Blood in the stool with white mucus may be caused by food allergy, chronic colitis, rectal cancer and other diseases. 1. Food allergy: This disease is caused by an allergic reaction after ingesting certain food proteins through the mouth, common allergens include milk, fish, peanuts, eggs, etc. It is related to heredity, too much vitamin intake, etc. Patients may have nausea, vomiting, diarrhea, bloody stools and mucus. Patients will have nausea, vomiting, diarrhea blood and mucus stools and other symptoms, so there is blood in the stool with white mucus. 2. Chronic colitis: the direct cause of the disease is not yet clear, may be related to heredity, long-term mental stress, intestinal immune dysfunction, infection and other reasons. Common symptoms include abdominal pain, diarrhea, mucous blood stools, etc. Therefore, patients will have the performance of having white mucous substance with blood in stools. 3. Rectal cancer: common risk factors include improper diet, heredity, age over 50, chemical carcinogens, schistosomiasis and so on. Patients may have symptoms such as blood and mucus on the surface of stools, anal dropping sensation, urgency and heaviness (discomfort in the lower abdomen, wanting to defecate very much, feeling of incomplete defecation after defecation) and so on. It is recommended that patients with blood in the stool and white mucus should go to the hospital in time to improve the examination and clarify the specific cause of the disease.