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Measles, Mumps, and Rubella (MMR) Vaccine

The measles, mumps, and rubella (MMR) vaccine is one of the recommended childhood vaccinations. The three-in-one vaccine protects against three potentially serious illnesses. In most states, proof of the MMR vaccine is required for children to enter school. But if you are an adult who has not had the vaccination or the diseases, it may be important for you to receive the MMR shot, too.

What Are Measles, Mumps, and Rubella?

Measles, mumps, and rubella are viral diseases. All have the potential to be very serious.

Measles is characterized by fever, cough, runny nose, conjunctivitis (pinkeye), and a red, pinpoint rash that starts on the face and spreads to the rest of the body. If the measles virus infects the lungs, it can cause pneumonia. Some older children infected with the virus suffer from encephalitis (inflammation of the brain), which can cause seizures and permanent brain damage.

The mumps virus usually causes swelling in the salivary or parotid glands, just below the ears, giving the appearance of chipmunk cheeks. Before the development of the mumps vaccine, mumps was the most common cause of meningitis (inflammation of the lining of the brain and spinal cord) and acquired deafness in the U.S. In men, mumps can infect the testicles, which can lead to infertility.

Rubella is also known as German measles. In children, rubella infection causes a mild rash on the face, swelling of glands behind the ears, and in some cases swelling of the small joints and a low-grade fever. Most children recover quickly from rubella with no lasting effects. If a pregnant woman gets rubella, however, the results can be devastating. If she is infected during the first trimester of pregnancy, there is a great chance her child will have a birth defect such as blindness, deafness, a heart defect, or mental retardation.

Who Should and Shouldn't Get the MMR Vaccine

MMR is given in two shots, typically during childhood. Children should receive the first shot between 12-15 months and the second between 4-6 years of age.

If you're not sure if you have had the diseases or the vaccines (prior to 1971 it was given in three separate shots), you can get the MMR vaccine as an adult. You should speak to your doctor about the vaccine if:

  • You were born after 1956 (if you were born during or before 1956, you are presumed to be immune, because many children had the diseases then).
  • You work in a medical facility.
  • You are planning to or may become pregnant.

You should not receive the shot if:

  • You experienced a severe allergic reaction following the first MMR shot.
  • You are allergic to gelatin or neomycin.
  • You may be pregnant or are planning to become pregnant in the next four weeks. (The vaccine is safe if you are breastfeeding.)
  • Your immune system is suppressed because of cancer drugs, corticosteroids, or AIDS.

MMR Risks and Side Effects

Most people who receive the MMR vaccine have no problems from it. Some experience minor soreness and redness at the injection site or fever.

Other possible side effects are less common. They include:

  • Fever (1 in 5 children)
  • Rash (1 in 20)
  • Swollen glands (1 in 7)
  • Seizure (1 in 3,000)
  • Joint pain/stiffness (1 in 100 children; more common in adults, particularly women)
  • Low platelet count/bleeding (1 in 30,000)
  • Encephalitis (1 in 1 million)

Despite speculation and considerable publicity, there is no evidence that MMR vaccine causes autism. The potential benefits of the vaccine far outweigh its potential risks.

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WebMD Medical Reference

Reviewed by Renee A. Alli, MD on May 26, 2014

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