My stool is dark brown, almost black: what should I know?

Brown stool can become darker with changes in food, hydration, or transit through the bowel. Very dark stool may also follow iron or bismuth medicines. Black stool is more concerning when it is shiny, sticky, tar-like, or has a strong unusual smell, because digested blood can create that appearance. Gastritis, a peptic ulcer, and Helicobacter pylori infection are possible causes, though appearance alone cannot diagnose any of them.

Look at the next bowel movement in good light and record what you see. Review recent meals, iron, bismuth, and other medicines, then contact a clinician if the colour is truly black, keeps recurring, or you are unsure. Keep drinking normally unless a clinician has told you otherwise. Do not use extra anti-inflammatory painkillers to manage stomach discomfort before getting advice.

Seek emergency help if dark stool occurs with dizziness, fainting, unusual weakness, pale or clammy skin, vomiting blood, confusion, or severe abdominal pain. Prompt assessment is needed for repeated black or tarry stools, especially when taking medicines that affect bleeding. Do not wait for pain to develop before seeking advice.

Ask whether the colour fits a food or medicine effect, whether a stool or blood test is needed, and which changes should send you straight to emergency care.