Overview of Crohn's Disease



Crohn’s disease is a chronic inflammatory condition of the gastrointestinal tract. Understanding Crohn’s disease can help you and your loved ones navigate the uncertainty that comes with a new diagnosis.

Calling all Crohn’s patients! Have you or a loved one been recently diagnosed? Or were you diagnosed with Crohn’s disease years ago but still don’t fully understand your disease? Check out our latest video chat to learn more.


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Video Chat: Crohn's Disease 101


Crohn’s disease belongs to a group of conditions known as inflammatory bowel diseases, or IBD. It is named after Dr. Burrill B. Crohn, who first described the disease in 1932 along with his colleagues, Dr. Leon Ginzburg and Dr. Gordon D. Oppenheimer.


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Crohn's 101 - Overview This introductory video provides information on potential causes, symptoms, treatment and overall management of Crohn’s disease.

Who is Affected?

  • Nearly 1 in 100 Americans are diagnosed with IBD. Men and women are equally likely to be affected by Crohn's disease.

  • The disease can occur at any age, but Crohn’s disease is most often diagnosed in adolescents and adults between the ages of 20 and 30.

  • Studies have shown that between 1.5 percent and 28 percent of people with IBD have a first-degree relative, such as a parent, child, or sibling, who also has one of the diseases.

  • Even though there is genetic component associated with increased risk of IBD, it is impossible to predict who may get Crohn’s disease based on family history.

  • Crohn’s disease can affect people from all ethnic backgrounds. The disease is more common in Caucasians, though the rates of Crohn’s disease have increased among Hispanics and Asians in recent years.

Crohn’s Disease

  • Can affect any part of the GI tract from the mouth to the anus, but most commonly affects the end of the small bowel (ileum) and the beginning of the colon

  • Can affect the entire thickness of the bowel wall

  • Inflammation of the intestine can “skip,” or leave normal areas in between patches of diseased intestine

Ulcerative Colitis

  • Only the colon, also called the large intestine, is affected

  • Affects only the innermost lining of the colon

  • Inflammation of the intestine does not “skip”

Types of Crohn’s Disease

If you are diagnosed with Crohn’s disease, it’s important to know which part of your GI tract is affected. While symptoms of Crohn’s disease can vary from person to person, the type of Crohn’s you have impacts the symptoms and complications you may experience.


This is the most common form of Crohn’s disease. It affects the end of the small intestine, known as the terminal ileum, and the large intestine, also called the colon.

Symptoms may include:

  • Diarrhea and cramping

  • Pain in the middle or lower right part of the abdomen

  • Significant weight loss


This type of Crohn’s affects only the ileum.

Symptoms may include:

  • Same as ileocolitis

  • In severe cases, complications may include fistulas or inflammatory abscess in the right lower quadrant of the abdomen

Gastroduodenal Crohn's Disease

This type affects the stomach and the beginning of the small intestine, called the duodenum.

Symptoms may include:

  • Nausea

  • Vomiting

  • Loss of appetite

  • Weight loss


This type is characterized by patchy areas of inflammation in the upper half of the small intestine, called the jejunum.

Symptoms may include:

  • Mild to intense abdominal pain and cramps following meals

  • Diarrhea

  • Fistulas may form in severe cases or after prolonged periods of inflammation

Crohn's (Granulomatous) Colitis

This type affects only the colon, also known as the large intestine.

Symptoms may include:

  • Diarrhea

  • Rectal bleeding

  • Disease around the anus, including abscess, fistulas and ulcers

  • Skin lesions and joint pains are more common in this form of Crohn's than in others

Crohn’s Disease vs. Ulcerative Colitis

Crohn’s disease and ulcerative colitis share similar symptoms and they are both types of inflammatory bowel disease (IBD), but they are not the same illness and they affect different areas of the GI tract.

Crohn's disease

  • Can affect any part of the GI tract from the mouth to the anus
  • Can affect the entire thickness of the bowel wall

Ulcerative colitis

  • Only the colon and rectum (also known as the large intestine) are affected
  • Affects the inner-most lining of the large intestine


Related Resources


Living with Crohn's Disease...

A brochure to help patients and their caregivers learn about how to manage Crohn’s disease.