What are the causes of black diarrhea?

Once an individual passes out black diarrhea, it is often an indication of the presence of blood in the digestive tract that has various causes depending on the exact areas where the blood originates. The gastrointestinal tract is usually present as blood in the stool more than as black diarrhea. It is important to note that black diarrhea due to bleeding is known as melena. Other possible causes include certain medications, foods and toxins. If the bleeding is severe, emergency care is vital.


There are certain foods that can cause black diarrhea such as dark colored vegetables and fruits particularly blackberries, blueberries and beets. Even desserts such as black pudding and black licorice can also cause black diarrhea as well as bloody meats.

Supplements and medications

Supplements such as iron that is given for iron deficiency anemia as well as other conditions involving low iron can also be considered as a source of black diarrhea. Even charcoal can cause this symptom which is oftentimes administered in order to treat ingestion of certain toxins since it can bind to some drugs in the gastrointestinal tract. Other medications such as Maalox which is a gastrointestinal medication can also cause black diarrhea.

Black diarrhea

The development of ulcers in the stomach is likely to bleed.


It is important to note that the toxic mineral lead can also be considered as one of the causes of black diarrhea. Take note that the usual cause of lead poisoning is exposure to lead paints, particularly in older houses.

Gastrointestinal bleeding

The development of ulcers in the stomach is likely to bleed. Even stomach acid, infections and certain cancers are also sources of ulcers. Angiodysplasia which is the malformation of blood vessels can bleed and result to melena. Additionally, gastritis or the general inflammation of the stomach can also be considered as a cause but it is a rare source of bleeding.

Oral, nasal and esophageal bleeding

Rapid bleeding from the oral or nasal cavity can end up swallowed into the gastrointestinal tract and cause melena. There are various sources of bleeding that occurs in the esophagus. The inflammation or development of ulcers can be due to infections or acid reflux into the esophagus from the stomach.

A tear in the esophagus due to vomiting and retching after drinking large amounts of alcohol can also cause bleeding. In some cases, esophageal varices are the dilated veins in the esophagus which usually form due to liver cirrhosis. Take note that they are dangerous since they can lead to rapid bleeding into the gastrointestinal tract.

Bleeding in the small intestines

The small intestine can also develop ulcers, especially in the duodenum which is the initial part of the small intestine close to the stomach. Bacterial infections especially with the Helicobacter pylori are the usual cause of duodenal ulcer.

In some cases, Meckel’s diverticulum can develop in the lower part of the small intestines. Lastly, a condition that can also cause bleeding in the small intestine that leads to the black diarrhea is Crohn’s disease. This is an inflammatory disease that can occur all over the GI tract in which the lesions erode the tissues of the bowel wall.


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