Toilet paper

Black Stool


Healthgrades Editorial Staff

What is black stool?

Black stool is a condition in which the feces are very dark or black in color. Black stool may be normal in some cases and caused by ingesting certain substances or medications, such as iron supplements. However, black stool can also be caused by a serious condition, such as bleeding in the digestive tract caused by a peptic ulcer.

Black stool that is tarry in texture and foul smelling is often a symptom of upper gastrointestinal bleeding from the esophagus, stomach or small intestine. This is called melena. Rectal bleeding of bright red blood with clots, sometimes mixed with stool, is called hematochezia. Hematochezia is often caused by bleeding from the lower digestive tract, including the colon, rectum or anus.

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Very small amounts of blood in the stool may be seen by the naked eye and not significantly change the color of stool. This is called fecal occult blood, which can be a symptom of a serious disease and may be found with regular, routine medical testing.

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Black stools can be a symptom of a serious condition, such as esophageal varices or peptic ulcer. Seek prompt medical care if you have unusually dark stools or any change in the color or texture of your stool. If your stools are black and tarry in texture, bloody, or if you have major rectal bleeding, seek immediate medical care (call 911).