This National Institutes of Health Publication 12-5774, "What I Need to Know About Crohn's Disease," provides information on Crohn's disease from understanding the symptoms to obtaining the proper treatment so that you can lead a full, healthy life. Crohn's disease is a disease that causes inflammation, or swelling, and irritation of any part of the digestive tract-also called the gastrointestinal (GI) tract. The part most commonly affected is the end part of the small intestine, called the ileum. Crohn's disease is one of two main forms of diseases of the GI tract named inflammatory bowel disease (IBD). The other form, called ulcerative colitis, affects the large intestine, which includes the colon and the rectum. With Crohn's disease, chronic-or long lasting- inflammation may cause scar tissue to form in the lining of the intestine. When scar tissue builds up, the passage can become narrow, causing food and stool to move through the GI tract more slowly. There are many options for treating Crohn's disease including the proper medicines, diet and nutrition. Most people with Crohn's disease are able to work, raise families, and live full lives.