Having black stool: what you should know

The appearance matters. Iron supplements, bismuth-containing medicines and strongly coloured foods can darken stool. Black stool that is tar-like, sticky, unusually foul-smelling or accompanied by weakness may contain digested blood from the upper digestive tract. Gastritis can inflame the stomach lining and bleed. A peptic ulcer can also bleed, sometimes with upper abdominal discomfort or no pain. Helicobacter Pylori Infection is one possible contributor to ulcer disease. Black stool alone cannot identify the source.

If the colour change is new, note its texture, timing, medicines, supplements and foods, and contact a clinician promptly for advice. Do not stop a prescribed medicine without guidance. Avoid taking anti-inflammatory painkillers for stomach symptoms unless a clinician has advised you to use them. A clinician may examine you and arrange blood or stool tests, depending on the history.

Go to emergency care for black tarry stool with dizziness, fainting, marked weakness, confusion, rapid heartbeat, vomiting blood or material resembling coffee grounds, severe abdominal pain, or cold clammy skin. Get same-day medical advice for repeated black stools, even if pain is absent. Bleeding can worsen without obvious discomfort, so do not wait for another symptom before seeking help.

Could my medicines or supplements explain the colour? Does the texture suggest digested blood? Do I need testing for an ulcer, gastritis or Helicobacter Pylori Infection? Which pain relievers should I avoid?