A drop of dark red blood on the surface of the stool even if the blood, may be hemorrhoids, anal fissure, colon cancer and other diseases caused by, you should seek medical attention in a timely manner, to clarify the cause of the disease after treatment. 1. Hemorrhoids: the disease caused by venous congestion and expansion of the anal canal or the lower end of the rectum, there will be blood in the stool, pain, anal itching and other symptoms, such people should pay attention to maintain a regular routine, less spicy and stimulating food, can be used locally, lidocaine, hydrocortisone and other drugs for treatment. 2. Anal fissure: anal fissure can also cause blood in stool, which is caused by splitting of the skin of anal canal, and there will be anal pain, constipation and other symptoms, which can be treated with sitz bath. 3. Colon cancer: malignant tumors of the colon and rectum can also cause blood in stool, with symptoms such as fatigue, abdominal pain, weight loss, etc. They should be actively prepared for surgery and cooperate with postoperative radiotherapy. All the above medicines and treatments should be carried out under doctor’s guidance.