What should you know about black stool with no smell?

Iron supplements, bismuth-containing medicines and strongly coloured foods can darken bowel movements. A digestive-tract bleed can also make stool black; it is often sticky, shiny or tar-like and may have a strong odour, but smell is not a reliable way to rule bleeding in or out. Gastritis and a peptic ulcer are possible upper digestive causes, while Helicobacter Pylori Infection can contribute to ulcer disease. A single dark stool cannot establish which explanation applies.

Think back over the last day or two: record the colour, whether the stool was formed or sticky, and any iron, bismuth or anti-inflammatory medicine you used. Do not stop a prescribed medicine without advice. If the colour returns to normal after a clear food or medicine trigger and you feel well, arrange routine advice if it recurs. A clinician may review your medicines, examine you and choose blood or stool tests based on the history.

Seek urgent medical care for repeated black stools, tar-like stool, vomiting blood or material resembling coffee grounds, faintness, unusual weakness, breathlessness, confusion, severe abdominal pain or a fast heartbeat. These signs can occur with significant digestive bleeding. Seek prompt advice even without these symptoms if you take a blood thinner, have a history of ulcers, or the dark stool has no clear explanation.

Could my medicines or supplements explain the colour? Does the texture suggest digested blood? Do I need testing for gastritis, Helicobacter Pylori Infection or a peptic ulcer? What changes should make me seek urgent help?