Alternating constipation and diarrhea can be caused by the following: 1. Functional, functional most common irritable bowel syndrome. The cause of irritable bowel syndrome is related to psycho-spiritual factors, for example, some children have to take exams soon and show diarrhea, while others show constipation; some people show alternating diarrhea and constipation, which are related to neurological and psychiatric factors; 2. Pleurisy. The next most common cause is inflammatory bowel disease, which includes Crohn’s disease and ulcerative colitis, and may also be tumors. Therefore, once a patient has alternating diarrhea and constipation, it is recommended that the patient go to a regular hospital and register with the gastroenterology department, and then the doctor will distinguish whether the constipation is functional or organic, or whether relevant tests are needed.