Like all medicines, vaccines can cause side effects. Most side effects are mild and short term, and not everyone gets them.
Some of the most common side effects include:
pain, bruising, redness, hardness or swelling where you had the injection
muscle or joint pain
tiredness
loss of appetite
diarrhoea, and
a headache.
The flu vaccine will not give you flu.
If your symptoms seem to get worse or if you are concerned, contact NHS 111 Wales by calling 111 or call your GP surgery. If you get advice from a doctor or nurse, make sure you tell them what vaccines you have had so they can assess you fully.
Rarely, people can have a severe reaction soon after the vaccination, which causes breathing difficulties and may cause them to collapse. This is called an anaphylactic reaction, and it can also happen with other medicines and food. These reactions are extremely rare, affecting less than one in a million people. Staff who give vaccinations are trained to manage these reactions.
People who have an anaphylactic reaction can be successfully treated and usually recover within a few hours.
You should report any side effects of the vaccine through the Yellow Card scheme online, by downloading the Yellow Card app, or by calling 0800 731 6789 (Monday to Friday, 9am to 5pm). Follow this link to the Yellow Card website to report any side effects.
Rydym yn croesawu gohebiaeth a galwadau ffôn yn y Gymraeg neu'r Saesneg. Atebir gohebiaeth Gymraeg yn y Gymraeg, ac ni fydd hyn yn arwain at oedi. Mae’r dudalen hon ar gael yn Gymraeg drwy bwyso’r botwm ar y dde ar frig y dudalen.
We welcome correspondence and telephone calls in Welsh or English. Welsh language correspondence will be replied to in Welsh, and this will not lead to a delay. This page is available in Welsh by clicking ‘Cymraeg’ at the top right of this page.