Like all medicines, vaccines can cause side effects. This is because they work by triggering a response in your immune system. Most of these side effects are mild and only last a few days, and not everyone gets them.
The most common side effect is a sore arm where you had the injection. Other side effects include fever, feeling tired, general aches, chills or flu-like symptoms, swelling of the arm you had the vaccination in, loss of appetite, irritability and headache. Serious side effects are very rare.
These symptoms normally last less than a week. If your symptoms seem to get worse or if you are concerned, dial 111 to get through to NHS 111 Wales. If you get advice from a doctor or midwife, make sure you tell them about your vaccinations so that they can assess you properly.
You can also report suspected side effects of vaccines and medicines through the Yellow Card scheme. You can do this online by searching Yellow Card scheme, by downloading the Yellow Card app, or by calling 0800 731 6789 (Monday to Friday, 9am to 5pm).