The causes of diarrhea with mucus include ulcerative colitis, bacillary dysentery, rectal cancer and so on. 1. Ulcerative colitis: due to inflammation in the colon, irritation of the colon mucosa, resulting in ulceration, erosion, edema, etc., triggering diarrhea symptoms in patients. In diarrhea, the ulcerated surface of the colon mucosa, the erosion surface will produce mucus, along with the fecal discharge, thus leading to the patient’s diarrhea with mucus. 2. Bacterial dysentery: due to the presence of bacterial infection in the intestinal tract, it will stimulate the intestinal mucosa, leading to the symptoms of diarrhea. It will cause congestion, edema, necrosis and erosion of intestinal mucosa, which will be discharged with feces and lead to mucus feces in patients. 3. Rectal cancer: due to the tumor occupying position in the intestinal tract, it stimulates the intestinal mucosa, secretes more mucus and increases the frequency of defecation, thus leading to diarrhea with mucus stools. If the patient has diarrhea with mucus, it is recommended that the patient go to the hospital in time. Improve the colonoscopy, color ultrasound, laboratory tests, etc., to clarify the cause of the disease, and follow the doctor’s instructions for treatment, so as not to delay the condition.