The main precaution for taking magnesium sulfate for colonoscopy is to take it as prescribed by the doctor. Before doing colonoscopy to follow the doctor’s instructions for intestinal preparation, that is, taking laxatives (magnesium sulfate), usually in the night before the colonoscopy, the patient needs to take a laxative, and to drink 1000 ~ 2000 ml of water, in order to discharge the feces in the intestines, and fasting on the same night. On the morning of the colonoscopy, the patient is usually required to take another dose of magnesium sulfate and drink water until the feces are completely expelled, until the expulsion is clear water, which allows the colonoscope to get a clearer view of the intestinal tract. If the laxative is not taken in time, the amount of magnesium sulfate is not enough, or the amount of water is not enough, it may result in unclean defecation, leading to fecal matter accumulation in the intestines, which will affect the observation of the intestines by the colonoscopy, so the patient should take the laxative and drink water on time and in accordance with the doctor’s instructions.