There are many causes of mucus stool and redness, the common ones are ulcerative colitis, intestinal polyps and rectal cancer. 1. Ulcerative colitis: it mainly involves the colon and rectum, and is a chronic non-specific intestinal inflammatory disease caused by many reasons. The main manifestations are intermittent diarrhea, red mucus stool, and acute and severe pain. 2. Intestinal polyp: the surface of intestinal mucosa protrudes into the intestinal lumen of the bulging lesion, if the volume of larger villous polyps can appear a lot of mucus stool, bleeding occurs, that is, mucus stool red. 3. Rectal cancer: there is no obvious symptom in the early stage, with the progress of the disease, the tumor lesion breaks down and bleeds and necrotic, and the phenomenon of red mucus stool can appear. There may be other reasons for red mucus stool, such as intestinal tuberculosis, etc. It is recommended to go to the hospital as soon as possible to find out the reasons and standardize the treatment under the guidance of professional doctors.