After the MMR vaccination, babies can have asymptomatic, localized redness, swelling and hot pain, fever, diarrhea, rash and other manifestations due to different physique, if the symptoms are more serious, it is necessary to consult a doctor in time for treatment. MMR vaccine is a combined vaccine to prevent measles, mumps and rubella, and most babies have no abnormal symptoms after vaccination. A small number of injection site redness, swelling and hard nodules, fever, nausea and diarrhea, skin rash and other adverse reactions are common adverse reactions to vaccination as a normal phenomenon, most of which can subside on their own, without special treatment. If the vaccination adverse reaction is more serious (such as large red rash, chest tightness, dyspnea, persistent high fever, etc.) consider that due to severe allergic reactions, we need to consult a doctor in time for symptomatic and anti-allergic treatment.