Causes of bloody stools include disease factors, poor lifestyle and so on. 1. Disease factors: (1) Ulcerative colitis: the main symptoms include abdominal pain, diarrhea, mucus, pus and blood in the stool, and a sense of urgency (discomfort in the lower abdomen, wanting to relieve stool, and a sense of incomplete defecation after defecation). (2) Tumor of digestive tract: including colorectal cancer, etc. The main symptoms include abdominal pain, change in the stool, blood in stool and weight loss. (3) Hemorrhoids: Bleeding from hemorrhoids is usually painless and the amount of bleeding varies. (4) Anal fissure: there is usually severe localized pain when the stool is dry, accompanied by bleeding on the surface of the stool. (5) Polyps: the bleeding is usually small and the blood is attached to the surface of the stool. Inflammatory diseases have blood-voiding stools related to the severity of thinning stools, and even present pus and blood stools. 2. Bad lifestyle: (1) Heavy drinking: it may lead to acute gastric mucosal injury, which may result in upper gastrointestinal bleeding. (2) Dry stools and poor defecation: unreasonable dietary habits may cause dry stools and poor defecation, which may easily cause anal fissure leading to blood in stool when defecating. (3) Sedentary, low-fiber diet, long defecation time, easy to trigger hemorrhoids, resulting in blood in stool. Blood in the stool needs to be taken seriously, and it is recommended to seek timely medical treatment and systematic treatment under the guidance of a doctor.