Crohn's Disease

Reviewed on 7/23/2022

Things to Know About Crohn's Disease

Detailed picture showing the areas affected by Chron's disease.
Detailed picture showing the areas affected by Crohn's disease.
  • Crohn's disease definition: a chronic inflammatory condition of the gastrointestinal tract (GI tract) that can occur anywhere in the tract.
  • A person should seek medical diagnosis first and then seek treatment when experiencing symptoms (for example, diarrhea that is intermittent, abdominal pain and/or bloating after eating, constipation, pain and/or blood with bowel movements and fistula formations).
  • Treatment involves reducing inflammation in Crohn's disease that may include anti-inflammatory drugs, corticosteroids, other immunosuppressants, biologics, and antibiotics along with a diet that reduces the risk of inflammation from certain foods (Crohn's disease diet). Surgery may be needed in some patients to remove a section of the GI tract.
  • Crohn's disease is a chronic inflammatory condition of the GI (gastrointestinal tract) and can appear anywhere in the GI tract.
  • Crohn's disease sometimes is called regional enteritis or ileitis. It and a similar condition called ulcerative colitis are referred to together as inflammatory bowel disease (IBD). These illnesses are known for their unpredictable flares and remissions.
  • The inflammation usually starts in one or more areas of the mucosa that lines the inside of the intestines.
  • The disease may invade deeper tissues of the intestinal wall and spread to involve more areas of the bowel.
  • Ulcers may form at the sites of the most intense inflammation.
  • The ulcers may spread and become very large but are usually separated by areas of relatively healthy tissue with little or no inflammation.
  • The mucosal lining of the intestines in Crohn's disease is often described as looking like a cobblestone street, with areas of ulceration separated by narrow areas of healthy tissue.
  • The damage to the intestinal wall caused by the inflammation results in a wide variety of symptoms and complications.
  • The inflammation damages the lining of the intestine so that it cannot absorb nutrients, water, and fats from the food you eat. This is called malabsorption, and it can result in malnutrition, dehydration, vitamin and mineral deficiencies, gallstones, and kidney stones.
  • As the inflammation invades deeper into the intestinal tissues, the intestinal wall becomes thicker, narrowing the bowel lumen (the space through which food passes). The intestinal lumen may become so narrow that it becomes obstructed, so that food cannot pass through at all. This obstruction is usually intermittent, meaning that it comes and goes, and gets better with medical treatment. Eventually, however, the obstruction can become permanent as the scar tissue develops.
  • If the inflammation in one area spreads all the way through the intestinal wall, the inflamed area can stick to other organs and structures in the abdomen. This leads to the formation of fistulas (abnormal connections) between the bowel and other organs and structures in the abdomen.
  • Crohn's disease can also cause problems around the anus. These may include tiny but painful cracks in the skin known as anal fissures. Tunneling sores called fistulas cause abnormal connections between the bowel and the skin; or an abscess, a pocket of inflamed or dead tissue that is usually very painful.
  • Sometimes fistulas can develop between the intestine and/or other organs and structures it is not normally connected to, such as between different parts of the bowel, the bladder, the vagina, or even the skin on the outside of the body. This is serious because the contents of the intestine can enter into these other sites, causing infection and other problems.
  • Crohn's disease can cause a variety of related inflammatory conditions outside of the digestive tract. The usual sites are skin, joints, mouth, eyes, liver, and bile ducts.
  • Children with Crohn's disease may experience delayed development and stunted growth.
  • Inflammatory bowel disease (Crohn's disease and ulcerative colitis) is one of the five most prevalent GI diseases in the United States. IBD is a chronic medical condition that requires a lifetime of care. IBD is responsible for the disability of approximately 119,000 individuals in the United States.
  • Crohn's disease is more prevalent in whites than in African Americans and Asians.
  • In the United States, Europe, and South Africa, Crohn's disease is 2 to 4 times more common among people of Jewish descent than among other ethnic or social groups.
  • Crohn's disease is slightly more common among men than women.
  • In general, the prevalence is higher in urban areas than in rural areas. It is also higher in higher socioeconomic classes.
  • Crohn's disease can occur at any age, but most people newly diagnosed with Crohn's disease are aged 15 to 30 years. It is sometimes newly diagnosed in people aged 60 to 80 years.
  • Crohn's disease can be a debilitating illness. However, with medical treatment and other measures used to reduce the discomfort of flares, most people learn to cope with the condition. Almost everyone with Crohn's disease can live a normal life.

What Is Crohn's Disease?

Crohn's disease (also called Crohn disease) is a chronic (slowly developing, long-term) inflammation of the digestive tract. It can affect any part of the digestive tract from the mouth to the anus but usually involves the terminal part of the small intestine, the beginning of the large intestine (cecum), and the area around the anus. The inflammation causes uncomfortable and bothersome symptoms and may produce serious damage to the digestive tract.

What Are the First Signs and Symptoms of Crohn's Disease?

Crohn's disease is intermittent. This means that the inflammation occurs (flares) without warning and then goes away (goes into remission) over time. It is impossible to predict when the condition will flare, how long the flare will last, and when it will flare again. Most people feel pretty well when their disease is not active.

The most common symptoms in Crohn's disease are those related to the inflammatory damage to the digestive tract. Crohn's disease symptoms include:

  1. Diarrhea: Waxes and wanes; stool may contain mucus, blood, or pus
  2. Pain in the abdomen: Crampy or steady; in the right lower part of the abdomen or around the belly button; often relieved temporarily by having a bowel movement
  3. Bloating after eating: Less common, usually seen in cases of bowel obstruction
  4. Constipation Usually seen in cases of bowel obstruction
  5. Pain or bleeding with bowel movement
  6. Infection of the urinary tract or vagina: Suggests a fistula from the intestinal tract

General symptoms occur in some but not all cases, such as:

  1. Low-grade fevers
  2. Weight loss
  3. Fatigue

Other symptoms of Crohn's disease may be attributable to related medical conditions affecting the

  • skin, 
  • joints,
  • mouth,
  • eyes, (uveitis or Crohn's disease eyes),
  • liver, and
  • bile ducts.

What Causes Crohn's Disease?

The exact cause of Crohn's disease remains unknown.

  • Current theories suggest that genetics, environment, diet, blood vessel abnormalities, and/or even psychosocial factors could be among the Crohn's disease causes.
  • Probably the most popular theory is that Crohn's disease is caused by the immune system overreacting to infection by a virus or bacterium.
  • Crohn's disease apparently is not caused by emotional distress.
  • Crohn's disease definitely runs in families, so the disease likely has a hereditary component. People who have Crohn's disease may have an inherited predisposition to abnormal immunologic response to one or more provoking factors.

How Do Doctors Diagnose Crohn's Disease?

Crohn's disease can be difficult to diagnose because the symptoms are nonspecific, meaning that they occur with many different gastrointestinal disorders. There is no single Crohn's disease test. Your health care professional conducts a detailed medical interview to try to pinpoint the diagnosis. Patients will be asked questions about their symptoms, medical problems they have had in the past, previous surgeries, medications they are currently taking, family history, diet, habits, and lifestyle. Patients will be examined carefully for physical signs that might reveal the diagnosis.

Blood tests may be ordered to test for Crohn's disease. The purpose of these is to detect inflammation or nutritional deficiencies.

  • Blood cell counts: Complete blood count (CBC) blood test may show abnormalities and may indicate anemia or inflammation.
  • Electrolytes: Low levels may be an indication of problems in absorbing nutrients from foods in the intestine.
  • Protein (albumin): Again, a low level may indicate absorption problems in the digestive tract.
  • C-reactive protein and orosomucoid: These are markers of inflammation, and their levels correlate with how active the disease is.
  • Erythrocyte sedimentation rate: This is another marker of inflammation and disease activity.
  • Perinuclear antineutrophil cytoplasmic antibody (p-ANCA) antigen and anti-S cerevisiae antibodies (ASCA): These tests are useful in distinguishing Crohn's disease from ulcerative colitis. A test result positive for p-ANCA antigen and negative for ASCA suggests the diagnosis of ulcerative colitis; a test result positive for ASCA and negative for p-ANCA antigen suggests Crohn's disease.

A stool sample may be collected to check for blood and signs of inflammation or infection, including parasites that could cause similar symptoms.

A person may undergo imaging studies (X-ray films) to detect the extent of Crohn's disease and any complications that may have developed.

  • Barium contrast studies is a series of X-ray films taken after you drink a contrast material containing a chalky substance called barium. The barium allows the intestine to show up better than on a plain X-ray film. Barium studies are very useful in defining the nature, distribution, and severity of the disease. The barium studies may include an upper GI series or barium swallow (X-ray films of the upper part of the digestive system) and a small bowel follow-through (X-ray films of the small intestine).
  • Barium enema works on the same principal as the barium contrast studies of the upper digestive system, but the barium is introduced into the lower digestive tract through the rectum. This test is done to see whether the patient's colon and rectum are involved, and to what extent.
  • CT scan called CT enterography or MRI called MR enterography is useful for assessing the extent of involvement of small intestine in Crohn's.
  • Ultrasound is helpful in assessing complications outside of the intestine, such as fistulas, an abscess, or abnormalities of the liver, bile duct, or kidneys. MRI may be used instead.

Endoscopy is used to examine the lining of the stomach, upper intestine, or colon; and often provides the best information about the extent of involvement due to Crohn's.

  • Endoscopy involves inserting a thin tube with a light and a tiny camera on the end into a body cavity or organ. The camera transmits pictures of the inside of the organ so that the doctor can see inflammation or bleeding or other signs of problems.
  • Both the upper and the lower parts of the digestive tract can be examined endoscopically. Endoscopy of the lower part of the digestive tract is called colonoscopy. Endoscopy of the upper digestive tract is usually called simply upper endoscopy (EGD, esophagogastroduodenoscopy).
  • In both cases, the doctor can use the endoscope to take a biopsy. A biopsy is a tiny sample of tissue taken from the mucosal lining of the digestive tract. These tissues are examined under a microscope by a pathologist (a doctor who specializes in diagnosing diseases by examining tissues and cells in this way).
  • Endoscopic retrograde cholangiopancreatography (ERCP) is another endoscopic procedure that is helpful for both diagnosis and treatment in people who have Crohn's disease in their pancreas or bile duct, called sclerosing cholangitis.

What Is the Treatment for Crohn's Disease and Its Symptoms?

The goals of Crohn's disease treatment are to reduce the underlying inflammation, which then relieves symptoms, prevents complications, and maintains good nutrition.

  • Medications used in reducing inflammation in Crohn's disease include anti-inflammatory drugs, corticosteroids, other immunosuppressants, biologics, and antibiotics. The types of medications most widely used in Crohn's disease are the following:
  • Aspirin-like anti-inflammatory drugs, for example, mesalamine (Apriso, Asacol, Asacol HD, Lialda, Pentasa) -- reduce inflammation. These drugs are used to prevent flares in people with mild Crohn's disease.
  • Corticosteroids reduce inflammation and suppress the immune system. They can be used in the short term only. Corticosteroids are indicated in persons with severe systemic symptoms (for example, fever, nausea, weight loss) and in those who do not respond to anti-inflammatory agents.
  • Antibiotics reduce inflammation indirectly by reducing infection.
  • Immunosuppressants suppress the immune system. Some are more effective than steroids, while others have a longer duration of effect.
  • Biologic therapy works as an anti-TNF blocker, which also helps in reducing inflammation.

If these drugs are not successful in suppressing inflammation, the alternative is surgery to manage the complications of Crohn's disease.

Symptoms often go away when the inflammation is treated. Symptoms may be treated separately if necessary.

  • For symptoms such as diarrhea, cramps, and bloating, medication is usually enough. Antidiarrheal agents usually relieve mild to moderately severe symptoms.
  • Diet changes, such as diets high in fiber, low in fiber, or low in fat, are helpful in some people over the short term but are rarely helpful over the long term.
  • Do not take dietary supplements or vitamins without first discussing them with a health care professional.
  • Many people with Crohn's disease are lactose intolerant and should avoid dairy products if they are intolerant to them.

Most complications resolve when the inflammation is treated. Some, however, require additional treatment. A fistula, for example, usually is treated with antibiotics to get rid of the infection. The doctor may prescribe other medications to help heal the fistula, but these work in only about 30%-40% of cases.

  • During this treatment, the patient may have to stop eating and receive nutritious fluids intravenously for several days. A nasogastric (NG) tube placed in the stomach through the nose will remove some of the fluids and gases that collect there. This combination of approaches, called bowel rest, lets the digestive tract stop working temporarily, which promotes healing.
  • Fistulas that bypass a large amount of the intestine (thus causing very severe symptoms) or do not improve with medical treatment may need to be repaired surgically.

What Other Medications and Therapies Treat Crohn's Disease?

Often these medications are used together in various combinations, although they are also used alone. Like all drugs, these may have side effects that may require changing the dose or stopping the drug altogether.

Aspirin-like anti-inflammatory drugs

  • Mesalamine (Asacol HD, Rowasa, Lialda, Apriso, Giazo, Canasa) tends to work best in Crohn's disease affecting mainly the colon and to some extent the end of the small intestine. Oral and rectal suppository forms are available. Long-term use may delay relapse of the disease.
  • Sulfasalazine (Azulfidine) tends to work best in Crohn's disease affecting mainly the colon. It does not work in the small intestine. Long-term use generally does not delay relapse. People on sulfasalazine should take folic acid.



Corticosteroids probably work the best of any drugs used to treat Crohn's disease because they exert both anti-inflammatory and immunosuppressant effects. They can only be taken for short periods because of the many potentially severe side effects.

Immunosuppressants and biologic therapy

Immunosuppressants interfere with the development of immunological responses. They are an alternative treatment for people whose Crohn's disease has relapsed after steroid therapy.

Biologic therapy works against tumor necrosis factor and are called anti-TNF agents.

  • Infliximab (Remicade) is a monoclonal antibody that acts against tumor necrosis factor alpha, a natural product of the immune system that promotes inflammation. Infliximab is used to treat moderately severe-to-severe Crohn's disease that does not get better with other medications. When given as an intravenous infusion, its effects last for approximately 12 weeks. Repeated doses may be required.
  • Other anti-TNF agents available and approved in Crohn's include: adalimumab (Humira) given as a subcutaneous injection twice a month , and certolizumab (Cimzia) given as an injection once a month.

Newer immunosuppressant agents, such as tacrolimus (Prograf) and mycophenolate mofetil (CellCept), and natural products of the immune system that fight inflammation, such as specific interleukins, are being tested in Crohn's disease.

Are There New Crohn's Disease Medications?

Newer immunosuppressant agents, such as tacrolimus (Prograf) and mycophenolate mofetil (CellCept), and natural products of the immune system that fight inflammation, such as specific interleukins, are being tested in Crohn's disease.

When Is Surgery Necessary to Remove Part of the Colon in Crohn's Disease?

  • The most widely used operation in Crohn's disease is removing the diseased part of the intestine.
  • Surgery is usually necessary in people who have intestinal obstruction or very severe symptoms that are not relieved by medication. It can improve the condition, but it does not cure it.
  • Surgery also may be necessary for an abscess or certain types of fistulas.
  • People who have part of their bowel removed may require an ostomy.
  • The normal bowel is attached to an opening in the lower abdomen called a stoma. Feces are no longer passed from the body through the rectum and anus, but through this stoma. An ostomy bag is worn on the outside of the body to collect the waste. The ostomy often is called by which part of the bowel is attached, such as colostomy or ileostomy.
  • Crohn's disease recurs frequently after surgery. If a part of the bowel is removed, the recurrence often occurs at the place where the diseased bowel was cut in the operation. Hence careful follow-up after surgery is important, even when the patient feels well, to detect early signs of recurrence. Patients may have to continue treatment even after surgery to help in reducing the rate of recurrence of Crohn's disease.
  • People who have part of their small intestine removed may experience a complication known as short bowel syndrome. Ironically, the symptoms of short bowel syndrome often are similar to those of Crohn's disease. This complication is now uncommon with modern surgery.
  • Patients who have had large portions of their intestine removed often need to rely on intravenous nutrition (total parenteral nutrition, or TPN) for the rest of their lives.

What Is the Progression of Crohn's Disease, Is It Fatal?

Patients will need to visit their health care professional regularly so that their medical condition can be monitored, and so the doctor can determine how well treatment is working, and check for relapse and return of symptoms.

The intestinal complications of Crohn's disease include:

  • Intestinal obstruction
  • Fistulas
  • Abscess
  • Hemorrhage (bleeding) - Unusual in Crohn's disease
  • Malabsorption - Results in diarrhea and nutritional deficiencies
  • Acute regional enteritis
  • Carcinoma - Colonic disease increases the risk of colon cancer

Although Crohn's disease is a chronic illness with episodes of remission and relapses, appropriate medical and surgical therapies help affected individuals have a reasonable quality of life.

  • Crohn's disease usually has a chronic, slow course regardless of the site of involvement.
  • Medical therapy becomes less effective with time.
  • Nearly two-thirds of people with Crohn's disease require surgery for complications at some point in their disease.
  • The longer a person has Crohn's disease, the more likely the individual is to develop complications that can be fatal.
  • Cancer of the digestive tract is the leading cause of death for people with Crohn's disease.
  • Crohn's disease frequently recurs after surgery.

What Support Groups and Counseling Are Available for People with Crohn's Disease?

Living with the effects of Crohn's disease can be difficult. Sometimes you will feel frustrated, perhaps even angry or resentful. Sometimes it helps to have someone to talk to.

This is the purpose of Crohn's disease support groups. Support groups consist of people in the same situation you are in. They come together to help each other and to help themselves. Support groups provide reassurance, motivation, and inspiration. They help you see that your situation is not unique, and that gives you power. They also provide practical tips on coping with this disorder.

Support groups meet in person, on the telephone, or on the Internet. To find a support group that works for you, ask your health care professional, contact the following organization or look on the Internet. If you do not have access to the Internet, go to the public library.

  • Crohn's & Colitis Foundation - (800) 932-2423

Health Solutions From Our Sponsors

Crohn's Disease Diet

Several factors contribute to nutritional problems in people with Crohn's disease. Malabsorption and intestinal inflammation decreases nutritional intake, which results in Crohn's disease flares and complications. While there is no specific diet for Crohn's disease, certain foods may trigger flares, for example:

  • Dairy products
  • Spicy foods
  • Fatty or fried foods
  • High-fiber foods (vegetables, nuts, seeds, and popcorn)
Reviewed on 7/23/2022
Regueiro, M., et al. "Overview of the medical management of mild (low risk) to moderate Crohn's disease in adults." UpToDate. Nov 25, 2019. <>.

United States. CDC. "What Is Inflammatory Bowel Disease (IBD)?" Apr. 13, 2022. <>.