What is the reason for black-coloured stool?

When blood is exposed to digestive juices, it can turn stool black and tarry. Possible sources include a peptic ulcer, gastritis, or irritation associated with Helicobacter pylori infection. A person can have digestive bleeding without pain, so the absence of discomfort does not settle the question.

Iron supplements and bismuth-containing medicines can also darken stool. A food-related change is more plausible when the colour follows a strongly pigmented meal and the stool remains otherwise typical. A clinician may need to examine you to separate these possibilities.

Check whether you recently started iron, bismuth, or a dark food, but do not assume that is the explanation if the stool is sticky, tarry, repeated, or foul-smelling. Contact a clinician promptly and describe the change accurately. Keep the medicine packaging or a written list available, including non-prescription pain medicines.

Get emergency help for black stool with faintness, weakness, confusion, breathlessness, vomiting blood, severe abdominal pain, or a rapid heartbeat. These signs can accompany substantial bleeding. Seek same-day assessment for repeated tarry stools even if you otherwise feel steady.

Ask which causes fit the stool's texture and timing, whether your medicines may irritate the stomach, and whether testing for gastritis, Helicobacter pylori infection, or peptic ulcer disease is needed.