Fever from MMR vaccination usually goes down in about 3 days. MMR vaccine is a combined measles, mumps and rubella vaccine, which can make the body produce antibodies to measles virus, mumps virus and rubella virus after injection. However, some patients may have the adverse reaction of fever after vaccination. This is mainly due to the immune response of the body during the process of antibody production. The fever usually subsides within three days after the injection. Fever from the MMR vaccine can be relieved by applying a cold towel or taking a warm bath, or, if necessary, taking oral medications such as acetaminophen and ibuprofen under the guidance of a doctor to reduce the fever. To summarize, fever is relatively common after MMR vaccination. When fever persists without relief, you should seek medical advice as soon as possible to clarify the cause of the disease and treat it according to the advice of healthcare professionals.