• Fistula formation: An abnormal connection between the intestines and skin/organs or between the intestines is called as fistula.
• Perforation: Free perforation occurs in 1 to 2% of patients, usually in the ileum but occasionally in the jejunum or as a complication of toxic megacolon.
• Peritonitis: Peritonitis of free perforation, especially colonic, may be fatal. Generalized peritonitis may also result from the rupture of an intra-abdominal abscess.
• Intestinal obstruction: The inflammation causes the intestines to thicken and over the period of time narrows completely. There is 40% chance of developing Intestinal Obstruction.
• Massive hemorrhage: Ulcers in intestines may bleed profusely.
• Mal-absorption: It causes low protein, low calcium, and low magnesium in body. Also it leads to formation of renal and gall stones.
• Severe peri-anal disease: Crohn's Disease. causes anal strictures, ano-rectal fistulae, and abscesses.
• Colon Cancer: In patients with extensive colonic involvement, the overall risk of developing colon cancer is 18-fold and the cumulative risk is 8% at 22 years.
• About 80% of people with Crohn's will require surgery in order to relieve their symptoms and repair damage to their digestive system.