Melena is the presence of digested blood in the stool, marked by very dark, tar-like stools with a strong odor, abdominal pain, or even vomiting blood.

This usually happens due to bleeding in the upper digestive tract, such as the mouth, esophagus, or stomach, as in cases of stomach ulcers or erosive esophagitis. It can also result from swallowing blood after a nosebleed or coughing up blood.

It is important to see a gastroenterologist or general practitioner whenever dark stools appear, so tests can be done to identify the cause and begin proper treatment if needed, helping to prevent complications.

Symptoms of melena

The main symptoms of melena are:

Dark, tar-like stools
Black, foul-smelling stools
Abdominal pain
Indigestion

In some cases, other symptoms may include fatigue, weakness, fainting, difficulty swallowing, or vomiting blood. If left untreated, melena can lead to complications such as anemia, loss of consciousness, and even multi-organ failure.

For this reason, it is essential to consult a gastroenterologist or general practitioner whenever symptoms of melena occur, so treatment can be started promptly.

Main causes of melena

The main causes of melena are:

1. Stomach ulcer

A stomach ulcer is a sore that forms on the stomach lining and can cause bleeding. Depending on the amount of blood released, stools may become very dark and foul-smelling. Ulcers are more common in people with chronic gastritis and are usually accompanied by other symptoms, such as severe stomach pain after eating, persistent nausea, and vomiting.

What to do: Treatment is prescribed by a gastroenterologist and typically involves medications that reduce stomach acid, such as omeprazole, esomeprazole, or antacids, to help ulcers heal. Dietary changes are also an important part of treatment.

2. Esophageal varices

Esophageal varices are enlarged veins in the esophagus that can rupture and bleed into the digestive tract, leading to very dark, foul-smelling stools. Other symptoms include vomiting bright red blood, paleness, and severe fatigue.

This condition is most common in people with liver disease, which increases pressure in the veins of the digestive system and causes them to dilate.

What to do: Immediate medical care is required, as ruptured esophageal varices are a life-threatening emergency that usually requires surgery to stop the bleeding. Ongoing treatment as directed by a doctor is also necessary to prevent recurrence.

3. Gastritis

Gastritis is inflammation of the stomach lining. While it often does not cause bleeding, untreated gastritis can irritate the lining enough to cause small bleeds, leading to melena. Other symptoms may include stomach pain, heartburn, general discomfort, and vomiting, especially after eating.

What to do: Gastritis treatment is managed by a gastroenterologist with medications such as omeprazole or esomeprazole. If melena is suspected, a medical evaluation is important, since bleeding may also indicate a developing ulcer.

Check-out some home remedies for gastritis that can be prepared to complement your treatment.

4. Erosive esophagitis

Erosive esophagitis is inflammation, irritation, or swelling of the esophagus lining, which can cause sores that bleed and result in melena. Other symptoms may include vomiting blood, chest pain, heartburn, or throat pain when swallowing.

This condition is usually caused by frequent acid reflux or untreated esophagitis, as stomach acid rising into the esophagus can damage the lining.

What to do: Treatment should be guided by a gastroenterologist to prevent lesions and bleeding. In cases of bleeding, treatment in the hospital may include intravenous proton pump inhibitors and surgery to stop the hemorrhage.

5. Mallory-Weiss syndrome

Mallory-Weiss syndrome occurs when small tears develop in the esophagus due to excess pressure, often after repeated or forceful vomiting. These tears can rupture blood vessels, leading to bleeding and melena. Common symptoms include vomiting blood, pain in the upper stomach, extreme fatigue, dizziness, or fainting.

What to do: Hospital evaluation is recommended to stop the bleeding and begin treatment. In more severe cases, surgery may be needed to repair the tears.

6. Stomach cancer

Although less common, stomach cancer can cause melena due to bleeding in the stomach lining. Other signs and symptoms may include unexplained weight loss, persistent heartburn, loss of appetite, feeling full after eating small amounts, and severe weakness.

What to do: Any suspicion of stomach cancer should be evaluated by a gastroenterologist as soon as possible. Early detection improves treatment success. Most cases are treated by an oncologist with chemotherapy and radiation therapy, and surgery may be necessary to remove the affected part of the stomach.

7. Medication use

Certain medications can irritate or damage the digestive tract and cause melena, including:

Nonsteroidal anti-inflammatory drugs (NSAIDs) like aspirin, ibuprofen, and naproxen
Bisphosphonates such as alendronate
Antibiotics such as tetracycline, clindamycin, or doxycycline
Iron supplements (ferrous sulfate)
Potassium chloride supplements

What to do: Go to the hospital for evaluation and treatment, which may involve medications or surgery to stop the bleeding. The doctor may also adjust or replace the medication responsible and prescribe stomach protectors if necessary.

Difference between melena and hematochezia

Both melena and hematochezia result from gastrointestinal bleeding, but they differ in where the bleeding occurs and how the stool appears.

In melena, bleeding occurs in the upper digestive tract, such as the stomach, mouth, esophagus, or duodenum. Because the blood is digested as it passes through the intestines, stools appear dark and tar-like.

In hematochezia, bleeding occurs in the lower digestive tract, such as the small intestine, colon, rectum, or anus, resulting in bright red blood in stool.

Melena: Symptoms, Causes & What to Do