Why is my stool black?
Disease description:
This morning when I went to the bathroom, I noticed that my stool was blackish red. What could be causing this? I don't have any other uncomfortable symptoms, though.
Doctor's answer (1)
Dr. Shen Yonghua
Black stool, commonly referred to as tarry stool or melena, can be caused by the following factors:
1. Diet: Consuming excessive amounts of iron-rich foods, such as pig's blood, duck's blood, and pork liver. The iron in these foods can form black ferrous sulfide through bacterial action in the intestines, causing the stool to darken.
2. Medications: Taking medications such as iron supplements, bismuth preparations, certain traditional Chinese medicines, and activated charcoal may cause darkening of the stool. This is due to either the color of the medication itself or chemical reactions occurring within the intestines.
3. Medical conditions: Gastrointestinal bleeding is a common pathological cause of black stool. When there is bleeding in the upper gastrointestinal tract, iron from the blood forms iron sulfide under the action of intestinal bacteria, resulting in black-colored stool. This type of stool is typically referred to as melena.
4. Other factors: Constipation may also lead to darker stool because when feces remain in the intestine for an extended period, excessive water absorption causes the stool to become dry and concentrated.
If black stool persists or is accompanied by other symptoms, prompt medical attention should be sought.
