Dark Black Tarry Stools (Melena)
How doctors evaluate dark black tarry stools (melena) — persistence, progression, common non-cancerous causes, and when to consult a doctor.
Quick Answer: What You Need to Know
This symptom is very common and is vastly more likely to be caused by a benign, non-cancerous condition. However, if it is persistent (lasting longer than 2 to 4 weeks) or progressive (getting steadily worse), you should have it evaluated by a healthcare professional.
Get emergency care now
Go to an emergency department now if your stools are black and tarry. Call emergency services rather than driving if you also feel faint, dizzy or confused, have a racing heart, are breathing fast, have cold clammy or pale skin, have vomited blood or coffee-ground material, or have severe abdominal pain. Do not wait to see whether it happens again.
🔍 How Doctors Evaluate This Symptom
Most symptoms are far more commonly caused by benign, non-cancerous conditions. When a change in your body is being assessed, two things matter most:
There is no watch-and-wait period for melena. Stools that are black, sticky and tarry with a strong distinctive smell usually mean digested blood from the stomach or upper bowel, and this needs urgent same-day assessment even after a single episode — do not wait weeks. Iron tablets, bismuth medicines, black liquorice and blueberries can darken stool without it being blood, but assume bleeding and get checked rather than deciding this yourself.
The dangerous direction is more frequent tarry stools, the appearance of vomited blood or coffee-ground material alongside them, or signs that you are losing blood volume: light-headedness on standing, a fast heartbeat, breathlessness on mild effort, sweating, and fainting.
Most melena comes from a peptic ulcer in the stomach or duodenum, erosive gastritis, oesophagitis, or bleeding oesophageal varices in people with liver disease. Aspirin, ibuprofen and similar anti-inflammatory painkillers, steroids and anticoagulants substantially increase the risk of these bleeds.
Representative Scenario: Evaluating Dark Black Tarry Stools (Melena)
An individual notices dark black tarry stools (melena) and schedules an evaluation with their doctor to review their health history.
Common Non-Cancerous Causes
Before considering rare explanations, healthcare providers first check for common benign causes, such as:
Most melena comes from a peptic ulcer in the stomach or duodenum, erosive gastritis, oesophagitis, or bleeding oesophageal varices in people with liver disease. Aspirin, ibuprofen and similar anti-inflammatory painkillers, steroids and anticoagulants substantially increase the risk of these bleeds.
When Cancer May Be Considered
Doctors consider cancer as a possibility primarily when a symptom is persistent (does not resolve after 2–4 weeks of standard care), progressive (steadily worsening), or accompanied by associated changes like unexplained weight loss, fever, night sweats, or a hard lump.
Details That Matter to Your Doctor
- Exact date when you first noticed the change.
- Whether the symptom is constant or comes and goes.
- Whether anything makes the symptom better or worse.
- Any family history of similar health conditions.
What NOT to Do
- Do not repeatedly self-treat a persistent symptom with over-the-counter remedies without getting evaluated.
- Do not attempt to self-diagnose using online images or automated symptom checking quizzes.
- Do not assume a symptom is harmless simply because it is painless.
- Do not delay emergency care if you experience severe shortness of breath or heavy bleeding.
What a Clinician May Ask or Examine
Your doctor will take a medical history, perform a physical exam, review medications, and order targeted blood work or imaging scans if needed to clarify the cause.
Prepare for Your Doctor Visit
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This guide is based on official guidance published by the National Cancer Institute ↗