Crohn’s Disease


What Is It?

Crohn’s disease is a long-term (chronic) condition in which inflammation causes injury to the intestines. It typically begins in young adulthood, most often between ages 15 and 40.

No one knows for sure what triggers intestinal inflammation. Many experts think that a virus or a bacterial infection might start the process, and that the body’s immune system malfunctions and stays active even after the infection goes away. Family members may share genes that make Crohn’s disease more likely to develop if the right trigger occurs. Ten percent to 25 percent of people who have Crohn’s disease have at least one relative with Crohn’s disease or a similar disease called ulcerative colitis.

Once Crohn’s disease begins, it can cause lifelong symptoms that come and go. The inside lining and deeper layers of the intestine wall become inflamed. The lining of the intestine becomes irritated, and can thicken or wear away in spots. This creates ulcers, cracks and fissures. Inflammation can allow an abscess (a pocket of pus) to develop.

Between attacks of inflammation, the intestine attempts to heal by recoating itself with a new lining. When the inflammation has been severe, the intestine can lose its ability to distinguish the inside of one piece of intestine from the outside of another piece. As a result, it can mistakenly build a lining along the edges of an ulcer that has worn through the whole wall of the intestine. This creates a fistula, an abnormal connection between one piece of the intestine and another. A fistula sometimes can form between the intestine and the skin surface, creating a connection to the skin.

The section of the small intestine called the ileum (in the right lower abdomen) is especially prone to damage from Crohn’s disease. However, ulcers and inflammation can occur in all areas of the digestive tract, from the mouth all the way to the rectum. A few other parts of the body, such as the eyes and joints, also can be affected in people with Crohn’s disease.


Some people with Crohn’s disease have only occasional cramps, or diarrhea that is so mild they do not seek medical attention. However, most people who have Crohn’s disease experience long stretches of time with no symptoms interrupted by bursts of symptoms, called an exacerbation, when inflammation returns. During an exacerbation, or during the initial appearance of Crohn’s disease, you might experience the following symptoms:

  • Abdominal pain, usually at or below the navel, typically worse after meals
  • Diarrhea that may contain blood
  • Sores around the anus, or drainage of pus or mucus from the anus or anal area
  • Pain when you have a bowel movement
  • Mouth sores
  • Loss of appetite
  • Joint pains or back pain
  • Pain or vision changes in one or both eyes
  • Weight loss despite eating a normal-calorie diet
  • Fever
  • Weakness or fatigue
  • Stunted growth and delayed puberty in children


It may require months for your doctor to diagnose Crohn’s disease with certainty. Your doctor will look for evidence of intestinal inflammation and try to distinguish it from other causes of intestinal problems, such as infection or ulcerative colitis, a related disease that also causes intestinal inflammation. If you have Crohn’s disease, your symptoms and the results of various tests will fit a pattern over time that is best explained by this condition.

Tests that can indicate inflammation and show evidence of Crohn’s disease include:

  • Blood tests showing a high white blood cell count or other signs of inflammation in your body
  • A blood test for anemia, which is a reduced number of red blood cells
  • Autoantibody tests that reveal antibodies in the blood of people with Crohn’s disease, although it is not clear how helpful these tests are in establishing the diagnosis
  • Stool (also called feces or bowel movement) tests that show bleeding from irritated intestines, and that do not show signs of infection
  • An X-ray test called an upper GI (gastrointestinal) series, in which pictures are taken of your abdomen after you drink a white, chalky barium solution that shows up on X-rays. As the liquid trickles down, it traces the outline of your intestines on the X-ray. An upper GI series can reveal places in the intestine that are narrowed because the intestine wall is thickened. It also can highlight ulcers and show detours in the intestine, which may be a fistula.
  • Flexible sigmoidoscopy or colonoscopy tests, which use a small tube inserted into the rectum that contains a camera and light that allow your doctor to view the insides of your large intestine
  • biopsy is the removal of a small sample of tissue from the lining of the intestine. The material is examined under a microscope for signs of inflammation. A biopsy is most helpful to confirm Crohn’s disease and to exclude other conditions.

Expected Duration

Crohn’s disease is a lifelong condition, but it is not continuously active. There can be long periods during which you have no symptoms. Following a flare-up, however, symptoms can stay with you for weeks or months. Often these flare-ups are separated by months or years of good health without any symptoms.


There is no way to prevent Crohn’s disease, but you can keep the condition from taking a heavy toll on your body by maintaining a well-balanced, nutritious diet. By storing up vitamins and nutrients between episodes or flare-ups, you can decrease complications from poor nutrition, such as weight loss or anemia. Your doctor will monitor your blood for complications of poor nutrient absorption.

Crohn’s disease can cause a higher risk of colon cancer, particularly if it affects a large portion of the colon or rectum. It is important to have your colon checked regularly for early signs of cancer or for changes that can precede a new cancer. If you have had Crohn’s disease affecting the colon or rectum for eight years or more, it is time for you to start getting regular testing to look for cancer. One good strategy is to have a colonoscopy exam every one to two years once you start regular testing.


Medications are very effective at improving the symptoms of Crohn’s disease. Most of the drugs work by preventing inflammation in the intestines.

The medication commonly used first is a group of anti-inflammatory drugs called aminosalicylates. Related chemically to aspirin, they suppress inflammation in the intestine and in joints. They are given either by mouth (pills) or by rectum, as an enema. Some drugs in this group include sulfasalazine (Azulfidine), mesalamine (Asacol, Pentasa, Canasa, Rowasa) and olsalazine (Dipentum).

Certain antibiotic drugs, particularly metronidazole (Flagyl) and ciprofloxacin (Cipro), help by decreasing the bacterial growth in irritated areas of the bowel. They may have a side benefit of decreasing inflammation, too. If you still have diarrhea, but there is no infection, antidiarrheal medications, such as loperamide (Lomotil) may be helpful.

Other more powerful anti-inflammatory drugs may be helpful, but they can also suppress your immune system so that you have an increased risk of infections. For this reason, they are not often used on a long-term basis. These drugs include prednisone (Deltasone, Prednisolone, Orasone) and methylprednisolone (Medrol, Solu-Medrol), budesonide (Entocort), azathioprine (Imuran), 6-mercaptopurine (Purinethol), cyclosporine (Neoral, Sandimmune) and methotrexate (Rheumatrex, Folex).

A new drug, infliximab (Remicade) has been used in recent years for severe Crohn’s disease, particularly when a fistula has formed that does not respond to other treatment. This medication blocks the effect of a chemical (tumor necrosis factor) that may be responsible for causing inflammation in the intestine.

Surgery is another possible treatment. In general, surgery to remove a section of the bowel is recommended only if a person has bowel obstruction, persistent symptoms despite medical therapy, or a non-healing fistula. Up to 50 percent of people who have Crohn’s disease will end up having at least one operation during the course of their disease.

When To Call A Professional

New or changing symptoms often mean that additional treatment is needed to keep Crohn’s disease under control. For this reason, people who have Crohn’s disease should be in frequent contact with a doctor. One serious complication, bowel obstruction, causes vomiting or severe abdominal pain and requires emergency treatment. This occurs when the inside of the intestine becomes narrowed, so that the digestive contents cannot pass through. Other symptoms that require a doctor’s immediate attention are fever (which could indicate infection), heavy bleeding from the rectum, or black paste-like stools (indicative of how blood looks after traveling a long distance through the intestine).


Crohn’s disease can affect people very differently. Many people have only mild symptoms and do not require continuous treatment with medication. Others require multiple medications and develop complications. Crohn’s disease improves with treatment and is not a fatal illness, but it cannot be cured. Crohn’s requires people to pay special attention to their health needs and to seek frequent medical care, but it does not prevent most people from having normal jobs and productive family lives. As is the case for any chronic illness, it can be helpful for a newly diagnosed person to seek advice from a support group of other people with the disease.

For more information see:
Crohn’s Disease
Crohn’s Disease
Crohn’s Disease

Johns Hopkins patient information

Last revised:

Diseases and Conditions Center

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.