What is dark stool?
Darkening of the stool may be a normal occurrence related to specific foods or medications; however, it can sometimes be a sign of a more serious condition such as bleeding in the intestinal tract. When related to foods, blueberries, beets, or black licorice are often the cause. Stool passed after eating these foods may be dark brown, bluish, reddish, or black. Iron supplements and medications containing bismuth subsalicylate, a common ingredient in anti-diarrhea medications, can also turn the stool dark or black.
Dark stool not associated with specific foods or medications can be more worrisome and may be an indicator of bleeding somewhere in the digestive system. The color and quality of the stool depends on where the bleeding is occurring and how fast the stool moves through the digestive system. Blood from the esophagus, stomach, and small intestine may have time to be metabolized as it transits, which can result in black stool that may have a tarry consistency (melena).
Bright red blood in the stool frequently comes from the lower portion of the digestive tract, specifically the colon or anus. It has not been metabolized and so it preserves a bright red appearance (hematochezia). At the same time, bleeding from higher up can speed digestive transit times, so bright red blood does not rule out bleeding from the esophagus, stomach, or small intestine. Red striping of the stool is often related to bleeding near the exit of the digestive tract and may be seen with hemorrhoids.
Since dark stool can be related to digestive tract bleeding, if it cannot be explained by a specific food or medication, dark stool should be immediately evaluated in an emergency setting. Seek immediate medical care (call 911) for bloody stool or stool that is black or tarry in consistency that is accompanied by profuse sweating, changes in level of consciousness, rapid heartbeat (tachycardia), severe abdominal pain, vomiting blood, or chest pain.
If your dark stool is persistent or causes you concern or if you have pain with bowel movements, seek prompt medical care.
What other symptoms might occur with dark stool?
The symptoms of dark stool are generally related to food or medications that pass through the digestive tract or something more serious such as digestive tract bleeding.
Digestive symptoms that may occur along with dark stoolDark stool may accompany other symptoms affecting the digestive tract including:
What causes dark stool?
Dark stool may be caused by foods or medications by bleeding within the digestive tract.
Food and medication causes of dark stoolDark stool may be caused by foods or medications including:
- Black licorice
- Iron supplements
- Medications containing bismuth subsalicylate (for examp... Read more about dark stoolcauses