Hi & Welcome. I can understand your concern for the black bowel movement. Incomplete data like age, gender, any associated medical illness, medication intake, smoking or alcohol consumption?? Black bowel movement could be due to bleeding or other injuries that take place in the esophagus, stomach, or small intestine most often causes the stool to appear black. The most common condition causing black stools is a bleeding ulcer. Other causes include oesophageal varices (widened and overgrown veins), gastritis, esophagitis, Mallory–Weiss tears, and malignancy. Bleeding can also be due to certain medications such as blood thinners including Aspirin, Warfarin, or some pain killers. You may also have dark, discolored bowel movements after eating dark-colored foods such as black licorice, blueberries, dark chocolate cookies, red-colored gelatin, and beets. Certain medications can also lead to black-colored stools like iron supplements and bismuth-based medications. You are advised to consult a doctor (gastroenterologist) for proper clinical examination and relevant lab tests such as stool tests, CBC, ESR, clotting studies, endoscopy, and angiography to rule out the common causes of bleeding. Hope the advice given above would be useful. Best regards.