When your stool is black, it can mean different things depending on the context:

• Upper gastrointestinal bleeding: Black or tarry stools (called melena) often indicate bleeding in the upper digestive tract, such as the esophagus, stomach, or first part of the small intestine. The blood turns black as it is digested while passing through the GI tract, resulting in a sticky, tar-like, foul-smelling stool. This bleeding can be caused by peptic ulcers, gastritis, esophageal tears (Mallory-Weiss syndrome), varices (enlarged veins), abnormal blood vessels, or cancers of the digestive tract

• Medications and supplements: Iron supplements, bismuth-containing medicines (like Pepto-Bismol), and activated charcoal can darken stool to black without indicating bleeding

• Certain foods: Eating black licorice, blueberries, blood sausage, or foods with dark or red coloring can also cause black or dark stools that are harmless

If black stool is accompanied by symptoms such as stomach pain, vomiting blood, weakness, or persists over time, it is important to seek medical evaluation promptly, as it may signal serious internal bleeding or other gastrointestinal conditions

. In summary, black stool can either be due to harmless causes like diet or medications, or it can be a sign of potentially serious bleeding in the upper GI tract requiring medical attention.