Pentavalent rotavirus vaccine after 4 days of diarrhea, consider may be the vaccination normal reaction, may also be due to improper diet, gastroenteritis and other factors, can be under the guidance of the doctor to improve the living habits, medication and other ways to treat. 1. Vaccination reaction: generally due to the body after vaccination, the vaccine in the body to produce antibodies in the process, causing the body’s immune response, and then the phenomenon of diarrhea, you can go to the hospital in time for consultation. 2. Improper diet: It is usually due to excessive consumption of too cold food or spicy food after vaccination, which will stimulate the gastrointestinal tract, and then the phenomenon of diarrhea can be relieved by improving the diet, nutritional balance and other ways to alleviate the symptoms. 3. Gastroenteritis: It may be due to the fact that one already suffers from gastroenteritis, which stimulates the human body after vaccination, and then the phenomenon of diarrhea occurs, which can be treated by using drugs such as cotrimoxazole enteric capsule and rabeprazole sodium enteric capsule according to the doctor’s instructions. If you have diarrhea 4 days after the pentavalent rotavirus vaccine injection, you should go to the hospital in time to avoid delaying your condition.