Vomiting and Nausea
Among other symptoms, the intestinal discomfort can also make its way up to cause irritation of the stomach. This is generally perceived as nausea. There is a strong urge to vomit in people with lactose intolerance.
In severe cases, the stomach contents are expelled by a process called reverse peristalsis. In most of the cases, it usually happens after eating or drinking a Dairy product.