This is a disease of chronic inflammation involving any part of the intestinal tract. It most commonly affects the last part of the small intestine (ileum) and/or the large intestine (colon and rectum). It is relatively uncommon in the Asian population.

Crohn's disease is a chronic condition and may recur at various times over a lifetime. Some people have long periods with no disease, sometimes years, when they are free of symptoms. There is no way to predict when the disease can come back.