The most common mumps vaccine side effects are fever, mild rash, and gland swelling in the cheeks. There are also rare reports of seizures, bleeding disorders, and allergic reactions.
The only mumps vaccine on the market in the United States is M-M-R II® Vaccine manufactured by Merck & Co. It is a combination vaccine against measles, mumps, and rubella, also known as the MMR vaccine.
The mumps vaccine is usually given to children in a series of two separate 0.5-mL injections (shots) in the upper arm or thigh. The first shot is recommended at 12-15 months of age. The second shot is given at 4-6 years of age, or before starting school.
The mumps vaccine is a live attenuated vaccine, meaning it contains a live mumps virus that has been significantly weakened. It commonly causes a mild illness similar to mumps with symptoms like gland swelling, fever, and feeling sick for 2-3 days.
- Mild rash
- Swelling of the glands in the cheeks
- Temporary pain and stiffness in joints (mostly teenagers and adults)
About 1 in 3,000 children who get a mumps vaccine develop a high fever that causes a seizure (febrile seizure).
About 1 in 30,000 children who get a mumps vaccine develop thrombocytopenia, a temporary condition involving low blood platelet counts. Symptoms include bruising or bleeding under the skin.
Less than 1 in 1,000,000 children who get a mumps vaccine develop a serious allergic reaction (anaphylaxis). Symptoms develop within a few minutes or hours of vaccination, and may include throat swelling, breathing problems, skin rash, hives, or wheezing.
Mumps vaccines have been linked to reports of deafness, long-term seizures, coma, decreased level of consciousness, and permanent brain damage. It is unknown if they were caused by the vaccine.
The following side effects have been linked to mumps vaccine:
- Acute disseminated encephalomyelitis (ADEM)
- Allergic reaction
- Atypical measles
- Bronchial spasm
- Diabetes mellitus
- Ear infection (otitis meida)
- Erythema multiforme
- Facial swelling
- Febrile seizures (high fever causing seizure)
- Guillain-Barré Syndrome (GBS)
- Lymphadenopathy (enlarged lymph nodes)
- Mumps inclusion body encephalitis (MIBE)
- Neurological disorders
- Ocular palsies
- Optic neuritis
- Pneumonia and pneumonitis
- Rash (mumps-like rash)
- Sore throat
- Stevens-Johnson Syndrome (SJS)
- Syncope (fainting)
- Subacute sclerosing panencephalitis (SSPE)
- Transverse myelitis