Oral administration of mannitol usually results in a significant bowel movement in about 1-2 hours. Mannitol is usually a 20% solution of mannitol, which after oral administration into the digestive tract acts as an osmotic water absorber, increasing the water in the intestine, thus diluting the stool and cleansing the intestine. It is often used clinically for colonoscopy or intestinal preparation for surgery. After the application of mannitol, the effect of defecation is usually achieved within a short time. Fast ones may have diarrhea in about half an hour to an hour, and slower ones may have significant diarrhea with watery stools in about 2 hours. However, it should be noted that mannitol does not contain ions and its application may cause ionic disturbances in patients. In particular, mannitol is not recommended for patients with previous kidney disease, thyroid disease or severe internal environmental disorders. Mannitol must be applied according to medical advice, and different laxatives will be used for different disease conditions, so do not use mannitol blindly.