What should you know about black stool after endoscopy?

A small amount of blood can be swallowed during an upper endoscopy, especially if the throat or gums were irritated. Iron tablets, bismuth-containing medicines, and some dark foods can also change stool colour. True melaena is usually black, sticky or tar-like, and may have a strong unusual smell. It can indicate bleeding from the stomach or first part of the intestine, including from gastritis, a peptic ulcer, or irritation after a procedure. A colour change alone cannot identify the cause.

Check whether the stool is genuinely tarry and note when it began, how often it occurs, and any medicines or supplements taken. Follow the endoscopy team’s discharge instructions and do not stop a prescribed medicine without advice. Contact the endoscopy unit or clinician promptly if black stools recur, even if you feel well. Take your medication list and procedure report if you attend.

Seek emergency care for repeated black tarry stools, vomiting blood or material resembling coffee grounds, faintness, marked weakness, confusion, shortness of breath, severe abdominal pain, or a fast pounding heartbeat. These signs can occur with significant blood loss. Do not drive yourself if you feel faint; ask someone to take you or call emergency services.

Ask whether the procedure showed irritation, an ulcer, or another possible bleeding source; whether your medicines could darken stool; which symptoms require immediate review; and whether blood tests or a repeat assessment are needed.