COVID-19: Vaccine side effects and reactions

Find out the side effects, the reported adverse events and allergic reactions to the Pfizer vaccine.

Last updated: 24 November 2021

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This page is about the Pfizer vaccine. For information about AstraZeneca, see AstraZeneca vaccines.

Known side effects

Like all medicines, the vaccine may cause side effects in some people. Most side effects are mild and don’t last long – they're more common after the second dose.

They won’t stop you from having the second dose or going about your daily life. Some side effects may temporarily affect your ability to drive or use machinery.

Common side effects

In the clinical trials, common side effects were reported in every 1 in 10 to 1 in 100 people. These include:

  • pain or swelling at the injection site
  • feeling tired or fatigued
  • headache
  • muscle aches
  • chills
  • joint pain
  • fever
  • redness at the injection site
  • nausea

Uncommon side effects

In the clinical trials, uncommon side effects were reported in every 1 in 100 to 1 in 1,000 people. These include:

  • enlarged lymph nodes
  • feeling unwell
  • insomnia

Rare side effects

Temporary one-sided facial drooping has been reported as a rare side effect, affecting every 1 in 1,000 to 1 in 10,000 people in the clinical trials.


Myocarditis is an inflammation of the heart muscle wall and is another known rare side effect of vaccination with the Pfizer COVID-19 vaccine.

Symptoms of myocarditis can include:

  • new onset chest pain
  • shortness of breath
  • abnormal/racing heartbeat.

It’s important that anyone who experiences these symptoms in the first few days after vaccination seeks medical attention promptly.

There are many other possible causes of myocarditis, and the most common cause is a viral infection, including COVID-19.

The risk of developing myocarditis is higher if you become infected with COVID-19 than as a reaction to the Pfizer vaccine.

More about how the Pfizer vaccine was developed and approved

Allergic reactions

Serious allergic reactions do happen but are extremely rare. They usually show soon after you’ve had your vaccine, which is why you need to wait at least 15 minutes. If you do have a serious allergic reaction, vaccinators are trained to manage these.

If you’ve had an allergic reaction to any vaccine or injection in the past, talk to your vaccinator.

When you’re likely to experience a side effect

Most side effects show within a day or two after being vaccinated.

What you may feel What can help When this could start

Pain at the injection site, a headache and feeling tired and fatigued. These are the most commonly reported side effects.

Place a cold, wet cloth, or ice pack on the injection site for a short time.

Do not rub or massage the injection site.

Within 6 to 24 hours

Muscle aches, feeling generally unwell, chills, fever, joint pain and nausea may also occur.

Rest and drink plenty of fluids

Paracetamol or ibuprofen can be taken, follow the manufacturer’s instructions.

Seek advice from your health professional if your symptoms worsen.

Within 6 to 48 hours

New onset chest pain, racing heart, or shortness of breath Speak to your health professional promptly if you develop any of these symptoms. Within 14 days

If you’re concerned about how you’re feeling

If you’re unsure about your symptoms or if they get worse, call Healthline:

Phone 0800 358 5453

If you’re concerned about your safety, call 111. Tell them you’ve had a COVID-19 vaccination so they can assess you properly.

Reported side effects in New Zealand

Adverse events following immunisation (AEFI) for the COVID-19 vaccine are reported to the Centre for Adverse Reactions Monitoring (CARM). We commonly know these as side effects.

Any side effects reported are suspected by the reporter to be caused by the vaccine. It doesn’t always mean the vaccine did cause the side effect.

Centre for Adverse Reactions Monitoring (CARM)

Report your side effects to CARM

Medsafe closely monitors and releases a safety report showing this data each week. This shows the most common side effects that people in New Zealand experience after getting the COVID-19 vaccine.

Latest safety report from Medsafe

Medsafe publishes weekly reports summarising the number and type of adverse events following immunisation (AEFI) reported with COVID-19 vaccines. Please note there is a time lag between receipt of AEFI reports and publication of the weekly report.

Timeframe: 20 February to 6 November 2021
COVID-19 vaccine administered: Pfizer/BioNTech (Comirnaty)
Total doses given: 7,045,721

Number of reports received on adverse events following immunisation (AEFI)

This shows the number of reports, not the number of people who experienced an adverse event. One person may report on more than one symptom.

  • Total reports received: 35,700
  • Total reports that were serious: 1,290
  • Total reports that were not serious: 34,410

The most reported adverse events

The top 10 reported adverse events were:

  • Dizziness: 11,108 reports
  • Headache: 10,644 reports
  • Lethargy: 8,608 reports
  • Pain at the injection site: 8,526 reports
  • Nausea: 7,605 reports
  • Chest discomfort: 5,381 reports
  • Influenza-like illness: 4,710 reports
  • Fever: 4,675 reports
  • Numbness: 3,270 reports
  • Fainting: 3,254 reports

Serious adverse cases reported

Medsafe publishes detailed safety information about the Pfizer vaccine and provides weekly information on serious adverse events following immunisation with COVID-19 vaccines.

See details in the full reports

View the full reports

For the full reports, including definitions:

Safety report 36 – 6 November 2021
Safety report 35 – 30 October 2021
Safety report 34 – 23 October 2021
Safety report 33 – 16 October 2021
Safety report 32 – 9 October 2021
Safety report 31 – 2 October 2021
Safety report 30 – 25 September 2021
Safety report 29 – 18 September 2021
Safety report 28 – 11 September 2021
Safety report 27 – 4 September 2021
Safety report 26 – 28 August 2021
Safety report 25 – 21 August 2021
Safety report 24 – 14 August 2021
Safety report 23 – 7 August 2021
Safety report 22 – 31 July 2021
Safety report 21 – 24 July 2021
Safety report 20 – 17 July 2021
Safety report 19 – 10 July 2021
Safety report 18 – 3 July 2021
Safety report 17 – 26 June 2021
Safety report 16 – 19 June 2021
Safety report 15 – 12 June 2021
Safety report 14 – 5 June 2021
Safety report 13 – 29 May 2021
Safety report 12 – 22 May 2021
Safety report 11 – 15 May 2021
Safety report 10 – 8 May 2021
Safety report 9 – 1 May 2021
Safety report 8 – 24 April 2021
Safety report 7 – 17 April 2021
Safety report 6 – 10 April 2021
Safety report 5 – 3 April 2021
Safety report 4 – 27 March 2021
Safety report 3 – 20 March 2021
Safety report 2 – 13 March 2021
Safety report 1 – 6 March 2021

Medsafe is New Zealand’s medical regulatory body which administers the Medicines Act 1981 and Medicines Regulations 1984.

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