Influenza vaccine

Influenza vaccine helps to protect against seasonal flu.

In adults, the vaccine is injected into a muscle. A nasal spray containing the vaccine is available for school-aged children.

The most common side-effects are mild fever (raised temperature), feeling tired, and head/muscle aches. You may experience tenderness at the site of injection after a flu jab. Children having the nasal spray may develop a blocked or runny nose.

Type of medicineInfluenza (flu) vaccine
Used forProtection against flu
Also calledAgrippal®; Enzira®; Fluarix®; Fluenz®; Fluvirin®; Imuvac®; Influvac®; Intanza®
Available asInjection and nasal spray

Influenza is an illness caused by the flu virus. There are different strains of flu virus. Each winter a different strain of the flu virus causes an outbreak which affects many people. This is called seasonal flu. Flu is passed from person to person through droplets created when someone with the infection sneezes or coughs.

Immunisation against seasonal influenza (the flu jab) is offered every year to people at risk of developing serious complications from flu. The vaccine greatly reduces the chance of getting seasonal flu, and lasts for one year. It is normally given in October or November each year.

In the UK, the Department of Health (DH) advises who should be immunised. The aim is to protect people who are more likely to develop complications from flu.

Since September 2015, all school-aged children in the UK are offered the flu vaccine each year, either at the doctor's surgery or at school. Children are given a different vaccine to adults. It is called Fluenz® Tetra and is given by nasal spray. It contains a live but weakened form of the flu virus. It will not cause flu in a healthy child.

Before you/your child are given influenza vaccine, make sure your doctor knows:

  • If you/they have been unwell recently, or if you/they have a high temperature.
  • If you/they have previously had an allergic reaction to a flu jab or to any other medicine.
  • If you/they have a severe allergy to eggs.
  • If you/they have a weakened immune system. This may be a result of an illness or taking medicines.
  • If the vaccine is for a child who has close contact with someone who has a poorly working immune system.
  • If you are pregnant or breast-feeding. Even if you are otherwise healthy it is now recommended that all pregnant women receive the flu jab.
  • If you have a condition that makes you bleed more than is normal, such as haemophilia.
  • If you/they are taking any other medicines. This includes any medicines you/they are taking which are available to buy without a prescription, as well as herbal and complementary medicines.
  • Before you/your child are given the vaccine, ask to read the manufacturer's printed information leaflet. The manufacturer's leaflet will give you more information about influenza vaccine and will tell you about any side-effects from having it. If you have any questions about the vaccine, ask your doctor or nurse for advice.
  • Adults will be given one dose of the vaccine (each year). It may be given at the same time as some other vaccines, but it will be given as a separate injection.
  • In adults the vaccine is given by injection into a muscle. If you have a condition that makes you bleed more easily than normal, it may be given as an injection underneath your skin.
  • Children will be given one spray of vaccine (brand Fluenz® Tetra) into both nostrils. A repeat dose will be given four weeks later if it is the first time that they have had the vaccine.
  • If you/your child have a high temperature or if you/they are acutely unwell at the time of the scheduled immunisation, your doctor or nurse may recommend delaying giving the vaccine. A minor illness (such as a cough, cold or snuffles) will not interfere with the vaccine. If a delay is advised, you will be given an alternative appointment for the vaccination to be given.
  • Under no circumstances give aspirin to a child who has received influenza vaccine.

Along with their useful effects, vaccines like most medicines can cause unwanted side-effects, although not everyone experiences them. Influenza immunisation usually causes no problems, but the table below contains some of the side-effects which may occur. You will find a full list in the manufacturer's information leaflet supplied with the vaccine. Speak with a doctor or nurse if any of the following side-effects continue or become troublesome.

Common influenza vaccine side-effectsWhat can I do if I experience this?
Mild soreness, swelling, or redness around the site of the injectionThis should soon pass
Mild fever (raised temperature), loss of appetite, feeling tired or weakThis soon settles
Muscle ache, headacheIf troublesome, ask your pharmacist to recommend a suitable painkiller
Blocked or runny nose (in children)This soon settles

You will normally be asked by the doctor or nurse to wait several minutes after the immunisation to make sure that you do not react badly to the vaccine. Although allergic reactions are extremely rare, you should seek urgent medical advice if you become breathless, or if any swelling or a rash develops within a few days of the immunisation.

If you experience any other symptoms which you think may be due to the vaccine, speak with your doctor or pharmacist. 

If you are having an operation or any dental treatment, tell the person carrying out the treatment which medicines you are taking.

If you buy any medicines, check with a pharmacist that they are suitable to take with your other medicines.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

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Further reading & references

Current Version:
Mr Michael Stewart
Peer Reviewer:
Dr John Cox
Document ID:
28762 (v2)
Last Checked:
11 January 2017
Next Review:
11 January 2020
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The information on this page is written and peer reviewed by qualified clinicians.

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