Soy milk contains vegetable protein, and diarrhea after drinking soy milk in the morning may be due to intolerance to vegetable protein. Diarrhea after drinking soy milk may also be caused by poor gastrointestinal function and incomplete absorption of soy milk into the intestines. In addition, soy milk is a cold food, so if the patient has a weak constitution or a cold spleen and stomach, it may also cause this symptom. If the patient also has abdominal pain, bloating and other symptoms, it may be caused by intestinal diseases such as enteritis. If the patient has no other symptoms, it is recommended that he or she should not drink soy milk on an empty stomach, but with hot foods such as doughnuts and buns. If it is accompanied by other symptoms, you should go to the hospital early for relevant examination and targeted treatment.