Black stool for three days: what to know

A colour change can follow iron, bismuth-containing medicine, or dark foods. That explanation is more plausible when the stool is formed and you otherwise feel well. Black, shiny, sticky stool with a strong smell is different and can reflect blood altered during digestion. Causes may include gastritis, Helicobacter pylori infection, or a peptic ulcer. Three days of symptoms is enough reason to contact a clinician rather than relying on colour alone.

Make a list of medicines, supplements, foods, and symptoms from the time the change began. Contact a healthcare professional today for advice about an examination and possible blood or stool testing. Do not stop essential prescribed treatment without guidance. Avoid anti-inflammatory painkillers and alcohol until a clinician has reviewed the situation, and keep hydrated if you are losing fluid.

Attend urgent care immediately if you feel faint, unusually weak, breathless, confused, or clammy; vomit blood or dark granular material; develop severe abdominal pain; or continue passing black tarry stool. These symptoms can accompany significant digestive bleeding. Do not drive yourself if you feel faint. Bring medication packaging if it is readily available.

Ask whether the appearance is consistent with melaena, whether a medicine or supplement could explain it, and which tests are appropriate. Share any abdominal pain, indigestion, previous ulcer, vomiting, dizziness, or change in bowel habits.