When it comes to vaccination and painkillers (such as paracetamol, or ibuprofen), the key distinction is treating symptoms after versus pre-medicating before.
After the jab: take it if you have symptoms
If you get a sore arm, headache, muscle aches or fever after vaccination, you can take a painkiller or fever reducer as directed to ease it. This doesn't reduce the vaccine's effectiveness and is a reasonable way to manage discomfort.
Before the jab: pre-medicating "just in case" is generally not advised
Taking a painkiller or fever reducer before the jab purely as a precaution, when you have no symptoms, is generally not recommended. Some studies suggest pre-medicating may slightly blunt the body's immune response to the vaccine. So unless your doctor advises otherwise, wait until symptoms appear and then take it as needed.
If you already take painkillers long-term
If you take a painkiller long-term for another condition (such as arthritis), you don't need to stop it on your own for the jab. But tell your doctor what you're taking before vaccination and let them decide.
Medication for children
For children, you must give the correct dose for their age and weight, and use a child-appropriate formulation. If unsure, check with a doctor or pharmacist before giving it.
If you're allergic to a particular painkiller, or have liver, kidney or stomach problems, consult a doctor before taking it.