Simethicone oil belongs to surfactant, before doing colonoscopy simethicone oil should be a bottle to drink. Patients to do colonoscopy before to empty the intestine, in order to clearly see the intestinal wall mucosa situation, when the application of laxatives defecation, patients with a large amount of gas residue in the intestinal tract, at this time the patient through the taking of ximethicone oil, to change the intestinal bubble and intestinal wall, the bubble and the tension between food, promote gastrointestinal peristalsis, accelerated gas discharge, in order to clear the display of intestinal wall, at this time need to be a bottle of drink, only a small amount of gas can not make all the Discharge. In addition, generally simethicone oil after oral intake, through the intestinal tract is all excreted, rarely absorbed, therefore, drink a bottle will not produce a lot of adverse reactions. All of the above medications should be used under the guidance of a doctor, avoid self-medication.