Generally, you do not need to start drinking laxatives the day before for a morning colonoscopy, usually 4 to 6 hours before the morning colonoscopy. Enteroscopy is a kind of endoscopic examination used to detect the intestines, which can directly observe the color of the patient’s intestinal mucosa, the texture of blood vessels, the presence of mucosal pallor, congestion, swelling, as well as erosion, ulceration, proliferative changes and cumbersome organisms, etc. Enteroscopy can be divided into ordinary enteroscopy and painless enteroscopy, which can be used to diagnose intestinal diseases and carry out treatments such as haemostasis, polypectomy and other treatments. During colonoscopy, the doctor slowly puts the colonoscope through the anus, injects a small amount of gas and then adjusts the angle accordingly to observe the intestinal lesions and carry out the corresponding treatment. Therefore, it is necessary to ensure a clear field of vision to avoid blocking the field of vision of intestinal contents and feces, resulting in missed diagnosis, etc. Therefore, it is necessary to take a laxative to clean the intestinal tract before doing colonoscopy.