What should you know about black soft stool?

Stool that is truly black, sticky or tar-like, and has an unusually strong smell is called melaena. It can form when blood is digested as it passes through the stomach or small intestine. Possible sources include irritation of the stomach lining, a peptic ulcer, or infection with Helicobacter pylori. These conditions can sometimes cause upper digestive tract bleeding even when stomach discomfort is mild or absent.

Dark stool is not always blood. Iron supplements, bismuth-containing medicines, and foods with very dark colouring can change stool colour. The appearance, texture, smell, and timing of the change all matter. A clinician may need to review your medicines, examine you, and arrange tests to identify the cause.

If the colour is new and you cannot clearly explain it by a recent food or medicine change, contact a healthcare professional promptly. Note when it began, how many bowel movements have looked this way, and whether the stool is sticky or tarry. Bring a list of prescribed medicines, over-the-counter products, and supplements. Do not stop a prescribed medicine without medical advice, but mention aspirin, anti-inflammatory painkillers, blood thinners, iron, and bismuth products because they can affect bleeding risk or stool colour.

Seek emergency care for black tarry stool with vomiting blood or material that looks like coffee grounds, fainting, severe weakness, confusion, breathlessness, rapid heartbeat, or significant abdominal pain. Urgent assessment is also needed if black stools keep occurring, become more frequent, or appear while you take a blood thinner. These features can accompany meaningful blood loss and should not be judged by stool colour alone.

Ask: Could my medicines or supplements explain the colour? Does the texture suggest digested blood? Do I need blood tests or an examination of the upper digestive tract? Should I be assessed for gastritis, a peptic ulcer, or Helicobacter pylori infection? What warning signs should prompt emergency care?