Bloating and Dark Stool: What to Know

Dark brown stool can reflect normal variation, but black stool that looks tarry, sticky, or unusually foul-smelling is different. Iron supplements, bismuth-containing medicines, and strongly pigmented foods can also darken stool. Bloating may occur alongside constipation, food intolerance, or an upper digestive problem, but it does not explain away black stool.

Do not try to diagnose the cause from colour alone. Note when the change began, its texture, medicines and supplements, abdominal symptoms, and any dizziness or weakness.

If the stool is black and tar-like, contact a medical service promptly rather than waiting for bloating to settle. Take or list your medicines and supplements, and avoid taking anti-inflammatory pain medicines unless a clinician has advised them. Do not stop prescribed treatment without guidance.

If a food or medicine may explain a dark colour, still seek advice when the change persists, recurs, or is accompanied by pain, vomiting, or unusual tiredness.

Go to urgent care immediately for black tar-like stool with faintness, confusion, severe weakness, rapid heartbeat, vomiting blood or material that resembles coffee grounds, severe abdominal pain, or repeated dark stools. These signs can indicate significant bleeding or another urgent problem.

Ask whether your stool appearance could be caused by a medicine or bleeding, whether blood tests or other tests are needed, and which symptoms mean you should return urgently.