IBS and black stool: what to know

Melaena is often black, sticky, and unusually strong-smelling because blood has been altered as it passes through the digestive tract. Causes can include a peptic ulcer, gastritis, or Helicobacter pylori infection. Iron medicines, bismuth-containing products, and some dark foods can also change stool colour, but appearance alone cannot safely identify the cause. IBS can involve abdominal discomfort and altered bowel habits, but it does not explain digestive bleeding.

If stool is black or tarry, contact a healthcare service promptly, especially if this is new or repeated. Tell them about iron, bismuth, anti-inflammatory painkillers, blood thinners, alcohol use, abdominal pain, and any vomiting. Do not stop prescribed medicines without advice. A clinician may check your vital signs, blood count, medicines, and digestive symptoms, then arrange further assessment if needed.

Seek emergency help for black stool with dizziness, fainting, weakness, breathlessness, confusion, vomiting blood or material like coffee grounds, severe abdominal pain, or a fast heartbeat. These symptoms may accompany significant blood loss and should not be managed as an IBS flare.

Ask whether the colour could be caused by a medicine or food, whether bleeding needs testing, and which pain relievers are safer for you. Share a description or photograph if the clinician requests it.