When drinking milk, feeling nausea may be related to the lack of lactase enzyme in the body or suffering from gastric problems. 1. Lack of lactase: due to the lack of lactase in the human body, after drinking milk due to the lactose in the milk can not be properly absorbed and digested, it may cause a large number of bacterial reproduction in the gastrointestinal tract, which in turn causes excessive gastric acid, vomiting and other symptoms. 2. Stomach diseases: such as gastric ulcer, gastritis patients, if you drink milk on an empty stomach, there may be nausea and want to vomit. In addition, it is recommended to drink milk gradually, avoid drinking too much at once. It is best to eat some staple food before drinking milk, do not drink milk on an empty stomach, can be conducive to digestion. There are many other causes of nausea when drinking milk, if the symptoms are serious, or continue to see no improvement, it is recommended to go to the regular hospital in a timely manner, to clarify the cause of the disease, under the guidance of the doctor for targeted treatment.