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What to expect after your COVID-19 vaccination

The COVID-19 vaccine you have received has been approved as safe and effective by the
independent Medicines and Healthcare products Regulatory Agency (MHRA).
Following detailed large studies of safety and effectiveness, the MHRA has approved several
different types of COVID-19 vaccines for use in the UK.
Each vaccine has been given to millions of people in several different countries and shown to be safe and effective. The MHRA continues to review the safety of vaccines in use based on all side effects reported by healthcare professionals and the public.

Will I experience any side effects?

Like all medicines, vaccines can cause side effects. This is because vaccines work by triggering a response in your immune system. These are usually mild and only last a few days, and not everyone gets them. 

Very common side effects include:

• having a painful, heavy feeling and tenderness in the arm where you had your injection for several days after the vaccine
• feeling tired
• a headache
• general aches, chills, or flu like symptoms.
If your arm is particularly sore, you may find heavy lifting difficult. If you feel unwell or very tired you should rest and avoid operating machinery or driving.
An uncommon side effect is swollen glands in the armpit or neck on the same side as you had your vaccination. This can last for about 10 days, but if it lasts longer speak to your doctor. If you are due to have a mammogram in the few weeks after the vaccine, then you should mention this when you attend.
A mild fever may occur for two or three days after vaccination but a high temperature is unusual and may indicate you have COVID-19 or another infection. You can take the normal dose of paracetamol (follow the advice in the packaging) and rest to help you feel better. Do not exceed the normal dose of paracetamol.
These symptoms normally last less than a week. If your symptoms seem to get worse or if you are concerned, call NHS 111. If you do seek advice from a doctor or nurse, make sure you tell them about your vaccination (show them the vaccination card) so that they can assess you properly. You can also report any suspected side effects of vaccines and medicines online at: or via the Yellow Card app.

Are there other more serious side effects?

There have been reports of an extremely rare condition involving blood clots and unusual
bleeding after vaccination with the AstraZeneca and Janssen vaccines. This is being carefully reviewed but the risk factors for this condition are not yet clear.
The Joint Committee on Vaccination and Immunisation (JCVI) advises there is a much lower rate of blood clots and unusual bleeding with further doses. Because of the high risk of complications and death from COVID-19, the MHRA, the World Health Organization and the European Medicines Agency have concluded that the balance is very much in favour of vaccination for the vast majority of adults.

If you experience any of the following from around 4 days to 4 weeks after vaccination, you should seek medical advice urgently:

  • a new, severe headache which is not helped by usual painkillers or is getting worse
  • an unusual headache which seems to get worse when lying down or bending over or may be accompanied by:
    • blurred vision, nausea and vomiting
    • difficulty with your speech
    • weakness, drowsiness or seizures
  • new, unexplained pinprick bruising or bleeding
  • shortness of breath, chest pain, leg swelling or persistent abdominal pain

Worldwide, rare cases of inflammation of the heart called myocarditis or pericarditis have been reported after COVID-19 vaccines. These cases have been seen mostly in younger men within several days after vaccination. Most of these people recovered and felt better following rest and simple treatments.

You should seek medical advice urgently if you experience:

  • chest pain
  • shortness of breath
  • feelings of having a fast-beating, fluttering or pounding heart.

    What should I do if I am unwell on the day of my next appointment?

    If you are unwell with a fever, it is better to wait until you have recovered to have your vaccine. You should also not attend a vaccine appointment if you are self-isolating, or waiting for a COVID-19 test or result. Ideally you should wait at least 4 weeks after having a positive COVID-19 test before having your vaccination. Call to rearrange your appointment as soon as possible.

    Will the vaccine protect me?

    The COVID-19 vaccination will reduce the chance of you suffering from COVID-19
    disease. It will take a few weeks for your body to build up protection from the vaccine. Like
    all medicines, no vaccine is 100% effective so you should continue to take the recommended precautions such as social distancing, hand hygiene and face masks to avoid infection. Some people may still get COVID-19 after having a vaccination, but this should be less severe.

    Can I give COVID-19 to anyone, after I have had the vaccine?

    The vaccine cannot give you COVID-19 infection. It will reduce your chance of becoming seriously ill. The vaccines reduce the risk of passing on the virus, but do not completely prevent it. So, it is still important to follow the guidance in your local area to protect those around you. Information can be found at:

    More Information

    You can find out more information about COVID-19 vaccines, including their contents and possible side effects at:
    Further information and patient leaflets can be found at:

    You can report suspected side effects online at: or
    by downloading the Yellow Card app. 

    To find out how the NHS uses your information, visit:
    For other formats of this leaflet visit:


    Version 6 December 2021