Like all medicines, the flu vaccine can cause side effects. They're usually mild and normally last only a day or two. It’s normal to experience side effects after a vaccine. It shows the vaccine is teaching your body’s immune system how to protect itself from the disease. But not everyone gets side effects.
These potential side effects are much less serious than flu or complications associated with flu.
Common side effects
Very common side effects in the first day or two may include:
having a painful, heavy feeling and tenderness in the arm where you
had your injection
headache, aches and chills
diarrhoea, nausea and vomiting
mild flu-like symptoms.
fever (temperature 37.8°C or above)
feeling generally unwell
You can rest and take the normal dose of paracetamol (follow the advice in the packaging) to help make yourself feel better.
Phone 111 if:
You're concerned about yourself or anyone else in your household who is unwell following a vaccination.
Fever after the vaccine
It’s quite common to develop a fever (temperature of 37.8°C or above) after a vaccination. This normally happens within 48 hours of the vaccination and usually goes away within 48 hours.
If the fever starts more than 48 hours after the vaccination, or lasts longer than 48 hours, you should seek medical advice as you may have coronavirus or another infection.
More information about vaccine side effects
More information on the possible side effects of the flu vaccine is available in the patient information leaflets: