What should you know about black stool not tarry?

Black stool that is not sticky or tar-like may come from food, iron or medicines, while truly tarry black stool can indicate digestive bleeding and needs prompt medical assessment. Colour alone cannot identify the cause. Consider what you ate or took recently, whether the change continues, and whether you feel unwell.

Dark foods can temporarily change stool colour. Iron tablets and some medicines containing bismuth can also make bowel movements look black or dark green. This colour change is different from melaena, the medical term for stool caused by digested blood. Melaena is often black, shiny, sticky or tar-like and may have a particularly strong smell.

Bleeding in the oesophagus, stomach or the first part of the small intestine can be digested as it passes through the gut. Causes can include inflammation of the stomach lining, infection with Helicobacter pylori, or a peptic ulcer. These conditions may also cause upper-abdominal discomfort, nausea or vomiting, but bleeding can sometimes occur without much pain.

Look at the stool’s texture as well as its colour. Make a note of recent foods, iron or bismuth-containing products, and medicines such as anti-inflammatory pain relievers. Do not stop a prescribed medicine without advice, but tell a clinician exactly what you use.

If the stool is genuinely black and tarry, or if the colour change has no clear explanation, arrange medical advice promptly. A clinician may ask about your symptoms and medicines, examine you, and decide whether blood tests or digestive-tract testing is appropriate. Keep hydrated if you can drink normally, and avoid alcohol until the cause is clearer.

Seek emergency care now for black, tarry stools with dizziness, fainting, unusual weakness, confusion, shortness of breath, a fast heartbeat, severe abdominal pain, or vomiting blood or material that looks like coffee grounds. These symptoms can accompany significant digestive bleeding.

Arrange prompt assessment even without those symptoms if black stools recur, become sticky or tar-like, or appear after starting a medicine that can irritate the stomach. Do not wait for the stool to become painful before seeking help.

You could ask: Could my food, iron or another medicine explain the colour? Does the texture suggest digested blood? Should I be checked for gastritis, Helicobacter pylori infection or a peptic ulcer? Which symptoms mean I should go straight to emergency care?