What should you know about black solid stool?

Look at more than colour. Stool that is jet black, sticky or tar-like, unusually foul-smelling, or mixed with weakness and light-headedness is more concerning than stool simply darkened by a meal. Iron tablets, bismuth-containing stomach remedies, and deeply coloured foods can darken bowel movements without bleeding. Conditions such as gastritis, Helicobacter pylori infection, or a peptic ulcer can irritate or damage the upper digestive lining and cause bleeding.

Note when the change began, how often it has happened, and whether the stool is sticky or tarry. Keep a list of medicines and supplements, including iron, aspirin, ibuprofen, and stomach products. Do not stop a prescribed medicine without advice, but contact a clinician promptly if the stool remains black or you cannot explain the change. A clinician may ask about pain, vomiting, dizziness, diet, and medicines before deciding whether examination or testing is needed.

Seek emergency help for black tarry stool with fainting, severe weakness, confusion, breathlessness, rapid heartbeat, vomiting blood, or severe abdominal pain. Even without these symptoms, arrange prompt medical review for a new unexplained black stool, repeated episodes, or black stool while taking medicines that can irritate the stomach or affect bleeding. Do not drive yourself if you feel faint.

Ask whether the appearance could be caused by a food, iron, or bismuth product; whether your medicines raise the chance of digestive bleeding; and whether you need tests for gastritis, Helicobacter pylori infection, or a peptic ulcer.