National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Crohn's disease

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Not a rare disease Not a rare disease
Other Names:
Ileitis; Enteritis; Granulomatous colitis; Ileitis; Enteritis; Granulomatous colitis; Granulomatous enteritis See More
Categories:
Crohn's disease is a type of inflammatory bowel disease (IBD), the general name for conditions that cause inflammation in the gastrointestinal (GI) tract. Common signs and symptoms include abdominal pain and cramping, diarrhea, and weight loss. Other general symptoms include feeling tired, nausea and loss of appetite, fever, and anemia. Complications of Crohn's disease may include intestinal blockage, fistulas, anal fissures, ulcers, malnutrition, and inflammation in other areas of the body. Crohn's disease can occur in people of all age groups but is most often diagnosed in young adults.[1][2] The exact cause is unknown, but is thought to be due from a combination of certain genetic variations, changes in the immune system, and the presence of bacteria in the digestive tract.[1][2][3]  Many of the major genes related to Crohn disease, including NOD2, ATG16L1, IL23R, and IRGM, are involved in immune system function. The disease is not inherited but it appears to run in some families because in about 15% of the cases the disease is present in more than one relative.[3] 

Treatment is aimed at relieving symptoms and reducing inflammation, and may include diet and medication, but some people require surgery.[1][2] Surgery often involves removal of the diseased segment of bowel (resection), the two ends of healthy bowel are then joined together (anastomosis). In about 30% of people who have surgery for Crohn’s disease symptoms may come back within three years and up to 60% will have recurrence within ten years.[4]
Last updated: 5/11/2018
Crohn's disease causes inflammation of the digestive or gastrointestinal (GI) tract. It usually 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 inflammation extends deep into the lining of the affected organ, which can cause abdominal pain and diarrhea.[1] Affected individuals may also have loss of appetite, weight loss, and fever.[3]

About one-third of individuals with Crohn's disease have symptoms outside of the intestines, which may include arthritis, uveitis (inflammation of the covering of the eye), skin lesions, and sacroilitis (inflammation of the large joints of the tail bone and pelvis).[5]

Symptoms of Crohn's disease may range from mild to severe. Most people will go through periods in which the disease flares up and causes symptoms, alternating with periods when symptoms disappear or decrease. People with Crohn’s disease who smoke tend to have more severe symptoms and more complications. In general, people with Crohn's disease lead active and productive lives.[1][5]
Last updated: 11/15/2012

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Showing of 7 |
Medical Terms Other Names
Learn More:
HPO ID
Percent of people who have these symptoms is not available through HPO
Abdominal pain
Pain in stomach
Stomach pain
[ more ] 		0002027
Diarrhea
Watery stool
0002014
Growth delay
Delayed growth
Growth deficiency
Growth failure
Growth retardation
Poor growth
Retarded growth
[ more ] 		0001510
Intestinal obstruction
Bowel obstruction
Intestinal blockage
[ more ] 		0005214
Multifactorial inheritance 0001426
Ulcerative colitis 0100279
Weight loss 0001824
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Last updated: 7/1/2020
The exact cause of Crohn's disease is not known, but it appears to be a multifactorial condition. This means that both genetic and environmental factors likely interact to predispose an individual to being affected. Studies suggest that Crohn's disease may result from a combination of certain genetic variations, changes in the immune system, and the presence of bacteria in the digestive tract.[3]

Recent studies have found that variations in specific genes, including the ATG16L1, IL23R, IRGM, and NOD2 genes, influence the risk of developing Crohn's disease. These genes provide instructions for making proteins that are involved in immune system function. Variations in any of these genes may disrupt the ability of intestinal cells to respond to bacteria, leading to chronic inflammation and thus the signs and symptoms of the condition. There may also be genetic variations in regions of chromosome 5 and chromosome 10 that contribute to an increased risk to develop Crohn's disease.[3]
Last updated: 10/15/2012
Crohn's disease, like most other autoimmune diseases, is thought to be a multifactorial condition. This means it is likely associated with the effects of multiple genes, in combination with lifestyle and environmental factors.[6] Once an autoimmune disease is present in a family, other relatives may be at risk to develop the same autoimmune disease, or a different autoimmune disease. However, if an autoimmune diseases such as Crohn's disease occurs in a family, it does not necessarily mean that relatives will develop an autoimmune disease.[7] Having an affected family member means that there may be a genetic predisposition in the family that could increase an individual's chance of developing an autoimmune disease. Thus, having an affected family member is considered a risk factor for Crohn's disease.[8]
Last updated: 10/15/2012
A variety of tests are used to diagnose and monitor Crohn’s disease. A combination of tests is often needed because some symptoms of the condition are similar to other intestinal disorders such as irritable bowel syndrome and to another type of inflammatory bowel disease (IBD) called ulcerative colitis.[1] Tests used to narrow down the diagnosis may include blood tests, tissue tests, ultrasound, x-rays, CT scan, and/or endoscopy. A proper diagnosis also involves identifying the extent and severity of disease as well as any related complications.[9]
Last updated: 10/15/2012

For information on the treatment of Crohn's disease, visit the following links:

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK): 
https://www.niddk.nih.gov/health-information/health-topics/digestive-diseases/crohns-disease/Pages/treatment.aspx

Crohn's & Colitis Foundation of America: 
http://www.ccfa.org/what-are-crohns-and-colitis/what-is-crohns-disease/crohns-treatment-options.html

Complementary and Alternative Medicine (CAM) for Crohn's disease from the Crohn's & Colitis Foundation of America: 
http://www.ccfa.org/resources/complementary-alternative.html

Last updated: 11/15/2012

FDA-Approved Treatments

The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for treatment of this condition. Learn more orphan products.

  • Adalimumab (Brand name: Humira) - Manufactured by AbbVie Inc.
    FDA-approved indication: Treatment of Juvenile Idiopathic Arthritis. Reducing signs and symptoms and inducing and maintaining clinical remission in patients 6 years of age and older with moderately to severely active Crohn's disease who have had an inadequate response to corticosteroids or immunomodulators such as azathioprine, 6-mercaptopurine, or methotrexate.
    National Library of Medicine Drug Information Portal
    Medline Plus Health Information
  • Infliximab (Brand name: Remicade) - Manufactured by Centocor, Inc.
    FDA-approved indication: For reducing signs and symptoms and inducing and maintaining clinical remission in pediatric patients with moderately to severely active Crohn's disease who have had an inadequate response to conventional therapy.
    National Library of Medicine Drug Information Portal
    Medline Plus Health Information
Crohn's disease may affect as many as 700,000 people in the U.S. Men and women are affected in equal numbers. While the condition can occur at any age, it is more common among adolescents and young adults between the ages of 15 and 35.
Last updated: 3/15/2016

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • ClinicalTrials.gov lists trials that are related to Crohn's disease. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

Patient Registry

  • The Autoimmune Registry supports research for Crohn's disease by collecting information about patients with this and other autoimmune diseases. You can join the registry to share your information with researchers and receive updates about participating in new research studies. Learn more about registries.

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

Living with a genetic or rare disease can impact the daily lives of patients and families. These resources can help families navigate various aspects of living with a rare disease.

Financial Resources

  • Patient Access Network Foundation (PAN Foundation) has Assistance Programs for those with health insurance who reside in the United States. The disease fund status can change over time, so you may need to check back if funds are not currently available. 
  • The Assistance Fund provides various services, including education and financial aid, to help patients with a chronic or serious illness cover the cost of FDA-approved medications. Patients must be U.S citizens or permanent residents.

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • Just Like Me! , a Web site for kids and teens with ulcerative colitis or Crohn's disease sponsored by the Crohn's & Colitis Foundation of America (CCFA).
  • Genetics Home Reference (GHR) contains information on Crohn's disease. This website is maintained by the National Library of Medicine.
  • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
  • The Merck Manuals Online Medical Library provides information on this condition for patients and caregivers. 
  • The National Digestive Diseases Information Clearinghouse (NIDDK) offers information on this condition. Click on the link to view information on this topic.

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Crohn's disease. Click on the link to view a sample search on this topic.

Other Conferences

  • !LINK!, April 19, 2013 - April 20, 2013
    Location: Froedtert and Medical College of Wisconsin, Milwaukee, WI
    Description: The aim of this NIH workshop is to break the stalemate and facilitate interdisciplinary collaboration by creating functional clinical research teams on the national level who can then create a momentum for progress in this area of substantial unmet need and high promise. The CIBMTR infrastructure, which is currently cancer-focused, can be easily adapted to collect AID-specific data

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question

  • Where can I get a complete list of all genes that have been associated with Crohn's disease? See answer

  • I have a friend whose husband has Crohn's disease. She may be pregnant and is wondering what the likelihood is that her baby will have this disease.  Is there a test that can diagnose Crohn's disease during pregnancy? See answer

  • How might Crohn's disease be treated? See answer

  • My father has Crohn's disease for which he has had many surgeries in his lifetime. His brother (my uncle) also had this disease as a young adult.  Can you tell me what percent chance I would have of having this disease as well? My fathers other young adult children do not have it as of yet. See answer


  1. Crohn's disease. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). September 2014; http://www.niddk.nih.gov/health-information/health-topics/digestive-diseases/crohns-disease/Pages/facts.aspx.
  2. Walfish AE & Sachar DB. Crohn Disease. Merck Manual Consumer Version. 2017; http://www.merckmanuals.com/home/digestive-disorders/inflammatory-bowel-diseases-ibd/crohn-disease?qt=&sc=&alt=.
  3. Crohn disease. Genetics Home Reference. 2018; http://ghr.nlm.nih.gov/condition/crohn-disease.
  4. What is Crohn's Disease?. Crohn's & Colitis Foundation of America. 2016; http://www.ccfa.org/what-are-crohns-and-colitis/what-is-crohns-disease/.
  5. Cummings S, Rubin D. The Complexity and Challenges of Genetic Counseling and Testing for Inflammatory Bowel Disease. Journal of Genetic Counseling. December 2006;
  6. What are complex or multifactorial disorders?. Genetics Home Reference. October 8, 2012; http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/complexdisorders. Accessed 10/15/2012.
  7. Department of Human Genetics. Autoimmune disorders. Emory University School of Medicine. 2004; http://genetics.emory.edu/documents/resources/Emory_Human_Genetics_Autoimmune_Disorders.pdf. Accessed 2/7/2012.
  8. Crohn Disease. Genetics Home Reference (GHR) . August 2007; http://ghr.nlm.nih.gov/condition=crohndisease. Accessed 2/7/2012.
  9. Diagnosing Crohn's Disease and Ulcerative Colitis. Crohn's & Colitis Foundation of America. May 31, 2010; http://www.ccfa.org/resources/diagnosing-crohns-uc.html. Accessed 10/15/2012.