What is Crohn's disease?

Crohn's disease is a chronic (long-term) illness in which the intestine (bowel) becomes inflamed and ulcerated (marked with sores). Along with ulcerative colitis, Crohn's disease is part of a group of diseases known as inflammatory bowel disease (IBD).

Crohn's disease most commonly affects the lower part of the small intestine (ileum), although it can occur in any part of the large or small intestine, stomach, esophagus (“food pipe”), or even the mouth. It can occur at any age, but it is most common between the ages of 15 and 30.

Crohn's disease can interfere with the normal function of the bowel in a number of ways. The bowel tissue may:

  • Swell, thicken, or form scar tissue, which can lead to blockage of the passageway inside the bowel.
  • Develop ulcers that can involve the deep layers of the bowel wall.
  • Lose its ability to absorb nutrients from digested foods (malabsorption).
  • Develop abnormal passageways (fistulas) from one part of the bowel to another part of the bowel, or from the bowel to nearby tissues such as the bladder or vagina, or even the skin.

What causes Crohn's disease?

The cause of Crohn's disease is unknown. It is believed that many factors cause an abnormal response of the immune system in the gastrointestinal tract.

Genetics (heredity) has been found to play a role in the disease process. First-degree relatives (mother, father, sister, or brother) of patients with IBD are about three to 20 times more likely to develop the disease than the general population. Having a sibling with Crohn's disease can increase the risk of having the disease by 30 times compared with the general population. Children who have one parent with Crohn's disease, and Jewish people of European descent, also have a greater risk for developing the disease.

What are the symptoms of Crohn's disease?

People with Crohn's disease go through periods of severe symptoms followed by periods of remission (no symptoms, or milder symptoms) that can last for weeks or years. Unfortunately, there is no way to tell when a remission will occur or when symptoms will return.

The symptoms of Crohn's disease depend on where in the bowel the disease occurs and how severe it is. In general, symptoms can include:

Other symptoms can develop, depending on the complications of the disease. For example, a person with a fistula (abnormal passageway) in the rectal area may have pain and discharge around the rectum. Other complications from Crohn's disease include:

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