Gastrointestinal (GI) disease is any disorder that affects the digestive tract, which includes the esophagus, stomach, small intestine, large intestine, rectum, and anus. Common GI diseases include irritable bowel syndrome (IBS), gastroesophageal reflux disease (GERD), peptic ulcer disease, inflammatory bowel disease (IBD), and celiac disease. Symptoms of GI diseases can include abdominal pain, diarrhea, nausea, vomiting, and constipation. Treatment for GI diseases depends on the specific condition and may include dietary changes, medications, and/or surgery.