Digestive Diseases: Crohn's Disease

Last Editorial Review: 2/17/2006


Crohn's disease is a chronic illness of children and adults in which the intestines (bowel) become inflamed. The disease affects the full thickness of the intestinal wall and this inflammation can lead to serious complications that may require surgery. The condition typically affects the lower part of the small intestine (ileum), although it can occur in any part of the gastrointestinal tract from the mouth to the anus. Sections of diseased bowel can be interrupted by sections of healthy bowel. Crohn's disease can disrupt the normal function of the bowel in a number of ways, causing the tissue to:

  • Swell and thicken, narrowing or blocking the passageway inside the bowel.
  • Develop ulcers that involve the deep layers of the wall of the bowel.
  • 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 a nearby organ.

When grouped together, Crohn's disease and ulcerative colitis are referred to as inflammatory bowel diseases (IBD) because they cause inflammation of the bowel (intestines).

What Are the Symptoms of Crohn's Disease?

People with Crohn's disease can experience periods of severe symptoms followed by periods of remission that can last for weeks or years. The symptoms of Crohn's disease depend on where the disease occurs in the bowel and its severity. In general, symptoms can include:

Other symptoms can develop, depending on complications related to the disease. For example, a person with a fistula (abnormal passageway between various organs or tissues) in the rectal area may have pain and leaking discharge around the rectum.

Severe inflammation and obstruction of various parts of the gastrointestinal tract due to swelling and scar formation can cause other problems like bowel perforation, abdominal distension (swelling), severe pain, and fever. This can be life-threatening.

Also, because Crohn's disease is an autoimmune disease (see below), other parts of the body can become inflamed including the joints, eyes, mouth and skin. In addition, gallstones, and kidney stones may also develop as a result of Crohn's disease.

Moreover, children with the disease may experience decreased growth or delayed sexual development.

What Causes Crohn's Disease?

The cause of Crohn's disease is unknown. However, it is likely due to an abnormal response of the immune system. Food or bacteria in the intestines, or even the lining of the bowel may cause the uncontrolled inflammation associated with Crohn's disease.

Who Gets Crohn's Disease?

Crohn's disease is often inherited. About 20% of people with Crohn's disease may have a close relative with either Crohn's or ulcerative colitis. In addition, Jewish people of European descent (Ashkenazi) are at greater risk for the disease.

While Crohn's disease can affect people of all ages, it is primarily an illness of the young. Most people are diagnosed before age 30, but the disease can occur in people in their 60's, 70's or later in life.

How Is Crohn's Disease Diagnosed?

A variety of diagnostic procedures and laboratory tests are used to distinguish Crohn's disease from other inflammatory gastrointestinal conditions like ulcerative colitis.

First, your doctor will review your medical history. A specialist called a gastroenterologist may perform a colonoscopy or sigmoidoscopy to obtain bowel tissue for analysis. Other tests your health care provider may order include:

  • Blood tests, including blood counts (often high white blood cell counts -- a sign of inflammation -- and low red blood cells counts a sign of anemia from blood loss -- are present).
  • Stool samples to rule out infections as the cause of diarrhea.
  • Special X-ray of both the upper and lower GI tract may be ordered as well to confirm the location of the inflammation.

Grades of Crohn's Disease

According to the American College of Gastroenterology, Crohn's disease activity is characterized as:

  • Mild-moderate disease: Being able to eat with no evidence of dehydration, severe illness (fevers, significant weight loss, abdominal pain, nausea, vomiting) or severe anemia.
  • Moderate-severe disease: Those who have failed to respond to treatment for mild-moderate disease or those with fevers, weight loss, abdominal pain, nausea, vomiting or significant anemia.
  • Severe-fulminant disease: Those with symptoms despite taking corticosteroid treatment (see below), or individuals with high fevers, persistent vomiting, evidence of obstructed intestines, severe weight loss or major infection.
  • Remission: no symptoms are present

What Triggers a Worsening of Crohn's Disease?

Crohn's disease is characterized by periods of being symptomatic, which can last for days or weeks, interspersed with periods of remission (no symptoms are present). Remissions can last days, weeks or even years.

Factors that worsen Crohn's disease include:


Inflammatory Bowel Disease (IBD) Causes, Symptoms, Treatment See Slideshow

How Is Crohn's Disease Treated?

Though treatments cannot cure Crohn's disease, they can help most people lead normal lives.


Crohn's disease is treated primarily with medications, including:

  • Anti-inflammatory drugs, such as salicylates. Examples include Azulfidine (sulfasalizine), Dipentum, and Pentasa. Side effects include gastrointestinal upset, headache, nausea, diarrhea, or rash.
  • Corticosteroids, a more powerful type of anti-inflammatory drugs. Examples include prednisone or Solu-Medrol, and Entocort. Side effects, if taken for long periods of time, can be severe and may include bone thinning, muscle loss, skin problems, increased risk of infection. Entocort has fewer side effects.
  • Immune system modifiers such as azathioprine (Imuran) or methotrexate. It can take up to six months for these drugs to work. These medications are associated with increased risk for infections that can be life-threatening.
  • Antibiotics such as Flagyl, Cipro and others. Flagyl can cause a metallic taste in the mouth, nausea and tingling or numbness of the hands and feet. Cipro can cause nausea and has been associated with rupture of the Achilles tendon.
  • Antidiarrheal drugs
  • Biologic therapy, such as Remicade. Remicade neutralizes the activity of a substance called tumor necrosis factor alpha (TNF-alpha). This substance is overproduced by people with Crohn's and plays an important role in causing the inflammation associated with Crohn's disease. The drug is given intravenously (through the vein). Side effects include life-threatening infection, infusion reaction, headache, stomach upset, fatigue, fever, pain, dizziness, rash, and itching.

Response to therapy is evaluated within several weeks of starting treatment. Treatment is continued until remission is obtained (at which time, the health care provider may consider maintenance therapy). No improvement calls for more aggressive therapy. Nutritional supplements may also be recommended by your doctor.


Surgery is required in about one-half of people with Crohn's disease to treat complications of the disease, such as, fistulas, abscesses, hemorrhage, and intestinal obstructions. Surgery may also be necessary in people who do not respond to medications.

In most cases, the diseased part of the bowel is removed and the two healthy ends of bowel are joined together (anastomosis). This surgery can allow many people to remain symptom-free for years, but it is not a cure since Crohn's disease often recurs at the site of the anastomosis.

Unfortunately, too many resection surgeries can lead to a condition called short gut syndrome where there isnt enough bowel left to adequately absorb nutrients.

Other surgeries include repair of parts of the intestine that have narrowed (a stricture) or abscessed (infection).

An ileostomy may also be required if the rectum is diseased and cannot be utilized for an anastomosis. This is a connection of the intestine to the skin overlying the abdominal wall. The result is an opening in the skin from which waste products can be excreted into a specially designed pouch.

Treatment By Activity or Location of Disease

Mild-moderate disease (of the ileum or colon):

  • Oral Pentasa (mesalamine) or Azulfidine (sulfasalizine)
  • If you dont respond to those treatments, antibiotic therapy with Flagyl or Cipro is also an option
  • Steroid treatment may be started if there is no response to the above medications.

Moderate-severe disease:

  • Steroid treatment until symptoms resolve and weight gain is sustained (7-28 days).
  • Infection is treated with appropriate antibiotics unless it's an abscess where its treated with drainage.
  • Therapy with Imuran, methotrexate, or Remicade is an alternative for people who do not respond to standard therapy.

Severe-fulminant disease:

People with persistent symptoms despite taking Remicade or steroids or those with symptoms of serious illness should be hospitalized. Treatment includes:

  • Surgery for any abscesses, obstruction or fistulae.
  • Intravenous (by vein) corticosteroids for those who were on oral steroids.
  • Nutritional support using TPN after 5-7 days if the person is unable to maintain nutritional requirements with oral nutrition. Transfusions for severe anemia or blood loss.
  • Antibiotics for treatment of infection.

Perianal disease:

  • Abscesses in the anal or rectal area (perianal or perirectal abscess) require surgical drainage.
  • Fistulas in this area that can also be treated with antibiotics.

Maintenance therapy to prevent relapse:

  • Imuran/mercaptopurine combination after initial treatment with steroids.
  • Pentasa or Imuran/mercaptopurine combination can be given after resection of parts of the intestine to reduce recurrence of disease.

What Role Does Diet Play in Crohn's Disease?

While foods appear to play no role in causing the disease, soft, bland foods may cause less discomfort than spicy or high-fiber foods when the disease is active. Except for restricting milk in lactose intolerant people, most gastroenterologists try to be flexible in planning the diets of their Crohn's disease patients. Ask your doctor to create a dietary plan for you.

Reviewed by The Cleveland Clinic Department of Gastroenterology.
Edited by Louise Chang, MD, WebMD, November 2005.

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