The common primary symptoms of lactose intolerance are gastrointestinal include abdominal pain, diarrhea and flatulence, better known as passing gas. Less common symptoms of lactose intolerance include abdominal bloating, abdominal distention, nausea. Nausea is the sensation that there is a need to vomit. Nausea can be acute and short-lived, or it can be prolonged. When prolonged, it is a debilitating symptom.