In rare cases, it appears once or twice and does not ever return. If the disease continues for many years, bowel function gradually deteriorates. It may increase the risk of cancer by as much as twenty times. When the large intestine is involved, chronic bleeding often occurs which may lead to anemia, and after years increases the risk of colon cancer. If the ulcerated intestinal wall leaks, peritonitis can result.
Perforation is rare.
Mouth and anal sores often are present in about many when the disease is active. Strictures can occur that partially block the bowel. About a third of those with the disease, develop cracks in the lining of the mucus membrane around the anus. Inflammation with pain and tenderness in the right lower abdomen. Recurring acute intestinal obstructions that cause severe spasms of the intestinal wall, swelling of the abdomen, constipation, and vomiting.