Side effects of the MMR vaccine

There are some mild side effects from the MMR vaccine, and these are explained below.

It is important to bear in mind that the risk of serious side effects from the actual diseases far outweigh the risk of your child suffering any of the side effects from the immunisation.

If you go to the MMR and risk section of the library, you can compare the risks of the vaccine against the risks of the diseases, or for more information on measles, mumps and rubella infections, go to The diseases.

What are the side effects of MMR?

MMR contains three separate vaccines in one injection. Each vaccine has different side effects at different times:

• About a week to 10 days after the MMR immunisation some children become feverish and they may develop a measles-like rash and go off their food. This is because the measles part of the vaccine is starting to work.
• About three to four weeks after the injection a child might occasionally get a mild form of mumps as the mumps part of MMR kicks in.
• In the six weeks after MMR your child may, very rarely, get a rash of small bruise-like spots which may be caused by the measles or rubella parts of the immunisation. This usually gets better on its own.
• Very rarely, children can have severe allergic reactions straight after any immunisation (about 1 in 100,000 immunisations for MMR). If the child is treated quickly, he or she will recover fully. People giving immunisations are trained to deal with allergic reactions.
• Idiopathic thrombocytopenic purpura (ITP), a bleeding disorder, has long been a recognised side-effect of live viral vaccines such as measles, rubella and MMR. A study by researchers from the Public Health Laboratory Service (published in Archives of Diseases in Childhood, February 2001) confirms earlier estimates that the rate of ITP after MMR is around 1 in 22,300. It is important to remember that the rate of ITP after natural viral illness is much higher (at about 1 in 3,000 for rubella and 1 in 6,000 for measles) and that the severity of illness in non-vaccine related ITP cases is much greater. Therefore MMR offers protection against this higher risk of ITP due to the natural disease, as well as the other known serious complications of measles, mumps and rubella.

• MMR and risk
• The diseases