Bleeding duodenal ulcer usually takes 3~7 days before black stool, the exact time is related to body condition, severity of bleeding and location of ulcer. 1. Physical condition: If you have coagulation problems or low platelet value, the bleeding will be more than normal, and the duration of black stool will be prolonged, possibly to more than 7 days, it is recommended to combine with their own situation, go to the hospital and take medication under the guidance of the doctor such as lansoprazole enteric capsule. 2. The severity of bleeding: the duration of black stool after bleeding duodenal ulcer is closely related to the degree of bleeding. If the bleeding is more serious and the amount of bleeding is large, the duration of black stool will be prolonged; on the contrary, the duration of black stool is shorter. 3. The location of the ulcer: if the duodenal ulcer occurs in the anterior wall, the amount of bleeding is generally less, so the duration of black stool is shorter; if the ulcer occurs in the posterior wall of the duodenal bulb, the amount of bleeding is generally more, and the duration of black stool may be more than a week, which may be accompanied by abdominal pain, and it is recommended that you go to the hospital in a timely manner in order to avoid the serious consequences of gastrointestinal perforation and other serious consequences. Therefore, the duration of black stool after bleeding duodenal ulcer is closely related to one’s physique, the site of the ulcer and the amount of bleeding, and usually lasts for 3~7 days. If the black stool lasts for a long time and is accompanied by abdominal pain and bloating, it is recommended to go to the hospital in time for examination to clarify the severity of the condition and then formulate a comprehensive treatment plan.