What Is Melena?

Melena refers to black, tarry stools that are typically foul-smelling. It occurs when blood from the upper gastrointestinal (GI) tract—such as the esophagus, stomach, or the first part of the small intestine—mixes with digestive juices and is partially digested as it passes through the intestines.

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Why Melena Appears Black

The black color of melena arises from chemical changes that blood undergoes during digestion:

• Hemoglobin breakdown
  Blood contains hemoglobin, a red pigment. In the acidic environment of the stomach, hemoglobin is converted into hematin, which has a dark, almost black color.
• Prolonged transit time
  It takes at least 14–18 hours for blood to travel from the stomach to the rectum. This extended exposure to enzymes and acids deepens the color.
• Tarry consistency
  The mixture of blood, mucus, and digested food produces a sticky, tar-like texture that distinguishes melena from other changes in stool color.

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Common Causes of Melena

Melena is a warning sign that should never be ignored. Some of the most frequent causes include:

• Peptic ulcers
• Gastritis (inflammation of the stomach lining)
• Esophageal varices (swollen veins in the esophagus)
• Mallory-Weiss tears (small tears in the esophagus)
• Tumors in the upper GI tract
• Use of blood-thinning medications (anticoagulants) or non-steroidal anti-inflammatory drugs (NSAIDs)

Less common causes:

• Infections such as Helicobacter pylori
• Rare vascular malformations
• Swallowed blood from a nosebleed or oral trauma

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Why Melena Is Urgent

Although black stool can sometimes result from harmless sources (e.g., certain iron supplements or black licorice), true melena indicates bleeding in the upper GI tract—and that can be serious:

1. Risk of significant blood loss
   • May lead to anemia (low red blood cell count)
   • Can cause weakness, fatigue, and shortness of breath
2. Potential for rapid deterioration
   • Large or uncontrolled bleeds can result in low blood pressure or shock
   • Delay in treatment increases the risk of complications
3. Underlying life-threatening conditions
   • Ulcer perforation or erosion into a blood vessel
   • Ruptured esophageal varices in people with liver disease
   • Malignancies that require prompt diagnosis

Because melena often reflects ongoing bleeding, timely evaluation and treatment are critical.

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Signs and Symptoms to Watch For

Melena may occur alone or alongside other symptoms, such as:

• Abdominal pain or discomfort
• Dizziness or fainting
• Weakness and fatigue
• Rapid heartbeat (tachycardia)
• Low blood pressure (lightheadedness when standing)

If you notice black, tarry stools—especially with any of the above signs—seek medical attention promptly.

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What to Do If You Suspect Melena

1. Track your symptoms
   • Note the onset, frequency, and volume of black stools
   • Record accompanying symptoms (pain, dizziness, etc.)
2. Consider a free, online symptom check, using the doctor approved Ubie Symptom Checker
3. Avoid certain medications until evaluated
   • NSAIDs (ibuprofen, naproxen)
   • Aspirin or other blood thinners
4. Prepare for your medical visit
   • List all medications, supplements, and recent dietary changes
   • Gather a brief medical history (any past ulcers, liver disease, or GI procedures)

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Diagnostic Evaluation

Once you see a healthcare professional, they will likely recommend:

1. Physical examination
   – Checking vital signs (blood pressure, heart rate)
   – Abdominal exam for tenderness or swelling
2. Laboratory tests
   – Complete blood count (CBC) to assess anemia
   – Liver function tests if liver disease is suspected
3. Endoscopy
   – Direct visualization of the esophagus, stomach, and duodenum
   – Ability to treat bleeding sources on the spot (e.g., cauterization)
4. Imaging studies
   – Occasionally, CT angiography to localize active bleeding
   – Nuclear medicine scans for intermittent bleeds

These steps help identify the source of bleeding and guide appropriate treatment.

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Treatment Options

Treatment depends on the cause and severity of bleeding:

• Endoscopic therapy:
– Injection of medications into bleeding vessels
– Thermal coagulation or clipping of bleeding sites

• Medications:
– Proton pump inhibitors (PPIs) to reduce stomach acid
– Antibiotics for Helicobacter pylori infection
– Vasoconstrictors for variceal bleeds

• Surgery or interventional radiology:
– Rarely required if endoscopic methods fail
– Embolization (blocking a bleeding vessel)

• Blood transfusions:
– For significant blood loss and unstable vital signs

Most patients stabilize quickly with prompt care, but follow-up is crucial to prevent recurrence.

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Preventing Recurrence

Once the initial bleeding is controlled, lifestyle and medical strategies can lower the risk of future melena:

• Avoid or limit NSAIDs and alcohol
• Take medications exactly as prescribed
• Treat Helicobacter pylori infections fully
• Manage chronic conditions (e.g., liver disease, coagulopathies)
• Regular follow-up with your gastroenterologist if you’ve had peptic ulcers or varices

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When to Seek Emergency Care

Go to the nearest emergency department or call emergency services if you experience:

• Large-volume black or bloody stools
• Sudden worsening of abdominal pain
• Lightheadedness, fainting, or confusion
• Rapid heart rate or low blood pressure
• Signs of shock (pale, cold, clammy skin)

Melena can herald life-threatening bleeding; urgent evaluation can save lives.

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Final Thoughts

Melena is a clear signal that bleeding is occurring in the upper GI tract. While not every dark stool is melena, any persistent black, tarry stool should prompt medical evaluation. Early diagnosis and treatment greatly improve outcomes. Always speak to a doctor about symptoms that could be life threatening or serious. If you’re unsure what’s causing your symptoms, consider a free, online symptom check, using the doctor approved Ubie Symptom Checker.