The MMR rash will subside in about 2 to 3 days. MMR refers to the MMR vaccine, which can prevent three diseases, mainly measles, mumps and rubella, and is suitable for children over 8 months old. There may be adverse reactions after this vaccination, mainly 7~12 days after the vaccination, there may be swollen lymph nodes in the cheeks or neck, and there may also be a slight fever or rash, but this rash is not contagious, and it can usually subside after 2~3 days, so you don’t need to worry too much. If you have a rash after receiving MMR vaccination, you should keep your skin clean and hygienic, and do not scratch your skin. If the rash does not subside after MMR vaccination, you should consult a doctor for treatment.