Black and red stool: what the colours can mean

Black stool can follow iron, bismuth, or dark foods, but a tarry black appearance may occur when blood has been digested higher in the digestive tract. Bright red blood may come from the lower bowel or the anal area, including irritation from hard stool, although other causes are possible. Seeing both colours can reflect more than one source or a change as blood moves through the digestive system. Gastritis, Helicobacter Pylori Infection, and Peptic Ulcer are upper digestive conditions that may be relevant when black stool is present.

Colour is not enough to diagnose the cause. Note whether blood is mixed into the stool or on its surface, and whether you have pain, diarrhoea, constipation, weakness, or dizziness.

Contact a healthcare professional promptly for unexplained black stool, visible red blood, or a new change that repeats. Keep a list of medicines and supplements, including pain medicines and iron. Do not stop prescribed treatment without advice. Avoid straining and drink fluids if appropriate for you, but do not use constipation or diarrhoea medicines to mask bleeding. If possible, describe the colour, texture, amount, and timing clearly.

Seek emergency care for heavy or repeated bleeding, black tarry stool with red blood, fainting, severe weakness, confusion, breathlessness, a racing heartbeat, severe abdominal pain, or vomiting blood or coffee-ground-like material. Prompt assessment is also needed if you feel increasingly unwell or cannot keep fluids down. These symptoms can accompany significant digestive bleeding.

Ask where the bleeding might be coming from, whether your medicines could contribute, and what examination or tests are appropriate. Share any history of stomach pain, ulcers, digestive illness, constipation, or recent food and supplement changes. Ask whether Gastritis, Helicobacter Pylori Infection, or Peptic Ulcer could explain the black component.