Measles, Mumps, Rubella (MMR) Vaccine Safety

Key points

You can protect against measles, mumps, and rubella with vaccination.

Overview

Measles causes fever, rash, cough, runny nose, and red, watery eyes. Complications can include ear infection, diarrhea, pneumonia, brain damage, and death.

Mumps causes fever, headache, muscle aches, tiredness, loss of appetite, and swollen salivary glands. Complications can include swelling of the testicles or ovaries, deafness, inflammation of the brain and/or tissue covering the brain and spinal cord (encephalitis/meningitis) and, rarely, death.

Rubella, causes fever, sore throat, rash, headache, and red, itchy eyes. If a woman gets rubella while she is pregnant, she could have a miscarriage, or her baby could be born with serious birth defects.

Due to high vaccination rates, outbreaks of measles, mumps, and rubella in the U.S. are not as common as they were before the vaccine began being used. However, these diseases still appear in the U.S. and people who decide not to vaccinate their children because of religious or personal beliefs put their children and others at risk for getting these diseases.

Available vaccines & manufacturer package inserts

  • The FDA approved M-M-R II in 1971 for use in people 12 months of age and older.
  • The FDA approved PRIORIX in 2022 for use in people 12 months of age and older.

The measles, mumps, rubella, and varicella (MMRV) vaccine also protects against these diseases.

Keep Reading: Vaccine Information Statement

Common side effects

  • Sore arm from the shot.
  • Fever.
  • Mild rash.
  • Temporary pain and stiffness in the joints, mostly in teenage or adult women who did not already have immunity to the rubella component of the vaccine.

Some people may experience swelling in the cheeks or neck. MMR vaccine rarely causes a temporary low platelet count, which can cause a bleeding disorder that usually goes away without treatment and is not life threatening.

Vaccines, like any medicine, can have side effects. Most people who get MMR vaccine do not have any serious problems with it. Getting MMR vaccine is much safer than getting measles, mumps, or rubella.

When to call 911‎

Severe allergic reactions following vaccination are rare, but can be life threatening. If someone experiences symptoms of a severe allergic reaction, which can include hives, swelling of the face and throat, difficulty breathing, a fast heartbeat, dizziness, and weakness.

MMR vaccine has been linked with a very small risk of febrile seizures. Febrile seizures following MMR vaccination are rare and are not associated with any long-term effects. Because the risk of febrile seizures increases as infants get older, it is recommended that they get vaccinated as soon as recommended.

Extremely rarely, a person may have a serious allergic reaction to MMR vaccine. Anyone who has ever had a life-threatening allergic reaction to the antibiotic neomycin, or any other component of MMR vaccine, should not get the vaccine.

Report possible adverse events to VAERS‎‎

The Vaccine Adverse Event Reporting System (VAERS) is an early warning system, co-managed by CDC and FDA, that monitors for potential vaccine safety problems. Healthcare providers and vaccine manufacturers are required by law to report certain adverse events (any side effect or health problem after vaccination that is concerning to you, even if you are not sure if the vaccine caused the event) following vaccination to VAERS; patients and caregivers can also submit reports.
Submitting a Vaccine Adverse Event Reporting System (VAERS) Report and Using VAERS Data

A closer look at the safety data

  • Two studies indicate that for every 10,000 children who get their first MMR and varicella vaccines as separate shots when they are ages 12-23 months, about four will have a febrile seizure during the 7-10 days following vaccination. Children of the same age who get the combined measles, mumps, rubella and varicella (MMRV) vaccine as their first vaccine against these diseases are twice as likely to have a febrile seizure during the same time period.12
  • Studies have shown that for children younger than 7 years old, there is a very small increased risk of febrile seizures approximately 6 to 14 days after MMR vaccination; this happens in about 1 in 3,000 to 4,000 children.
  • Joint pain is associated with the rubella portion of MMR vaccine among people who do not have immunity to rubella. Joint pain and temporary arthritis happen more often after MMR vaccination in adults than in children. Women also experience this reaction more often than men. Joint pain or stiffness occurs in up to 1 in 4 of females past puberty who were not previously immune to rubella; their symptoms generally begin 1 to 3 weeks after vaccination, are usually mild and last about 2 days. These symptoms rarely come back.
  • Immune thrombocytopenic purpura (ITP) is a disorder that decreases the body's ability to stop bleeding. It can happen after both natural measles infection as well as after getting the MMR vaccine. However, it is usually not life threating. Treatment may include blood transfusion and medications. The risk of ITP has been shown to be increased in the six weeks following an MMR vaccination, with one study estimating 1 case per 40,000 vaccinated children.
  • Measles inclusion body encephalitis, or severe brain swelling caused by the measles virus, is a complication of getting infected with the wild-type measles virus. While rare, this disorder almost always happens in patients with weakened immune systems. The illness usually develops within 1 year after initial measles infection and has a high death rate. There have been three published reports of this complication happening to people who are vaccinated. In these cases, encephalitis developed between 4 and 9 months after MMR vaccination. In one case, the measles vaccine strain was identified as the cause.

Safety studies

Adverse events

  • The most common adverse events following the MMR vaccine are pain where the vaccine is given, fever, a mild rash, and swollen glands in the cheeks or neck.
  • Studies have shown a small increased risk of febrile seizures occurs among children who are younger than 7 years old approximately 8-14 days after vaccination at a rate of one for every 3,000-4,000 children vaccinated with MMR vaccine. This is compared to children not vaccinated during the preceding 30 days.

Separating MMR vaccine shots

No published scientific evidence shows any benefit in separating the combination MMR vaccine into three individual shots.

Outbreaks

Measles outbreaks can occur in communities with a high number of unvaccinated people. Maintaining high overall MMR vaccination rates is needed to continue to limit the spread of measles.

Autism

Because signs of autism may appear around the same time children receive the MMR vaccine, some parents may worry that the vaccine causes autism. Vaccine safety experts, including experts at CDC and the American Academy of Pediatrics (AAP), agree that MMR vaccine is not responsible for recent increases in the number of children with autism. In 2004, a report by the Institute of Medicine (IOM) concluded that there is no link between autism and MMR vaccine, and that there is no link between autism and vaccines that contain thimerosal as a preservative.

Fact‎

Many carefully performed scientific studies have found no link between MMR vaccine and autism.3456
Keep Reading: Vaccines and Autism

How CDC monitors vaccine safety

CDC and the Food and Drug Administration (FDA) are committed to ensuring that vaccines provided to the public are safe and effective. Once vaccines are licensed or authorized for emergency use in the United States, CDC and FDA continuously monitor them through several safety systems.

Keep Reading: About CDC's Vaccine Safety Monitoring Program

Resources

Organizations

Other resources

Measles, Mumps, and Rubella (MMR) Vaccination: What Everyone Should Know
What Everyone should know about the MMR vaccine. What is the MMRV vaccines? Who should and should no...
MMR & Varicella Vaccines or MMRV Vaccine: Discussing Options with Parents
Discussing MMR and MMRV vaccine options to Parents. Risks and Benefits of each vaccine. Preventing M...
Q&As About Vaccination Options for Preventing Measles, Mumps, Rubella, and Varicella
Questions and Answers About Vaccination Options for Preventing Measles, Mumps, Rubella, and Varicella.
Contraindications and Precautions
Contraindications and Precautions: General Best Practice Guidelines for Immunization. Advisory Commi...
Immunization Schedules
Stay up-to-date on getting recommended vaccines. Here are immunization schedules for people of all a...
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Content Source:
National Center for Emerging and Zoonotic Infectious Diseases (NCEZID)
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