There are many reasons for diarrhea caused by drinking milk, mainly related to the following factors: 1, some patients have lactose intolerance, that is, the lack of lactase in the body, which is an important reason for common diarrhea caused by drinking milk, especially infants and children are most likely to have lactose intolerance, milk is rich in lactose, so it is also the most likely to cause lactose intolerance and diarrhea food. 2, patients have allergies. Some patients are allergic themselves, and drinking milk can also cause allergies and thus diarrhea symptoms. Therefore, you can go to the hospital for allergen testing, and if you are indeed allergic to milk, it is recommended not to drink milk, which can cause diarrhea and even blood in the stool. 3, milk itself is a type of food that stimulates the gastrointestinal tract to secrete gastric acid, and if there are digestive system diseases, such as peptic ulcer and chronic gastritis, drinking milk may increase the secretion of gastric acid, which may lead to stomach pain, or even Therefore, if the patient is suffering from active gastric disease, it is recommended to avoid drinking milk for the time being. There are also some patients who have a weak spleen and stomach, and drinking milk without adequate heating can also lead to a cold abdomen, resulting in diarrhea, which is often seen after drinking milk diarrhea.