The MMR vaccine is very safe and most side effects are mild and short-lived.
Because the MMR vaccine combines 3 separate vaccines in 1 injection, each vaccine can cause different side effects that can happen at different times.
There's less chance of side effects after the second dose of MMR than the first.
Common side effects of the MMR vaccine
About a week to 11 days after the MMR injection, some children get a very mild form of measles.
This includes a rash, high temperature, loss of appetite and a general feeling of being unwell for about 2 or 3 days.
About 3 to 4 weeks after having the MMR injection, 1 in 50 children develop a mild form of mumps.
This includes swelling of the glands in the cheek, neck or under the jaw, and lasts for a day or two.
One to 3 weeks after receiving the rubella vaccine component of MMR vaccine, some adult women experience painful, stiff or swollen joints, which can last for around 3 days.
Rare side effects of the MMR vaccine
In rare cases, a child may get a small rash of bruise-like spots about 2 weeks after having the MMR vaccine.
This side effect is linked to the rubella vaccine and is known as idiopathic thrombocytopenic purpura (ITP).
It's been estimated that ITP develops in 1 in every 24,000 doses of the MMR vaccine given.
There's a greater risk of developing ITP from measles or rubella infection than there is from having the vaccine.
ITP usually gets better without treatment but, as with any rash, you should seek advice from your GP as soon as possible.
There's a small chance of having a seizure (fit) 6 to 11 days after having the MMR vaccine.
It sounds alarming, but it's rare and happens in only about 1 in every 1,000 doses.
In fact, MMR-related seizures are less frequent than seizures that occur as a direct result of a measles infection.
Allergic reaction to the MMR vaccine
In extremely rare cases, a child can have a severe allergic reaction (known medically as anaphylaxis) immediately after having the MMR vaccine.
It's an alarming prospect, but if the child is treated quickly, they make a full recovery. Medical staff who give vaccines are trained to deal with allergic reactions.
This NHS leaflet tells you about the common side effects of vaccinations that may occur in babies and children under 5 (PDF, 118.42kb).
Monitoring safety and side effects of the MMR vaccine
The Yellow Card Scheme allows you to report suspected side effects from any medicine you're taking.
It's run by a medicines safety watchdog called the Medicines and Healthcare products Regulatory Agency (MHRA).
Page last reviewed: 13 July 2018
Next review due: 13 July 2021