What causes black stool?

Iron supplements, bismuth products, and strongly coloured foods can make stool look dark. Bleeding higher in the digestive system can produce melaena: stool that is black, sticky, tar-like, and often unusually odorous. Gastritis may inflame the stomach lining; Helicobacter pylori infection can contribute to stomach irritation and ulcer formation; a peptic ulcer can bleed. The presence of black stool does not by itself show which explanation applies.

Record what you have taken and eaten, and note whether the stool is formed, sticky, or tarry. Keep track of stomach pain, nausea, vomiting, light-headedness, or unusual tiredness. Get medical advice if the change persists, returns, or cannot be explained by a recent food or medicine. Never change prescribed treatment on your own.

Go to urgent care if black stool occurs with fainting, severe weakness, rapid breathing, confusion, severe abdominal pain, blood in vomit, or coffee-ground vomit. These combinations may signal active digestive bleeding. A new unexplained tarry stool deserves prompt review even when other symptoms are absent.

Ask which cause fits the stool’s appearance and your medicine list, whether testing for Helicobacter pylori is appropriate, and how quickly you should be reviewed. Share a timeline and any photographs only through a secure clinical service.