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Crohn's Disease

A form of inflammatory bowel disease that causes irritation in the gastrointestinal (GI) tract. It usually affects the lower small intestine (also called the ileum) or the colon, but it can also affect any part of the GI tract.

PubMed Health Glossary
(Source: NIH - National Institute of Diabetes and Digestive and Kidney Diseases)

About Crohn's Disease

Crohn's disease is a disease that causes inflammation, or swelling, and irritation of any part of the digestive tract—also called the gastrointestinal (GI) tract. The part most commonly affected is the end part of the small intestine, called the ileum.

The GI tract is a series of hollow organs joined in a long, twisting tube from the mouth to the anus. The movement of muscles in the GI tract, along with the release of hormones and enzymes, allows for the digestion of food.

In Crohn's disease, inflammation extends deep into the lining of the affected part of the GI tract. Swelling can cause pain and can make the intestine—also called the bowel—empty frequently, resulting in diarrhea. Chronic—or long-lasting—inflammation may produce scar tissue that builds up inside the intestine to create a stricture. A stricture is a narrowed passageway that can slow the movement of food through the intestine, causing pain or cramps... NIH - National Institute of Diabetes and Digestive and Kidney Diseases

What works? Research summarized

Evidence reviews

Crohn's Disease: Management in Adults, Children and Young People

This guideline intends to show the place of both new and established treatments in the wider care pathway for Crohn's disease. This will be useful for clinicians and people with Crohn's disease because new drugs have been licensed for Crohn's disease in the last decade. The guideline also deals with those medications which are unlicensed for treatment of the condition, but which have been used in this way (off-label) for many years and their role is recognised in other NICE documents as well as the British National Formulary. They include azathioprine, mercaptopurine and methotrexate. The guideline aims to help improve the care offered to people with Crohn's disease and provide information about the clinical and cost effectiveness of potential care pathways. Management of Crohn's disease in specific populations (for example, in pregnancy) may require special consideration.

[Evaluation of the efficacy and safety of adalimumab in Crohn's disease]

Bibliographic details: Huang M, Ran Z, Xu X, Tong J, Xiao S.  [Evaluation of the efficacy and safety of adalimumab in Crohn's disease]. Chinese Journal of Gastroenterology 2011; 16(7): 413-418

Pharmacologic Therapies for the Management of Crohn's Disease: Comparative Effectiveness [Internet]

The purpose of this review was to compare the efficacy and safety of biologics, immunomodulators, corticosteroids, and aminosalicylates in the treatment of Crohn's disease.

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Summaries for consumers

Vedolizumab (Entyvio) for Crohn’s disease: Overview

Vedolizumab (trade name: Entyvio) has been approved in Germany since May 2014 for the treatment of moderate to severe Crohn’s disease.

Cyclosporine for treatment of active Crohn's disease

The results of this review demonstrate that low dose oral cyclosporine is not effective for treatment of active Crohn's disease. Studies indicate that Crohn's patients treated with low dose (5 mg/kg/day) oral cyclosporine could experience side effects including kidney problems. Therefore the use of this medication for the treatment of chronic active Crohn's disease is not advisable. Higher oral doses and injections of cyclosporine have not been sufficiently evaluated. Larger doses of cyclosporine are not likely to be useful for the long‐term management of Crohn's disease due to the risk of kidney damage and the availability of other proven medications.

Natalizumab for treatment of active Crohn's disease

Crohn's disease is a chronic inflammatory disease of the intestines. Crohn's disease frequently occurs in the lower part of the small intestine, called the ileum, but it can affect any part of the digestive tract, from the mouth to the anus. The most common symptoms of Crohn's disease are abdominal pain, often in the lower right area, and diarrhea. Natalizumab blocks the adhesion and migration of white blood cells into the gut reducing chronic inflammation associated with Crohn's disease. Four high quality studies were reviewed. The studies tested 1692 people over the age of eighteen who had moderate to severe Crohn's disease. The subjects received 1 to 3 infusions of natalizumab (at a dosage of 300 mg or weight based dosages of 3, 4 or 6 mg/kg) or placebo (fake infusions). The studies lasted for 12 weeks. The results of the studies indicate that natalizumab is effective therapy for some people with active Crohn's disease. People with active disease responded positively to even one treatment of the drug and the studies examined showed increased benefits with additional injections of natalizumab. More people improved through treatment using natalizumab than those using the fake treatments. The drug was generally well tolerated and side effects occurred infrequently. Serious side effects occurred rarely (range 7 to 11% for natalizumab and placebo patients). Few patients withdrew from the studies due to side effects (2 to 8% for natalizumab compared to 3 to 7% for placebo). Side effects that occurred during the trials included: headache, worsening of Crohn's disease, abdominal pain, arthralgia, colitis, influenza syndrome, infection, nausea, vomiting, fatigue, hypersensitivity‐like reactions, and the development of antibodies against natalizumab. Recently, it was found that two patients who received natalizumab in combination with interferon beta‐1 for multiple sclerosis and one patient who received natalizumab in combination with azathioprine for Crohn's disease developed a severe disease called progressive multifocal leukoencephalopathy (PML) resulting in two deaths. PML is a serious infection of the nervous system. However an investigation of more than 3500 patients who took natalizumab found no new cases of PML. It was discovered that PML is not always fatal and regular testing of patients could provide adequate safety and ensure the well‐being of those taking natalizumab. However, the benefits of natalizumab for people with Crohn's disease should be carefully weighed against the potential risk of serious adverse events such as the possibility of infection of the nervous system.

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More about Crohn's Disease

Photo of a young adult

Also called: Crohn's, Morbus Crohn, Granulomatous enteritis, Regional enteritis, Granulomatous colitis, Regional ileitis, Crohn disease

See Also: Ulcerative Colitis

Other terms to know:

Keep up with systematic reviews on Crohn's Disease:


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