What are the side effects of the MMR vaccine?

Millions of doses of the MMR vaccine have been given worldwide for over 35 years. The vaccine has a very good safety record.

Side effects are usually mild and are less common after the second dose.

It is important to remember that side effects of the vaccine are much milder than the serious problems caused by measles, mumps and rubella.

Like all medicines, vaccines can cause side effects. Most of these are mild and don’t last long, and not everyone gets them. The most common side effects should only last a day or two.  

Common or very common side effects

The most common side effects include:  

soreness, redness and swelling or bruising at the site of the injection
fever
rash (including measles-like rash), and
upper respiratory infection.

People can sometimes get a sore arm or thigh where the injection was given. Some may develop a small lump where the needle was put in, and the area around it might also be slightly hot and red. This is normal and may last for several weeks. It does not need any treatment.

The vaccine contains weakened types of live measles, mumps and rubella viruses. Because the viruses are weakened, people who have had the vaccine cannot infect other people. The three different viruses in the vaccine act at different times and may produce the following side effects after the first dose.  

Around six to 10 days after the vaccination, as the measles part of the vaccine starts to work, about one in 10 people may develop a fever. Some develop a measles-like rash and a loss of appetite. Symptoms usually last two to three days. 
About three weeks after the vaccination, people may get mumps-like symptoms (a fever and swollen glands) as the mumps part of the vaccine starts to work. These symptoms have been reported on a few occasions.

Rarely, people can have a severe reaction soon after vaccination, which causes breathing difficulties and may cause them to collapse. This is called an anaphylactic reaction, and it can also happen with other medicines and food. These reactions are extremely rare, affecting less than one in a million people. Staff who give vaccinations are trained to manage these reactions. 

People who have an anaphylactic reaction can be successfully treated and usually recover within a few hours.

You can find reports of all side effects in the patient information leaflet for the vaccine. For more information on side effects, go to the following web pages.

If your, or your child’s, symptoms get worse or if you are concerned, contact NHS 111 Wales by ringing 111, or contact your GP surgery. Calls to NHS 111 Wales are free from landlines and mobile phones.

You should report suspected side effects of vaccines and medicines online at mhra.gov.uk/yellowcard (external site), by downloading the Yellow Card app, or by calling
0800 731 6789 (Monday to Friday, 9am to 5pm). 