Crohn's disease is a type of inflammatory bowel disease (IBD) that may affect any part of the gastrointestinal tract. Signs and symptoms often include abdominal pain, diarrhea, fever, and weight loss, and possible bowel obstruction. Other complications may occur outside the gastrointestinal tract and include anemia, skin rashes, arthritis, and tiredness. Crohn's disease is caused by a combination of environmental, immune and bacterial factors in genetically susceptible individuals. It results in a chronic inflammatory disorder, in which the body's immune system attacks the gastrointestinal tract possibly directed at microbial antigens.