You can have a colonoscopy after drinking laxatives for about 6 hours, depending on how well you prepare your intestines, i.e. you can have an e-colonoscopy only after drinking laxatives to clean out all the stool in your intestines. In general, there is a picture of bowel preparation in the bathroom of the hospital, so you can refer to the picture for bowel preparation. The best bowel preparation standard is to have clear, yellowish liquid stool without any fecal residue, similar to urine. The above-mentioned good bowel preparation is mainly related to drinking a lot of water. After drinking laxatives, you must drink a lot of boiled water to facilitate the bowel movement, and you need to consult the medical staff of the endoscopy center for details.