Black stool is not necessarily gastric bleeding, only that there is a possibility of gastric bleeding, leading to black stool for a number of reasons, such as the impact of food, drugs and upper gastrointestinal bleeding. 1. The influence of food: for example, eating some iron-rich food can also cause black stool color, such as chicken blood, duck blood, pig liver, dark green vegetables, etc., can be due to the reaction of iron and sulfide in the intestinal tract. 2. Drugs: the intake of some drugs containing iron, can also lead to black stool, also for iron and intestinal sulfide reaction. 3. Upper gastrointestinal bleeding: for example, when the stomach, esophagus and other parts of the bleeding, the iron in the red blood cells and intestinal sulfide reaction, resulting in black stool phenomenon. There are many other reasons that can lead to the phenomenon of black stool, it is recommended that such patients go to a regular hospital, consult a professional doctor, and cooperate with the doctor to complete the relevant examination, to clarify the cause, to avoid blind treatment.