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Vaccine side effects

You may be concerned that you or your child will have a side effect to a vaccination.

While all vaccines have the potential to cause side effects in some people, the reality is that most tend to be mild and don't last long.

If you have any concerns about an illness or suspected side effect, consult your doctor.

Common vaccine side effects

Common side effects to any vaccine can include:

  • injection site reactions (pain, swelling and redness)
  • mild fever
  • shivering
  • fatigue
  • headache
  • muscle and joint pain

Rare vaccine side effects

A far less common but serious vaccine side effect is an immediate allergic reaction, also known as an anaphylactic reaction. These are dramatic and potentially life-threatening; however, it should be noted that they occur very rarely (fewer than one in a million) and are completely reversible if treated promptly by healthcare staff.

To have a balanced view, potential side effects have to be weighed against the expected benefits of vaccination in preventing the serious complications of disease.

Read more about the benefits and risks of vaccination.

Not all illnesses that occur following vaccination will be a side effect. Because millions of people every year are vaccinated, it's inevitable that some will go on to develop a coincidental infection or illness shortly afterwards.

What to do if your child is unwell after having a vaccination

Most common side effects in babies and young children are at the site where the injection was given and include:

  • swelling
  • redness
  • a small hard lump

These symptoms usually pass within a couple of days and you don’t need to do anything about them.

Children may sometimes develop a fever (high temperature) If this happens, keep your child cool. Make sure they don't wear too many layers of clothes or blankets and give them plenty of cool drinks. You can also give them a dose of infant paracetamol or ibuprofen liquid according to the instructions on the bottle.

Find out about a vaccine's side effects

A Patient Information Leaflet (PIL) is included in the pack of each dose of vaccine which lists its potential side effects.

You can also read vaccine PILs online on the website of the electronic Medicines Compendium (eMC).

Reporting a vaccine side effect

If you, a doctor, nurse or pharmacist suspects that you or your child has had a possible side effect to a vaccine, it can be reported through the Yellow Card Scheme.

The Yellow Card Scheme is run by the Medicines and Healthcare products Regulatory Agency (MHRA) and is designed to pick up unexpected problems or new side effects. If a serious new side effect is identified, the MHRA will follow up the report. It may change the way a vaccine is used, or even take it off the market.

As well as reporting suspected side effects to medicines, you can also report any suspected problems or incidents associated with medical devices, defective and fake healthcare products

The scheme isn’t just for health professionals. Anyone can use the Yellow Card system to report a suspected side effect of a vaccine or medicine.

The Yellow Card scheme

Tell your doctor, nurse or pharmacist about the suspected side effect, and they'll report it for you. Alternatively, you can report it yourself by:

  • using the Yellow Card Scheme online reporting system
  • picking up a Yellow Card form at your GP surgery or local pharmacy. Complete the form and send it to the address provided
  • calling the Yellow Card freephone hotline on 0808 100 3352 (weekdays 10am to 2pm)

Now, read more about the safety of vaccinations, or about the side effects of each vaccine:

Last Updated: 17/02/2022 16:08:37
The information on this page has been adapted by NHS Wales from original content supplied by NHS UK NHS website