The symptoms of functional bowel disorders include abdominal pain, feeling full soon into a meal, nausea, bloating, distention, are characterized by recurrent gastrointestinal symptoms that have no identifiable structural or biochemical basis. Symptoms include abdominal pain, feeling full soon into a meal, nausea, bloating, distention, and various symptoms of disordered defecation. The three most common functional bowel disorders are irritable bowel syndrome (IBS), constipation, and functional dyspepsia (indigestion).