Side effects and safety of COVID-19 vaccines

Very common side effects may affect more than 1 in 10 people.

These include:

• feeling tired
• tenderness or swelling where you had the vaccine
• headache
• swollen lymph glands under the arm where you had the vaccine
• muscle pain
• joint pain
• nausea or vomiting
• fever (temperature of 38 degrees Celsius or above)
• chills

Common side effects may affect up to 1 in 10 people.

These include:

• diarrhoea
• rash
• rash, redness, or hives where you had the injection
• reaction a few days after where you had the injection

Uncommon side effects may affect up to 1 in 100 people.

These include:

• itchiness where you had the vaccine injection
• dizziness

Rare side effects may affect up to 1 in 1,000 people.

These include:

• Bell's Palsy - a weakness in the muscles on one side of your face (that may cause it to droop temporarily)
• swelling of your face - this can happen in people who have had facial fillers
• reduced sense of touch or sensation in a part of the body

Very rare side effects may affect up to 1 in 10,000 people.

These include:

• myocarditis
• pericarditis

Myocarditis and pericarditis are inflammatory heart conditions.

The risk of these very rare conditions is higher in younger men.

These conditions are more likely to occur after the second dose and mostly happen within 14 days of getting the vaccine.

2 European studies have estimated the risk of myocarditis, after the second dose of the vaccine as:

• 1 additional case for every 7,600 men aged 12 to 29 (within 7 days)
• 1 additional case for every 5,320 men aged 16 to 24 (within 28 days)

First and second booster doses of mRNA vaccines have not shown any unexpected short-term safety concerns. The risk appears to be comparatively lower following a first booster dose. Data on second booster doses is more limited, but preliminary experience from Israel has not shown any new safety concerns.

Symptoms of myocarditis and pericarditis

Get urgent medical help if you get any of these symptoms in the weeks after the Moderna COVID-19 vaccine:

• breathlessness
• palpitations (a forceful heartbeat that may be irregular)
• chest pain

Extremely rare side effects

We do not know yet how many people are affected by extremely rare side effects. There is not enough data available at this time.

These include:

• erythema multiforme - a skin reaction that causes red spots or patches on the skin. It may look like a target or 'bulls-eye' with a dark red centre surrounded by paler red ring
• hypersensitivity reactions (unwanted increased response from the immune system)
• severe allergic reaction (anaphylaxis)
• flare-ups of capillary leak syndrome
• extensive swelling of the vaccinated limb

Symptoms of capillary leak syndrome

Capillary leak syndrome causes fluid to leak from small blood vessels. There is a possible risk of flare-ups in people with a history of capillary leak syndrome. Even though the risk of the condition is extremely low, you should know the signs to watch for.

Get urgent medical help if you get any of these symptoms after the Moderna vaccine:

• rapid swelling of the limbs (arms and legs)
• sudden weight gain

You may also feel faint due to low blood pressure.

People usually reported capillary leak syndrome within the first few days of getting this vaccine. Watch out for these symptoms in the days after your vaccination.

The Moderna COVID-19 vaccine is only used in adults aged 30 and over in Ireland.

If you are under 30 and had the Moderna vaccine, you should get the Pfizer/BioNTech vaccine for any other doses you need.

Moderna is not recommended if you have had a severe allergic reaction to:

• any of the ingredients in this vaccine - including polyethylene glycol or PEG
• Trometamol - an ingredient in contrast dyes used for MRI scans

You should also not get this vaccine if you:

• have been told by a doctor that you should not get this vaccine or the Pfizer/BioNTech COVID-19 vaccine - they are both mRNA vaccines

Talk to your doctor before getting this vaccine if you:

• have had a severe allergic reaction (anaphylaxis) in the past, including to any other vaccine or medication
• have a history of capillary leak syndrome
• had myocarditis or pericarditis (inflammation of the heart muscle) after a previous dose of any COVID-19 vaccine

Ingredients of Moderna COVID-19 vaccine

The Moderna 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.

Spikevax (Moderna) COVID-19 vaccine - ema.europa.eu

Very common side effects may affect more than 1 in 10 people.

These include:

• feeling tired
• feeling generally unwell
• headache
• nausea or vomiting
• muscle pain
• joint pain
• tenderness or pain in your arm where you had the vaccine injection

Common side effects may affect up to 1 in 10 people.

These include:

• fever (temperature of 38 degrees Celsius or above)
• chills
• pain in extremities (arm, hand, leg or foot)
• redness or swelling where the vaccine was given

Uncommon side effects may affect up to 1 in 100 people.

These include:

• swelling of the lymph glands
• high blood pressure lasting for a few days after vaccination
• a rash
• redness of the skin
• general itchiness
• itchiness where the vaccine was given
• hives

Some side effects are seen more often after the second dose.

We do not know yet how many people are affected by extremely rare side effects. There is not enough data available at this time.

Extremely rare side effects include:

• tingling or prickling sensation
• loss of sensation in some parts of the body
• myocarditis and pericarditis

Symptoms of myocarditis and pericarditis 

Myocarditis and pericarditis are inflammatory conditions of the heart. Even though the risk of these conditions is very low, you should know the signs to look for. 

These conditions can develop a few days after vaccination. They have mostly been seen within 14 days.

Get medical help if you get any of these symptoms after you get this vaccine:

• breathlessness
• palpitations (a forceful heartbeat that may be irregular)
• chest pain

Most people aged 12 or older can safely get the Novavax COVID-19 vaccine Nuvaxovid.

But this vaccine is not recommended if you have had a severe allergic reaction to:

• a previous dose of the vaccine
• any of the ingredients in the vaccine (including polysorbate 80)

You can read more about the vaccine ingredients on the European Medicine Agency's website.

Talk to your doctor before getting a COVID-19 vaccine if you:

• have had a severe allergic reaction (anaphylaxis) in the past, including to any other vaccine or medication
• had myocarditis or pericarditis (inflammation of the heart muscle) after a previous dose of any COVID-19 vaccine

Nuvaxovid COVID-19 vaccine - ema.europa.eu

Very common side effects may affect more than 1 in 10 people.

These include:

• pain where you had the injection
• headache
• muscle pain
• joint pain
• feeling generally unwell
• chills

Common side effects may affect up to 1 in 10 people.

These include:

• redness or swelling where you had the injection
• fever (temperature of 38 degrees Celsius or above)
• feeling tired
• nausea
• diarrhoea

Uncommon side effects may affect up to 1 in 100 people.

These include:

• itchiness where you had the injection
• bruising where you had the injection
• warmth where you had the injection
• swollen lymph glands

You should not get the Vidprevtyn Beta COVID-19 vaccine if you have had a severe allergic reaction (anaphylaxis) to:

• a previous dose of this vaccine
• any of the ingredients in the vaccine (including polysorbate 20 or octylphenol ethoxylate)

Read more about the vaccine ingredients on the European Medicine Agency's website.

Vidprevtyn Beta COVID-19 vaccine - ema.europa.eu

Talk to your doctor before getting this COVID-19 vaccine if you:

• had a severe allergic reaction (anaphylaxis) in the past, including to any other vaccine or medication