What does dark-coloured diarrhoea mean?

Dark brown loose stool can result from foods, supplements or faster bowel movement during an illness. Black, sticky, tar-like stool with a strong smell may indicate bleeding higher in the digestive tract and should not be dismissed. Infection can cause diarrhoea with cramps, fever, nausea or vomiting; travel or untreated water can be relevant. Ongoing loose stools may also occur with [Food Intolerance](/conditions/food-intolerance/), [Coeliac Disease](/conditions/coeliac-disease/) or inflammatory bowel conditions. Colour alone cannot show which cause is present.

Keep drinking small, frequent amounts of water or an oral rehydration drink, especially after each loose stool. Eat simple foods if hungry and avoid alcohol. Note recent foods, medicines, travel, sick contacts and whether the stool is dark brown or black and tarry. Do not take anti-diarrhoeal medicine if you have blood, fever or severe pain without medical advice. [Food Poisoning](/conditions/food-poisoning/) and [Gastroenteritis](/conditions/gastroenteritis/) are possible explanations, but examination may be needed.

Get urgent medical help for black tarry stool, visible blood, fainting, confusion, severe weakness, severe abdominal pain, repeated vomiting or signs of dehydration such as very little urine and a dry mouth. Seek prompt advice if diarrhoea persists, follows recent antibiotics or travel, or is accompanied by fever. Children, older adults and people with ongoing medical conditions can become dehydrated quickly.

Ask: Is the stool dark brown or tar-like? Could a medicine or food explain it? Do I need stool tests, blood tests or assessment for bleeding? How should I replace lost fluids?