My stool is black in colour: what should I know?

Stool may look dark after iron tablets, bismuth-containing medicines, or strongly coloured foods. Bleeding can make stool black, shiny, sticky, and unusually foul-smelling. Possible sources include gastritis, a peptic ulcer, or Helicobacter pylori infection. Colour is not enough to identify the cause, and a person can have significant bleeding without strong stomach pain.

Contact a medical service promptly and describe the colour, texture, smell, and when it began. List every medicine and supplement, including pain relievers and iron. Do not stop a prescribed medicine without advice, and avoid taking additional anti-inflammatory painkillers until a clinician has guided you. If possible, note whether the stool repeats and whether you have dizziness, weakness, or vomiting.

Call emergency services for black stool with faintness, confusion, marked weakness, pale or clammy skin, rapid breathing, vomiting blood, or severe abdominal pain. Urgent assessment is also needed if black stools continue or you take medicines that increase bleeding risk. Bring your medication list and do not drive yourself if you feel faint.

Ask whether the appearance could be from a medicine or food, whether bleeding needs testing, and whether gastritis, ulcer disease, or Helicobacter pylori should be investigated.