Black streaks in the stool are due to undigested food, which comes in contact with blood, certain drugs in the gastrointestinal tract, causing it to become black streaks. This condition can be divided into non-pathological factors and pathological, and can be treated symptomatically according to the different triggers. Non-pathological factors: 1. Diet: If the patient eats dark-colored food or certain drugs, such as duck blood, chicken blood, sheep blood, pig blood, animal liver, iron, bismuth and biochar, black streaks may appear in the stool. Once you stop eating food and drugs that cause black stool, the symptoms can gradually return to normal; 2, improper surgical operations: when patients have nosebleeds, tooth extraction, tonsillectomy and other operations in recent days, the blood swallowed can also lead to black streaks in the stool, and after a period of time, the black stool symptoms will gradually ease. Second, pathological: 1, peptic ulcer: patients with more serious ulcers, ulcer surface larger and deeper, coupled with improper diet, alcohol consumption, etc. will induce upper gastrointestinal bleeding, followed by black stool. You can follow medical advice to use drugs that reduce gastric acid, promote gastric power and enhance gastric mucosa protection, such as omeprazole, cimetidine, famotidine, aluminum thioglycollate, etc.; 2, tumor lesions of the digestive tract: when patients have digestive tract tumors or polyps, the rupture of tumors and polyps can lead to gastrointestinal bleeding and black stools. Patients should go to the hospital for e-colonoscopy in time to avoid delaying the disease. Early surgical resection is the main focus, and later chemotherapy and radiotherapy can be combined to obtain a longer survival time.