forceful heartbeat that may be irregular)
- chest pain
Signs of myocarditis in younger children may be more general including:
- irritability
- vomiting
- difficulty feeding
- rapid and shallow breathing
Extremely rare side effects
Other side effects that may happen after a COVID-19 vaccine include:
- a skin reaction that causes red spots or patches on the skin - the rash can look like a bull's-eye on a dartboard
- unusual feeling in the skin, such as tingling or a crawling feeling
- reduced feeling or sensitivity, especially in the skin
- heavy menstrual bleeding (period) - this is usually not serious and does not last long
Ingredients of Comirnaty COVID-19 vaccine
The Comirnaty COVID-19 vaccine does not contain eggs, preservatives or latex.
You can read more about the vaccine ingredients on the European Medicine Agency's website.
Comirnaty COVID-19 vaccine - ema.europa.eu
Who should not get this vaccine
Most people can safely get the Comirnaty COVID-19 vaccine.
Who should not get the Comirnaty COVID-19 vaccine
This vaccine is not recommended if you:
- had a severe allergic reaction to a previous dose of this vaccine or another mRNA vaccine
- had a severe allergic reaction to any of the ingredients in this vaccine - including polyethylene glycol (PEG)
- were told by a doctor that you should not get an mRNA vaccine
- had a severe allergic reaction after Trometamol (one of the contents in contrast dye used in MRI radiological studies)
Talk to your doctor before getting this vaccine if you:
- had a severe allergic reaction (anaphylaxis) in the past, including to any other vaccine or medicine
- had myocarditis or pericarditis (inflammation of the heart muscle) after a previous dose of any COVID-19 vaccine
- have mastocytosis
- have a child with a history of multisystem inflammatory syndrome (MIS-C), also known as PIMS
What to do if you have a side effect of the COVID-19 vaccine
Talk to your GP if you have any side effects.
If you have a fever (temperature of 38 degrees Celsius or higher) or aches and pains, you can take paracetamol or ibuprofen to help.
If your fever lasts more than 48 hours or if you are still concerned, talk to your GP.
If you are pregnant and you have a fever or aches and pains after vaccination, you can take paracetamol. Do not take ibuprofen or aspirin to treat a fever or aches and pains after vaccination in pregnancy.
You can report any side effects to the Health Products Regulatory Authority (HPRA) at hpra.ie.
Other COVID-19 vaccines
The Comirnaty COVID-19 vaccine is an mRNA vaccine. Some people may not be able to get an mRNA vaccine or chose not to get one. In this case, the Nuvaxovid (Novavax) vaccine is usually recommended.
Nuvaxovid (Novavax) vaccine
The Nuvaxovid (Novavax) vaccine is currently not available in Ireland.
We are trying to get supplies of the vaccine but we do not know if or when it will become available.
You can call HSELive at Freephone 1800 700 700 and ask to be contacted when the Nuvaxovid (Novavax) vaccine becomes available.
Vaccines previously offered
Side effects of vaccines previously offered in Ireland
Reporting side effects
If you think you or your child have had a side effect after getting a vaccine, you can report it to the Health Products Regulatory Authority (HPRA).
Your GP, nurse, pharmacist or a family member can also report the side effect to the HPRA.
COVID-19 vaccine adverse reaction report - hpra.ie
When reporting a side effect
Give as much information as possible. Include the vaccine batch number if you have it. You'll find this on your vaccine record card.
The HPRA cannot provide clinical advice on individual cases. Talk to your doctor or pharmacist about any medical concerns you may have.
Mpox vaccine
If you recently had the mpox vaccine, wait 4 weeks before you get vaccinated with any COVID-19 vaccine. This is a precaution because of the unknown possible risk of myocarditis.
Mpox vaccine
This content was fact checked by vaccine experts working in Ireland.