The NHS recommends painkillers for at-home treatment and to call 111 if symptoms get worse.
The rarest side effects can indicate potentially severe problems and may require medical intervention.
For example, people with a history of allergic reactions may experience anaphylaxis.
Researchers have also recorded cases of blood clotting following vaccine doses, although these are rare.
Blood clots develop on one part of the body and can dislodge, leading them to settle in vital organs such as the brain or lungs.
When they settle in the lungs, they cause a pulmonary embolism.
And when these clots enter the brain, they cause strokes.