Vaccine is a foreign stimulus to human body, and after vaccination, it may cause local or systemic reactions of different degrees while generating immunity, and systemic reactions may be manifested as diarrhea; at the same time, it may also be a gastrointestinal stress reaction or intestinal flora disorder after vaccination, and most patients can get better on their own within 1-3 days. If the symptoms are severe, you can take drugs such as montelukast to stop diarrhea under the guidance of the doctor to avoid electrolyte disorders caused by diarrhea. If necessary, a relevant examination should be conducted to determine whether there is a gastrointestinal bacterial or viral infection, and medications such as levofloxacin or metronidazole can be taken under the guidance of a doctor. Local redness, swelling, pain and itching at the injection site may occur after vaccination; systemic adverse reactions such as weakness, dizziness, abdominal pain, etc., and diarrhea may occur, which are usually common adverse reactions and may disappear within a few days, and can be observed. In serious cases, seek medical attention and report to the vaccination unit. Patients are advised to ensure a light diet, and may consume light and easily digestible foods such as congee and noodle soup to avoid re-irritating the gastrointestinal mucosa. Drinking more water to accelerate the metabolism of the body can promote the improvement of the discomfort symptoms.