Diarrhea after MMR vaccination may be related to the adverse reaction to the vaccine, or may be related to intestinal flora imbalance, bacterial enteritis, etc., which can be treated symptomatically and causally to improve. 1. Diarrhea caused by adverse reactions to vaccines: generally diarrhea symptoms are mild, drink plenty of water, the symptoms can be relieved in about three days, you can also take montelukast for symptomatic treatment of diarrhea symptoms. 2. Diarrhea caused by intestinal flora imbalance: if the diarrhea appeared before taking antibiotics for a period of time can be considered flora imbalance, you can take probiotic drugs to regulate, such as bifidobacteria triple bacterium, bacillus subtilis bifidus and so on. 3. Bacterial enteritis caused by diarrhea: if diarrhea before the emergence of a history of unclean diet or collective diarrhea, it is considered to be bacterial enteritis, you can take antibacterial drugs for the cause of treatment, such as cephalosporin, cefaclor and so on. These drugs can have side effects such as nausea, vomiting, allergy, dizziness, etc. When using them, they need to be taken under the guidance of a doctor. Diarrhea after vaccination is recommended to consult a doctor in a timely manner, under the guidance of the physician symptomatic treatment and causative treatment, do not self-medication, so as not to delay the condition.