Black particles in stools are usually caused by dietary factors, medication and gastrointestinal bleeding. 1. Dietary factors: for example, after consuming black sesame, black fungus, black mushroom or pig’s blood, duck’s blood, cow’s blood, etc., with the digestion and excretion of the food, it can make the feces with black particles, which is a normal phenomenon, and after stopping the consumption of the food, the feces can be returned to normal. 2. Drug factors: when taking drugs such as ferrous sulfate, it will combine with hydrogen sulfide in the intestine and oxidized to trivalent iron, which will cause black particles in the stool, and the color of the stool will be back to normal after stopping the drug for 3 to 5 days. 3. Gastrointestinal bleeding: mainly related to peptic ulcer, esophageal disease, biliary bleeding and other factors. Research shows that when the daily bleeding exceeds 50ml, there can be black stool symptoms, i.e., black particles in the stool, it is recommended to go to the hospital immediately for examination to clarify the cause of the disease and then treat the symptoms. If you have black particles in your stool with other symptoms, it is recommended that you seek medical attention and follow the doctor’s instructions.