What should you know about black stool look like?

Stool caused by digested blood is often called melaena. It may look deep black rather than merely dark brown, with a sticky or tar-like texture and a stronger, unpleasant smell. Bleeding can arise in the oesophagus, stomach, or the first part of the small intestine. Gastritis, Helicobacter pylori infection, and peptic ulcers are among the conditions that can irritate or damage this area.

Iron supplements, bismuth-containing medicines, and some very dark foods can also turn stool black without bleeding. Colour alone cannot reliably distinguish these causes. The timing of the change, its texture, associated symptoms, and any medicines you take all help a clinician judge what is happening.

If the stool is newly black, contact a healthcare professional promptly, especially when you have not recently started iron or a bismuth medicine. Make a note of when it began, whether it was sticky or tarry, and any recent vomiting, abdominal discomfort, or medicine changes. Do not stop a prescribed medicine without medical advice, but bring its name or packaging to the assessment.

Seek emergency care for black tarry stool with dizziness, fainting, marked weakness, confusion, breathlessness, a fast heartbeat, pale or clammy skin, severe abdominal pain, or vomiting blood or material that resembles coffee grounds. These can accompany significant blood loss. Urgent assessment is also appropriate if black stools keep occurring, become more frequent, or appear after taking medicines that can increase bleeding risk.

Ask whether the appearance could be related to a medicine or food, whether you need testing for bleeding or anaemia, and which warning symptoms should bring you back urgently. You can also ask whether evaluation for gastritis, Helicobacter pylori infection, or a peptic ulcer is appropriate based on your symptoms and medical history.