Although the exact cause is unknown, an improperly triggered immune system may result in Crohn disease.
Typical symptoms include chronic diarrhea (which sometimes is bloody), crampy abdominal pain, fever, loss of appetite, and weight loss.
The diagnosis is based on a colonoscopy, video capsule endoscopy, and imaging tests such as barium x-rays, computed tomography, or magnetic resonance imaging.
There is no cure for Crohn disease.
Treatment is aimed at relieving symptoms and reducing inflammation, and some people require surgery.
(See also Overview of Inflammatory Bowel Disease (IBD) Overview of Inflammatory Bowel Disease (IBD) In inflammatory bowel diseases, the intestine (bowel) becomes inflamed, often causing recurring abdominal pain and diarrhea. The two primary types of inflammatory bowel disease (IBD) are Crohn... read more .)
In the past few decades, Crohn disease has become more common worldwide. However, it is most common among people of Northern European and Anglo-Saxon descent. It occurs about equally in both sexes, often runs in families, and seems to be more common among Ashkenazi Jews. Most people develop Crohn disease before age 30, usually between the ages of 14 and 24. A few people have their first attack between the ages of 50 and 70.
Most commonly, Crohn disease occurs in the last portion of the small intestine (ileum) and in the large intestine, but it can occur in any part of the digestive tract, from the mouth to the anus and even in the skin around the anus. Inflammation of the ileum is called ileitis. When Crohn disease affects the colon, it is called Crohn colitis. Crohn disease affects
The small intestine alone (35% of people)
The large intestine alone (20% of people)
Both the last portion of the small intestine and the large intestine (45% of people)
The rectum is usually not affected, unlike in ulcerative colitis Ulcerative Colitis Ulcerative colitis is a chronic inflammatory bowel disease in which the large intestine (colon) becomes inflamed and ulcerated (pitted or eroded), leading to flare-ups (bouts or attacks) of... read more , in which the rectum is always involved. However, infections and other complications around the anus are not unusual. The disease may affect some segments of the intestinal tract while leaving normal segments (called skip areas) between the affected areas. Where Crohn disease is active, the full thickness of the bowel is usually involved.
Locating the Small and Large Intestines
The cause of Crohn disease is not known for certain, but many researchers believe that a dysfunction of the immune system causes the intestine to overreact to an environmental, dietary, or infectious agent. Certain people may have a hereditary predisposition to this immune system dysfunction. Cigarette smoking seems to contribute to both the development and the periodic flare-ups (bouts or attacks) of Crohn disease. Oral contraceptives may increase the risk of Crohn disease.
For unclear reasons, people who have a higher socioeconomic status may have an increased risk of Crohn disease.
Several reports suggest that people who were breastfed may be protected from developing inflammatory bowel disease.
Symptoms of Crohn Disease
The most common symptoms of Crohn disease are
Crampy abdominal pain
Chronic diarrhea (which sometimes is bloody when the large intestine is severely affected)
Loss of appetite
Symptoms of Crohn disease may continue for days or weeks and may resolve without treatment. Complete and permanent recovery after a single attack is extremely rare. Crohn disease almost always flares up at irregular intervals throughout a person's life. Flare-ups can be mild or severe, brief or prolonged. Severe flare-ups can lead to intense, constant pain, fever, and dehydration.
Why the symptoms come and go and what triggers new flare-ups or determines their severity is not known. Recurring inflammation tends to appear in the same area of the intestine. It also may appear in areas near where a diseased segment has been removed surgically.
In children, abdominal pain and diarrhea often are not the main symptoms and may not appear at all. Instead, the main symptoms may be slow growth, joint inflammation (arthritis), fever, or weakness and fatigue resulting from anemia.
Complications of Crohn disease
Complications of Crohn disease include
Fistulas Anorectal Fistula An anorectal fistula is an abnormal channel that leads from the anus or rectum usually to the skin near the anus but occasionally to another organ, such as the vagina. Anorectal fistulas are... read more (abnormal connecting channels between the intestine and skin or other organs)
Toxic megacolon is a rare complication that can happen when Crohn disease affects the large intestine (colon). The large intestine stops its normal contractions and dilates, sometimes leading to peritonitis Peritonitis Abdominal pain is common and often minor. Severe abdominal pain that comes on quickly, however, almost always indicates a significant problem. The pain may be the only sign of the need for surgery... read more . People may need surgery.
Scarring due to chronic inflammation can cause intestinal blockage. Deep ulcers that penetrate through the bowel wall can create abscesses, open fistulas, or perforations. Fistulas may connect two different parts of the intestine. Fistulas may also connect the intestine and bladder or the intestine and the skin surface, especially around the anus. Although fistulas from the small intestine are common, wide-open holes (perforations) are rare. Fissures in the skin of the anus are common.
When the large intestine is affected extensively by Crohn disease, rectal bleeding commonly occurs. After many years, the risk of colon cancer (cancer of the large intestine) is increased in people who have Crohn colitis. About one third of people who develop Crohn disease have problems around the anus, especially fistulas and fissures in the lining of the mucus membrane of the anus.
Crohn disease may lead to complications in other parts of the body. These complications include
When Crohn disease causes a flare-up of gastrointestinal symptoms, the person may also have the following:
Inflammation of the joints (arthritis)
Even when Crohn disease is not causing a flare-up of gastrointestinal symptoms, the person still may have the following entirely without relation to the bowel disease:
Inflammation of the pelvic joints (sacroiliitis)
Diagnosis of Crohn Disease
Blood and stool tests
A doctor may suspect Crohn disease in a person with recurring crampy abdominal pain and diarrhea, particularly if the person has a family history of Crohn disease or a history of problems around the anus. Other clues to the diagnosis may include inflammation in the joints, eyes, or skin or stunted growth in a child. The doctor may feel a lump or fullness in the lower part of the abdomen, most often on the right side.
Blood and stool tests
No laboratory test specifically identifies Crohn disease, but blood tests may show anemia, abnormally high numbers of white blood cells, low levels of the protein albumin, and other indications of inflammation, such as an elevated erythrocyte sedimentation rate or level of C-reactive protein. A doctor may also do liver tests.
If diarrhea is present, a doctor may collect stool samples to rule out certain intestinal infections Causes Gastroenteritis is inflammation of the lining of the stomach and small and large intestines. It is usually caused by infection with a microorganism but can also be caused by ingestion of chemical... read more .
People who have severe abdominal pain and tenderness often have a computed tomography Computed Tomography and Magnetic Resonance Imaging of the Digestive Tract Computed tomography (CT— see also Computed Tomography (CT)) and magnetic resonance imaging (MRI— see also Magnetic Resonance Imaging (MRI)) scans are good tools for assessing the size and location... read more (CT) scan or magnetic resonance imaging Computed Tomography and Magnetic Resonance Imaging of the Digestive Tract Computed tomography (CT— see also Computed Tomography (CT)) and magnetic resonance imaging (MRI— see also Magnetic Resonance Imaging (MRI)) scans are good tools for assessing the size and location... read more (MRI) of their abdomen. CT or MRI may show a blockage, abscesses or fistulas, and other possible causes of inflammation of the abdomen (such as appendicitis Appendicitis Appendicitis is inflammation and infection of the appendix. Often a blockage inside the appendix causes the appendix to become inflamed and infected. Abdominal pain, nausea, and fever are common... read more ).
People who have had symptoms that recur over a period of time may have x-rays taken of the stomach and small intestine after drinking liquid barium (called an upper gastrointestinal [GI] series) or have x-rays taken after receiving barium as an enema (called a barium enema X-Ray Studies of the Digestive Tract X-rays often are used to evaluate digestive problems. Standard x-rays (plain x-rays) do not require any special preparation ( see Plain X-Rays). These x-rays usually can show a blockage or paralysis... read more ). Newer approaches include CT enterography CT enterography and MR enterography Computed tomography (CT— see also Computed Tomography (CT)) and magnetic resonance imaging (MRI— see also Magnetic Resonance Imaging (MRI)) scans are good tools for assessing the size and location... read more or magnetic resonance enterography. Another way in which the small intestine can be evaluated is with video capsule endoscopy Video Capsule Endoscopy Video capsule endoscopy (wireless video endoscopy) is a procedure in which the person swallows a battery-powered capsule. The capsule contains one or two small cameras, a light, and a transmitter... read more .
People who have little pain and mostly diarrhea undergo a colonoscopy Endoscopy Endoscopy is an examination of internal structures using a flexible viewing tube (endoscope). Endoscopy can also be used to treat many disorders because doctors are able to pass instruments... read more (an examination of the large intestine with a flexible viewing tube) and a biopsy (removal of a tissue specimen for microscopic examination). If Crohn disease is limited to the small intestine, colonoscopy will not detect the disease unless the colonoscope is advanced all the way through the colon and into the last part of the small intestine where the inflammation most often resides.
Prognosis for Crohn Disease
Crohn disease has no known cure and is characterized by intermittent flare-ups of symptoms. Flare-ups may be mild or severe, few or frequent. With proper treatment, most people continue to lead productive lives. However, about 10% of people with Crohn disease are disabled by the disease and its complications.
Treatment of Crohn Disease
Many treatments of Crohn disease help reduce inflammation and relieve symptoms.
Cramps and diarrhea may be relieved by taking loperamide or drugs that stop spasms in the abdomen (ideally before meals). Methylcellulose or psyllium preparations sometimes help prevent anal irritation by making the stool firmer. People should avoid eating fiber during flare-ups or if they have intestinal blockage.
Routine health maintenance measures Health maintenance In inflammatory bowel diseases, the intestine (bowel) becomes inflamed, often causing recurring abdominal pain and diarrhea. The two primary types of inflammatory bowel disease (IBD) are Crohn... read more , particularly vaccinations and cancer screening, are important.
These drugs, which may relieve cramps and diarrhea, include diphenoxylate, loperamide, deodorized opium tincture, and codeine. They are taken by mouth—preferably before meals.
Aminosalicylates are drugs used to treat inflammation caused by inflammatory bowel disease. Sulfasalazine and related drugs such as mesalamine, olsalazine, and balsalazide are types of aminosalicylates. These drugs can suppress symptoms when they occur and reduce inflammation, especially in the large intestine. Typically these drugs are taken by mouth. Mesalamine is also available as a suppository or enema. Aminosalicylates do not work as well for relieving severe flare-ups.
Corticosteroids, such as methylprednisolone, that are given by vein (intravenously) may dramatically reduce fever and diarrhea, relieve abdominal pain and tenderness, and improve appetite and sense of well-being in hospitalized people. However, long-term use of corticosteroids causes side effects ( see Corticosteroids: Uses and Side Effects Corticosteroids: Uses and Side Effects ). Usually, high doses are taken initially to relieve major inflammation and symptoms caused by sudden flare-ups. The dose is then reduced and the drug is discontinued as soon as possible.
Another corticosteroid called budesonide has fewer side effects than prednisone, but it may not be quite as rapidly effective and usually does not prevent relapses beyond 6 months. Budesonide can be given by mouth or as an enema.
As with corticosteroids taken by mouth, the dose of corticosteroids taken in enema or foam form (such as hydrocortisone) is reduced and gradually stopped.
If the disease becomes severe, the person is hospitalized and corticosteroids are given by vein (intravenously).
Doctors give vitamin D and calcium supplements to all people who take corticosteroids.
Azathioprine and mercaptopurine are drugs that decrease the actions of the immune system. They are effective for people with Crohn disease who do not respond to other drugs and are especially effective for maintaining long periods of remission (periods of no symptoms). They significantly improve the person's overall condition, decrease the need for corticosteroids, and often heal fistulas. However, these drugs may not produce benefits for 1 to 3 months and may have potentially serious side effects.
The most common side effects of azathioprine and mercaptopurine are nausea, vomiting, and a general feeling of illness (malaise). A doctor closely monitors the person for other side effects such as allergic reactions, suppression of bone marrow (monitored by regularly measuring white blood cell counts), inflammation of the pancreas ( pancreatitis Overview of Pancreatitis Pancreatitis is inflammation of the pancreas. The pancreas is a leaf-shaped organ about 5 inches (about 13 centimeters) long. It is surrounded by the lower edge of the stomach and the first... read more ), and sometimes liver problems. People who take these drugs have an increased risk of developing lymphoma Overview of Lymphoma Lymphomas are cancers of lymphocytes, which reside in the lymphatic system and in blood-forming organs. Lymphomas are cancers of a specific type of white blood cells known as lymphocytes. These... read more , a cancer of white blood cells, and some types of skin cancer (monitored by routine skin examinations).
Blood tests that detect variations in one of the enzymes that metabolize azathioprine and mercaptopurine and that directly measure metabolite levels often help the doctor ensure safe and effective drug dosages.
Methotrexate, given by injection or taken by mouth once a week, often benefits people who do not respond to or who cannot tolerate corticosteroids, azathioprine, or mercaptopurine. Side effects include nausea, vomiting, hair loss, liver problems, kidney failure, and rarely lung problems. A low white blood cell count can also occur, and thus people taking methotrexate are susceptible to infection. Methotrexate is teratogenic (dangerous to a fetus) and hence not used in pregnancy. Both women and men taking methotrexate should make sure the female partner uses an effective contraceptive method Overview of Contraception Contraception is prevention of fertilization of an egg by a sperm (conception) or prevention of attachment of the fertilized egg to the lining of the uterus ( implantation). Contraception (birth... read more (birth control) such as an intrauterine device Intrauterine Devices (IUDs) Intrauterine devices (IUDs) are small, flexible, T-shaped plastic devices that are inserted into the uterus. An IUD is left in place for 3, 5, 7, or 10 years, depending on the type, or until... read more (IUD), a contraceptive implant Contraceptive Implants Contraceptive hormones can be Taken by mouth (oral contraceptives) Inserted into the vagina (vaginal rings) Applied to the skin (patch) Implanted under the skin read more , or an oral contraceptive Oral Contraceptives Contraceptive hormones can be Taken by mouth (oral contraceptives) Inserted into the vagina (vaginal rings) Applied to the skin (patch) Implanted under the skin read more . Less effective methods of contraception, such as condoms, spermicides, diaphragms, cervical caps, and periodic abstinence, are discouraged. Doctors prescribe folic acid to decrease the side effects of methotrexate.
Cyclosporine is given by injection in high doses. This drug may help heal fistulas caused by Crohn disease, but it cannot safely be used long term because of side effects such as kidney problems, infections, and seizures.
Tacrolimus is given by mouth. This drug may help heal fistulas caused by Crohn disease. Side effects are similar to those of cyclosporine.
Infliximab, which is derived from monoclonal antibodies Monoclonal Antibodies Immunotherapy is the use of drugs that mimic or modify components of the immune system (such as tumor antigens and immune checkpoints—see also Overview of the Immune System) to fight disease... read more to tumor necrosis factor (called a tumor necrosis factor inhibitor or TNF inhibitor), is another modifier of the immune system's actions. Infliximab is given as a series of infusions by vein. This drug can be given to treat moderate to severe Crohn disease that has not responded to other drugs, to treat people with fistulas, and to maintain response when the disease is difficult to control.
Side effects that may occur with infliximab include worsening of an existing uncontrolled bacterial infection, reactivation of tuberculosis or hepatitis B, and an increase in the risk of some types of cancer. Some people have reactions such as fever, chills, nausea, headache, itching, or rash during the infusion (called infusion reactions). Before starting treatment with infliximab (or other TNF inhibitors such as adalimumab and certolizumab), people must be tested for tuberculosis and hepatitis B infection.
Adalimumab is a drug related to infliximab and also focuses on regulating the immune system. Adalimumab is given as a series of injections under the skin (subcutaneous injections) and so does not cause the possible infusion reactions of a drug given by vein such as infliximab. Adalimumab is particularly helpful for people who cannot tolerate or who no longer respond to infliximab. People may have pain and itching at the injection site.
Certolizumab is given as monthly subcutaneous injections. This drug works in a similar way as and causes side effects similar to those of infliximab and adalimumab.
Vedolizumab and natalizumab are drugs for people who have moderate to severe Crohn disease that has not responded to TNF inhibitors or other immunomodulating drugs or who are unable to tolerate these drugs. The most serious side effect they cause is infection. Natalizumab is currently available only through a restricted-use program because it increases the risk of a fatal brain infection called progressive multifocal leukoencephalopathy Progressive Multifocal Leukoencephalopathy (PML) Progressive multifocal leukoencephalopathy is a rare infection of the brain that is caused by the JC (John Cunningham) virus. People with a weakened immune system are most likely to get the... read more (PML). Vedolizumab has a theoretical risk of PML because it is in the same class of drugs as natalizumab.
Ustekinumab is another kind of biologic agent. The first dose is given by vein and then by injections under the skin every 8 weeks. Side effects include injection site reactions (pain, redness, swelling), cold-like symptoms, chills, and headache.
Broad-spectrum antibiotics and probiotics
Antibiotics that are effective against many types of bacteria are often prescribed. The antibiotic metronidazole is the most common choice for the treatment of abscesses and fistulas around the anus. Metronidazole may also help relieve the noninfectious symptoms of Crohn disease, such as diarrhea and abdominal cramps. However, when used for a long time, metronidazole can damage nerves, resulting in a pins-and-needles feeling in the arms and legs. This side effect usually disappears when the drug is stopped, but relapses of Crohn disease after discontinuing metronidazole are common.
People should avoid consuming alcoholic beverages or products containing propylene glycol while taking metronidazole and should continue to avoid these substances for at least 3 days after metronidazole treatment is completed.
Some other antibiotics, such as ciprofloxacin or levofloxacin, may be used in place of or in combination with metronidazole. Rifaximin, a nonabsorbable antibiotic, is also sometimes used in treating active Crohn disease.
Some bacteria are naturally found in the body and promote the growth of good bacteria (probiotics). The daily use of probiotics, such as lactobacillus (typically present in yogurt), may be effective in preventing pouchitis (inflammation of a reservoir created during surgical removal of the large intestine and rectum).
Although some people claim that certain diets have helped improve their IBD, diets have not been shown to be effective in clinical trials What Participants Need to Know About Clinical Trials People expect doctors to use treatments that work well and to stop using those that do not. However, it is often difficult for doctors and other scientists to tell which treatments work. Making... read more . Nutritional therapy may help children grow more than they might otherwise, especially when given at nighttime by tube feeding. Occasionally, concentrated nutrients are given intravenously to compensate for the poor absorption of nutrients that is typical of Crohn disease.
Most people with Crohn disease require surgery at some point during their illness. Surgery is needed when the intestine is obstructed or when abscesses or fistulas do not heal. An operation to remove diseased sections of the intestine may relieve symptoms indefinitely, but it does not cure the disease. Crohn disease tends to recur where the remaining intestine is rejoined, although several drug therapies initiated after surgery reduce this tendency.
A second operation is ultimately needed in nearly half of the people. Consequently, surgery is done only if specific complications or the failure of drug treatment makes it necessary. Still, most people who have undergone surgery consider their quality of life to be better than it was before the operation.
Because smoking increases the risk of recurrence, especially in women, doctors encourage people to quit smoking Smoking Cessation While often very challenging, quitting smoking is one of the most important things smokers can do for their health. Quitting smoking brings immediate health benefits that increase over time... read more .
People who have severe disease may be hospitalized and given intravenous fluids to restore and maintain body fluids (hydration). Some people who have heavy rectal bleeding may require blood transfusions. People who have more chronic anemia may need iron supplements taken by mouth or given intravenously.
Severity of symptoms
For people who have mild to moderate symptoms, mesalamine is typically the first drug of choice. Some doctors give antibiotics instead of mesalamine or give antibiotics to people who are not helped by mesalamine.
For people who have moderate to severe symptoms, corticosteroids (such as prednisone or budesonide) are given by mouth or vein for short periods of time.
People who are not helped by corticosteroids are given other drugs such as azathioprine, mercaptopurine, methotrexate, infliximab, adalimumab, certolizumab, vedolizumab, or ustekinumab. A combination of these drugs may be given. These drugs help most people.
If people have a blockage, doctors do nasogastric suction and give fluids by vein. In nasogastric suction, a tube is passed through the nose into the stomach or small intestine, and suction is applied to the tube to relieve abdominal swelling (distention).
For people whose symptoms developed suddenly or who have an abscess, fluids and antibiotics are given by vein in a hospital. Doctors drain the abscess surgically or by inserting a needle under the skin and drawing out the fluid.
People with fistulas around the anus (perianal fistulas Anorectal Fistula An anorectal fistula is an abnormal channel that leads from the anus or rectum usually to the skin near the anus but occasionally to another organ, such as the vagina. Anorectal fistulas are... read more ) are given metronidazole and ciprofloxacin. If these drugs do not help people in 3 to 4 weeks, doctors may give azathioprine, mercaptopurine, or biologic agents Biologic agents Crohn disease is an inflammatory bowel disease where chronic inflammation typically involves the lower part of the small intestine, the large intestine, or both and may affect any part of the... read more . Cyclosporine is an alternative, but fistulas often recur after treatment. Tacrolimus may help heal fistulas caused by Crohn disease. People may need definitive surgery to prevent the fistulas from recurring.
To help keep symptoms from returning (that is, to maintain remission), people who require only an aminosalicylate or antibiotic to achieve remission can continue to take these drugs. People who were treated with a combination of drugs such as azathioprine, mercaptopurine, methotrexate, infliximab, adalimumab, certolizumab, vedolizumab, and/or ustekinumab need to continue taking these drugs to maintain remission. People being treated with corticosteroids should have their doses gradually reduced. To maintain remission, they may need a combination of the drugs mentioned here.
During remission, doctors monitor people's symptoms and do blood tests. Routine x-rays or colonoscopy does not need to be done (except in people who have had Crohn disease for 7 or 8 years or longer).
The following are some English-language resources that may be useful. Please note that THE MANUAL is not responsible for the content of these resources.
Crohn's and Colitis Foundation of America: General information on Crohn disease and ulcerative colitis, including access to support services
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)—Crohn's Disease: General information on Crohn disease, including information about research and clinical trials