A combined vaccine against measles, mumps and rubella
MMR vaccine
A single combined vaccine that protects against three infections: measles, mumps and rubella (German measles).
What is MMR vaccine?
The MMR vaccine is a single combined vaccine that protects against three serious infections in one injection: measles, mumps and rubella. It is given as part of the routine UK childhood immunisation schedule and works by helping the immune system learn to fight these viruses, preventing infection rather than treating it. The most important safety point is that it is a live vaccine, so it should be avoided in pregnancy and in people with a significantly weakened immune system. The most common side effects are soreness where the injection is given, a mild fever and sometimes a mild rash. It is important to know the MMR vaccine is not linked to autism. Following the UK immunisation schedule gives the best protection.
Education and reference only. This is a plain-language guide to MMR vaccine — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
The MMR vaccine protects against measles, mumps and rubella (German measles), three infections that can cause serious illness and complications. Measles can lead to severe chest and brain infections, mumps can cause painful swelling and complications, and rubella in pregnancy can seriously harm the unborn baby. The vaccine combines protection against all three in one injection and is given as part of the routine UK childhood immunisation schedule, usually as two doses. It is a live vaccine, meaning it contains weakened forms of the viruses that cannot cause the real diseases in healthy people but teach the immune system to recognise them.
How it works
The MMR vaccine contains weakened (attenuated) forms of the measles, mumps and rubella viruses. These are too weak to cause the actual illnesses in healthy people, but they are enough for the immune system to learn what each virus looks like. If the person later meets the real viruses, their immune system can respond quickly and strongly to prevent infection. Because it trains the immune system before exposure, it is given as part of a planned schedule rather than when someone is ill. Two doses are given to make sure as many people as possible are well protected against all three infections.
Company & origin
Originated / developed by: Various manufacturers.
A combined vaccine used in the UK as part of the UK childhood immunisation schedule to protect against measles, mumps and rubella.
Practical use
How to take MMR vaccine
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Have it as an injection at the ages recommended on the UK childhood immunisation schedule, usually as two doses.
- Make sure both doses are given, as the second dose improves protection against all three infections.
- Tell the nurse if the person is pregnant or has a significantly weakened immune system, as it is a live vaccine.
- Expect possible mild fever or rash about a week or so afterwards, as the immune system responds.
- Be reassured that the MMR vaccine is not linked to autism, which has been thoroughly studied and disproven.
Weighing it up
Advantages & disadvantages of MMR vaccine
Advantages
- Protects against three serious infections, measles, mumps and rubella, in a single injection.
- Offered free within the UK health service as part of the routine childhood schedule.
- Helps protect the wider community, including babies and people who cannot be vaccinated.
Disadvantages
- As a live vaccine, it must be avoided in pregnancy and in significant immunosuppression.
- Can cause a mild fever and sometimes a mild rash about a week later.
- Needs two doses to give the best protection.
Practical use
Good to know
The most important safety point is that MMR is a live vaccine: because it contains weakened viruses, it should not be given in pregnancy, and women are usually advised to avoid becoming pregnant for a short period after having it, and it is generally avoided in people with a significantly weakened immune system, such as those on strong immune-suppressing treatment. For everyone else it is very safe. The most common side effects are soreness where the injection is given, a mild fever, and sometimes a mild measles-like rash or briefly swollen glands a week or so later, as the immune system responds. It is important to know that the MMR vaccine is not linked to autism; this has been thoroughly studied and disproven. Following the UK immunisation schedule, including both doses, gives the best protection for the child and helps protect others who cannot be vaccinated.
Who should not take it / use with caution
- Women who are pregnant should not have it, as it is a live vaccine; pregnancy should usually be avoided for a short time after.
- It is generally avoided in people with a significantly weakened immune system, such as those on strong immune-suppressing treatment.
- People who have had a serious allergic reaction to a previous dose or an ingredient should not have it; it is usually delayed during a feverish illness.
Monitoring
- A short wait after the injection in case of a rare immediate allergic reaction.
- Checking the schedule so the second dose is given on time.
- No routine blood tests are needed for healthy people having the vaccine.
Side effects
- Soreness, redness or swelling where the injection is given.
- A mild fever, and sometimes a mild measles-like rash or briefly swollen glands a week or so later.
- Feeling generally off-colour for a day or two, which soon settles.
Key interactions
- It can usually be given at the same time as other routine vaccines, as advised by your nurse.
- Tell the nurse about any medicines or treatments that weaken the immune system, as it is a live vaccine.
- Recent treatment with blood products may affect timing, so let the nurse know.
Available as: A powder made up into a suspension for injection, usually given into the muscle or under the skin.
Answers
MMR vaccine: frequently asked questions
What does the MMR vaccine protect against?
It protects against three infections in one injection: measles, mumps and rubella (German measles), all of which can cause serious illness.
Is the MMR vaccine linked to autism?
No. The MMR vaccine is not linked to autism; this has been thoroughly studied in very large numbers of children and disproven.
Why must it be avoided in pregnancy?
MMR is a live vaccine containing weakened viruses, so it is not given in pregnancy, and becoming pregnant is usually avoided for a short time after having it.
Why might there be a fever or rash afterwards?
A mild fever and sometimes a mild rash about a week later are normal signs that the immune system is responding to the weakened viruses; they soon settle.
When is it given?
It is offered free within the UK health service as part of the routine childhood schedule, usually as two doses, so it is best to follow the UK immunisation schedule.
The wider class
About Vaccine (measles, mumps, rubella)
MMR vaccine belongs to the vaccine (measles, mumps, rubella) class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
Browse by body system
Authoritative sources
- BNF
- NICE CKS
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