The duration of MMR vaccine diarrhea varies according to individual constitution, usually 1~2 days, symptomatic treatment can be given. MMR vaccine is a live attenuated vaccine for measles, mumps and rubella. After vaccination, it can stimulate the body to produce anti-measles virus, mumps virus and rubella virus immunity, and can be used to prevent measles, mumps and rubella. It is suitable for measles, mumps and rubella susceptible individuals over eight months of age. Common adverse reactions are fever, pain at the vaccination site, rash, mild parotid gland enlargement and salivary gland enlargement; rare adverse reactions are severe febrile reactions; very rare adverse reactions include allergic rash, anaphylaxis, anaphylactic purpura, thrombocytopenic purpura, arthritis, joint enlargement and pain. Most people will not have diarrhea after MMR vaccination, but a small portion of people will have diarrhea, usually in 1~2 days, can be symptomatic treatment, general supplementation of appropriate fluids, vitamins, etc., can prevent hydroelectrolyte disorders, the patient should pay attention to rest, if diarrhea is very serious, it is recommended to immediately under the guidance of a doctor for targeted treatment, do not take medication without authorization.