There is a certain diarrhea when drinking coffee on an empty stomach: first, there is a certain amount of caffeine in coffee, caffeine is absorbed and digested in the body to make the intra-abdominal pressure osmotic increase, at this time will produce osmotic diarrhea, watery stool situation. Therefore, it is not recommended to drink coffee or black coffee on an empty stomach, because it will lead to the presence of long-term diarrhea. Second, drinking coffee without sugar or milk, simply drinking coffee concentration is too strong or cocoa concentration is too strong, will also lead to the aggravation of diarrhea, because coffee contains some cocoa butter ingredients, will lead to abnormal increase in gastrointestinal peristalsis, so it will trigger the diarrhea situation. Third, the original underlying disease such as acute gastroenteritis can not drink coffee, drinking coffee will make the diarrhea situation aggravated.