MMR is a safe and effective combined vaccine that protects against three separate illnesses - measles, mumps and rubella (German measles) - in a single injection. The full course of MMR vaccination requires two doses.
They can also lead to complications in pregnancy that affect the unborn baby, and can lead to miscarriage.
Since the MMR vaccine was introduced in 1988, it's rare for children in the UK to develop these serious conditions. However, outbreaks happen and there have been cases of measles in recent years, so it's important to ensure that you and your children are up-to-date with the MMR vaccination.
MMR vaccine for babies and preschoolers
The MMR vaccine is given on the NHS as a single injection to babies as part of their routine vaccination schedule, usually within a month of their first birthday.
They will then have a second injection of the vaccine before starting school, usually at three years and four months.
The MMR vaccine can sometimes be given to babies from six months of age if they may have been exposed to the measles virus, or during a measles outbreak.
Babies under six months old are not routinely given the MMR vaccine. This is because the antibodies to measles, mumps and rubella passed from mother to baby at the time of birth are retained and can work against the vaccine, meaning that the vaccine is not usually effective.
These maternal antibodies decline with age and are almost all gone by the time MMR is normally given - around the age of one.
MMR vaccination is recommended for six- to nine-month-old babies if they are at high risk of becoming infected in certain circumstances, such as during a measles outbreak.
However, these children may not have enough protection from this early dose, so they will still need the standard MMR doses at 12-13 months and 40 months of age.
The MMR vaccine is given as a single injection into the muscle of the thigh or upper arm.
Watch these healthtalk.org videos where parents weigh up the risks and benefits of MMR vaccination.
MMR for older children
Children up to the age of 18 who missed, or only partially completed, their earlier MMR vaccination can have a "catch-up" MMR vaccination on the NHS.
If you know or suspect your child hasn't been fully immunised, arrange with your GP for them to have a catch-up MMR vaccination.
MMR for women planning pregnancy
If you're thinking about getting pregnant, it's a good idea to check that you are fully protected against measles, mumps and rubella. Rubella infection in pregnancy can lead to serious birth defects and miscarriage.
If you're not sure whether you've had two doses of the MMR vaccine, ask your GP practice to check.
If you haven't had both doses or there's no record available, you can have the vaccinations at your GP practice.
You should avoid becoming pregnant for one month after having MMR vaccination.
Be aware that the MMR vaccine is not suitable for women who are already pregnant.
MMR for non-immune adults
The MMR vaccine can also be given on the NHS to adults who may need it, including people born from 1970-79 who may have only been vaccinated against measles, as well as those born from 1980-90 who may not be protected against mumps.
Check with your GP if you're not sure whether you've had the MMR vaccine. If in doubt, go ahead and have it. Even if you've had it before, it won't harm you to have a second, or even third, course of the vaccination.
Read more about when the MMR vaccine is needed.
Read the NHS leaflet: measles not just a kids' problem (PDF, 868kb)
How the MMR vaccine works
The MMR vaccine contains weakened versions of live measles, mumps and rubella viruses. The vaccine works by triggering the immune system to produce antibodies against measles, mumps and rubella.
If you or your child then comes into contact with one of the diseases, the immune system will recognise it and immediately produce the antibodies needed to fight it.
It's not possible for people who have recently had the MMR vaccine to infect other people.
The MMR vaccine given in the UK is known under the brand names Priorix, or M-M-RVAXPRO.
Does the MMR vaccine cause autism?
There has been some controversy about whether the MMR vaccine might cause autism, following a 1998 study by Dr Andrew Wakefield.
In his paper, published in The Lancet, Dr Wakefield claimed there is a link between the MMR vaccine and autism or bowel disease.
However, Andrew Wakefield's work has since been completely discredited and he has been struck off as a doctor in the UK. Subsequent studies in the last eight years have found no link between the MMR vaccine and autism or bowel disease.
Watch healthtalk.org videos where parents discuss their worries about the MMR vaccine.
Single measles, mumps and rubella vaccines
Single vaccines are not available on the NHS in the UK because there is a risk that fewer children would receive all the necessary injections, increasing the levels of measles, mumps and rubella in the country.
The delay in having six separate injections would also put more children at risk of developing the conditions, as well as increasing the amount of work and inconvenience for parents and those administering the vaccines.
Side effects of the MMR vaccine
As there are three separate vaccines within a single injection, different side effects can occur at different times. The side effects of the MMR vaccine are usually mild. It's important to remember that they're milder than the potential complications of measles, mumps and rubella.
Side effects include:
- developing a mild form of measles that lasts for two to three days - this is not infectious
- developing a mild form of mumps that lasts for a day or two - this is not infectious
In rare cases, a small rash of bruise-like spots may appear a few weeks after the injection. See your GP if you notice this kind of rash, or if you have any concerns about your child's symptoms after having the MMR jab.
Find out how the MMR jab is given.
This NHS leaflet tells you about the common vaccination reactions in babies and young children up to the age of five years.
Read the answers to other common questions about the MMR vaccine.
Article provided by NHS Choices