Drinking pure milk and then diarrhea, the main consideration of lactose intolerance, the patient’s allergy to milk, milk is too cold and other factors. 1. Lactose intolerance: when the patient’s body lacks lactase enzyme or lactase enzyme content is too small, lactose intolerance will occur, drinking pure milk diarrhea. 2. Allergy: When the patient has an allergic reaction to milk and other dairy products, there will also be diarrhea, nausea, vomiting, skin rash and other reactions after drinking pure milk. 3. Milk is too cold: when the patient drinks milk that has just been taken out of the refrigerator or is too cold, the cold accelerates the stimulation of the gastrointestinal tract, and diarrhea can also occur after drinking pure milk. In addition, drinking pure milk on diarrhea, there may be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.