Inflammatory bowel disease (IBD) is a term for two conditions (Crohn’s disease and ulcerative colitis) that are characterized by chronic inflammation of the gastrointestinal (GI) tract. Prolonged inflammation results in damage to the GI tract. What are the common symptoms of IBD? Persistent diarrhea. Abdominal pain. Rectal bleeding/bloody stools. Weight loss. Fatigue. What causes IBD? The exact cause of IBD is unknown, but IBD is the result of a weakened immune system. Possible causes are: The immune system responds incorrectly to environmental triggers, such as a virus or bacteria, which causes inflammation of the gastrointestinal tract. There also appears to be a genetic component. Someone with a family history of IBD is more likely to develop this inappropriate immune response.