What Is It?
Crohn's disease is an inflammatory bowel disease in which inflammation injures the intestines. It is a long-term (chronic) condition. Crohn's disease typically begins between ages 15 and 40.
No one knows for sure what triggers the initial intestinal inflammation at the start of Crohn's disease. A viral or bacterial infection may start the process by activating the immune system. The body's immune system stays active and creates inflammation even after the infection goes away.
Certain genes passed on from parent to child may increase risk of developing Crohn's disease if the right trigger occurs.