The danger of not drinking 2000 ml of colonoscopy is that it will make the intestinal cleanliness low, reduce the lesion detection rate, and even cause the colonoscopy to be unable to be carried out properly. Patients before the colonoscopy is required to make adequate intestinal preparation, that is, to discharge the intestinal debris, so as to ensure that the colonoscopy can be clearly observed in the intestines. Therefore, when drinking laxatives for intestinal preparation, the harm caused by not drinking is that there is more feces in the intestines, so it is impossible to clearly observe and cover up some diseases, and even make the colonoscopy impossible to be carried out. Laxatives to drink before the colonoscopy are electrolyte bulk, magnesium sulfate, sodium pico-sulfate, senna, etc., brewed into a solution of 2000 ml to drink. The solution of electrolyte dispersions is the most widely used and has a poor taste, however, it has no significant side effects on the body, so try to drink it all and prepare your intestines so that you can start the colonoscopy without any problems. If you can’t drink it all you must ask your doctor’s advice and not blindly do the colonoscopy.