Black and smelly stool: causes and when to get help

Stool smell varies with foods, supplements, bowel speed, and gut bacteria. Iron or bismuth can make stool dark, while certain foods can affect both colour and odour. Black, sticky, tar-like stool with a powerful offensive smell is a different pattern: digested blood can produce this appearance when bleeding occurs in the upper digestive tract. Gastritis, Helicobacter Pylori Infection, and Peptic Ulcer may affect that area and can be associated with black stool. The smell itself does not prove bleeding, so the full pattern matters.

Consider accompanying symptoms such as upper-abdominal pain, nausea, vomiting, pallor, light-headedness, or unusual tiredness. A recent medicine or food change is also useful information.

If the change followed a new supplement, stomach medicine, or strongly coloured food, record the timing and monitor the next bowel movements without stopping prescribed medicines. Seek prompt clinical advice if the black colour is unexplained, tar-like, or repeats. Drink normally if you can and avoid self-treating possible bleeding with laxatives or anti-diarrhoeal medicines. Give the clinician a complete list of medicines, supplements, and recent digestive symptoms.

Get urgent help if black smelly stool occurs with fainting, severe weakness, confusion, breathlessness, a fast heartbeat, severe abdominal pain, vomiting blood, or vomit resembling coffee grounds. Repeated tarry bowel movements warrant prompt assessment even without pain. Worsening symptoms can indicate digestive bleeding and require evaluation in person.

Ask whether the smell and colour fit a medicine or food effect, whether bleeding needs to be ruled out, and which symptoms should send you to urgent care. Explain when the change began, whether stool is sticky or tar-like, and any pain, vomiting, dizziness, or weakness. Ask if Gastritis, Helicobacter Pylori Infection, or Peptic Ulcer is relevant.