Some people will experience blood in the stool after drinking colonoscopy laxatives. This may be caused by drinking too much laxative, hemorrhoids or anal fissure. 1. Drinking too much laxative: If you drink a lot of laxative at one time, it may cause irritation and damage to the mucous membrane of the gastrointestinal tract, and blood will appear in the stool. If you drink a normal amount of laxatives, blood in the stool usually does not occur. 2. hemorrhoids: if the patient himself suffers from hemorrhoids, drink laxatives when defecating too hard, resulting in venous rupture bleeding, there will be bleeding during defecation. 3. Anal fissure: If the patient has anal fissure, after drinking laxatives, there may also be blood in the stool. In addition to blood in the stool, there will be severe pain in the anal area. If the symptoms of blood in the stool continue to be unrelieved, it is recommended to consult a doctor in a timely manner, under the guidance of the doctor to clarify the cause and targeted treatment, do not take medication on their own, so as not to delay the condition.