Black and yellow poop: what to know

Yellow stool can appear when bile moves quickly through the bowel, during diarrhoea, or after changes in diet. A black component may come from iron, bismuth or dark foods. However, black, sticky, tarry stool can be digested blood from the upper digestive tract. Gastritis or a peptic ulcer may cause this pattern, and Helicobacter Pylori Infection can be associated with ulcer disease. A mixed colour may reflect separate changes rather than one diagnosis, so an image or description alone is not enough to identify the cause.

Note the texture, smell, timing and number of bowel movements. List recent foods, supplements and medicines, including iron, bismuth, anti-inflammatory painkillers and blood thinners. Arrange prompt medical advice if black stool continues or appears tar-like. Sip fluids during loose stools. Avoid alcohol, and do not self-treat suspected bleeding with anti-diarrhoeal medicines or by changing prescribed treatment.

Go to emergency care for fainting, severe dizziness, unusual sleepiness, confusion, pale or clammy skin, severe abdominal pain, vomiting blood, coffee-ground vomit, or repeated black stools. Urgent assessment is also sensible when symptoms are worsening or you cannot keep fluids down.

Ask whether the colour suggests digested blood, whether a medicine or supplement could explain it, and whether you need blood tests, stool testing or an examination. Ask which symptoms should trigger immediate return.