Overview of Inflammatory Bowel Disease (IBD)

ByAaron E. Walfish, MD, Mount Sinai Medical Center;
Rafael Antonio Ching Companioni, MD, HCA Florida Gulf Coast Hospital
Reviewed/Revised Nov 2023
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In inflammatory bowel diseases, the intestine (bowel) becomes inflamed, often causing recurring abdominal pain and diarrhea.

The 2 primary types of inflammatory bowel disease (IBD) are

These 2 diseases have many similarities and sometimes are difficult to distinguish from each other. However, there are several differences. For example, Crohn disease can affect almost any part of the digestive tract, whereas ulcerative colitis almost always affects only the large intestine.

The cause of IBD is not known, but evidence suggests that normal intestinal bacteria inappropriately trigger an immune reaction in people with a genetic predisposition.

IBD affects people of all ages but usually begins before age 30, typically from age 14 to 24. A few people have their first attack between the ages of 50 and 70.

IBD is most common among people of Northern European and Anglo-Saxon descent. It is 2 to 4 times more common among people of Ashkenazi Jewish ancestry (those from Central or Eastern Europe) than non-Jewish White people from the same region. Both sexes are equally affected. First-degree relatives (mother, father, sister, or brother) of people with IBD have a 4- to 20-fold increased risk of developing IBD. The tendency to run in families is much higher in Crohn disease than ulcerative colitis.

Symptoms of Inflammatory Bowel Disease

The symptoms of IBD vary depending on which part of the intestine is affected and whether the person has Crohn disease or ulcerative colitis. People with Crohn disease usually have chronic diarrhea and abdominal pain. People with ulcerative colitis usually have intermittent episodes of abdominal pain and bloody diarrhea. In both diseases, people with longstanding diarrhea may lose weight and become undernourished.

Sometimes IBD can affect other parts of the body such as the joints, eyes, mouth, liver, gallbladder, and skin. IBD also increases the risk of cancer in areas of the intestine that are affected.

Did You Know...

  • Inflammatory bowel disease increases the risk of cancer in affected areas of the intestine.

Diagnosis of Inflammatory Bowel Disease

  • Stool and blood tests

  • Endoscopy with tissue biopsy

To make a diagnosis of IBD, a doctor must first exclude other possible causes of inflammation. For example, infection with parasites or bacteria may cause inflammation. Therefore, the doctor does several tests.

Stool samples are analyzed for evidence of a bacterial or parasitic infection (acquired during travel, for example), including a type of bacterial infection (Clostridioides difficile infection [formerly Clostridium difficile]) that can result from antibiotic use.

Tests may also be done to detect sexually transmitted infections of the rectum, such as gonorrhea, herpesvirus infection, and chlamydial infection.

Tissue samples may be taken from the lining of the digestive tract during endoscopy (an examination of the digestive tract using a viewing tube) and examined microscopically for evidence of other causes of inflammation of the colon (colitis) or inflammation of the last part of the small intestine (ileum). This removal and examination of tissue is called a biopsy.

Doctors also consider other disorders that cause similar abdominal symptoms such as irritable bowel syndrome, ischemic colitis (which occurs more often in people older than 50), malabsorption syndromes, including celiac disease, and certain gynecologic disorders in women. The doctor may do imaging studies, such as x-rays, computed tomography (CT), or magnetic resonance imaging (MRI) of the abdomen to rule out other disorders. The doctor may do video capsule endoscopy to evaluate the intestines of people who have symptoms that suggest Crohn disease.

Treatment of Inflammatory Bowel Disease

  • Medications

  • Sometimes surgery

  • Diet and stress management

Although there is no cure for IBD, many medications (see table Medications That Reduce Bowel Inflammation Caused by Crohn Disease and table Medications That Reduce Bowel Inflammation Caused by Ulcerative Colitis), including aminosalicylates, corticosteroids, immunomodulating medications, biologic agents, small-molecule agents and antibiotics, can help reduce inflammation and relieve the symptoms of IBD.

People with very severe disease sometimes need surgery.

Diet and stress management

Most people and their families are interested in diet and stress management. Although some people claim that certain diets have helped improve their IBD, including one with rigid carbohydrate restrictions, diets have not been shown to be effective in clinical trials. Doctors sometimes recommend stress-management techniques to help people deal with the stress of having a chronic disease.

Health maintenance

IBD puts people at increased risk of developing certain infections and disorders because of their underlying disease, poor nutrition, or use of immunomodulating medications. Vaccinations and diagnostic tests and screenings can help lessen the risk.

The influenza vaccine is needed every year to help protect against the flu. The pneumococcal vaccine helps protect against bacterial infections caused by Streptococcus pneumoniae. People who are age 19 and older should receive the shingles vaccine. The shingles vaccine should be given before people start taking immunomodulating medications whenever possible. People should also receive routine tetanus-diphtheria, hepatitis A, hepatitis B, and human papillomavirus vaccines if appropriate. COVID-19 vaccines that use mRNA are recommended for people who have IBD, including those who are taking immunomodulating medications.

Women who have IBD and who are taking immunomodulating medications should be screened for cervical cancer every year. Women who have IBD and who are not taking immunomodulating medications should have cervical cancer screening every 3 years.

People who have IBD and are taking or plan to take an immunomodulating medication or biologic agent should be screened for skin cancer every year and should use sunscreen and wear protective clothing.

People at risk of decreased bone density (osteoporosis) should have a dual-energy x-ray absorptiometry (DXA) scan.

More Information

The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.

  1. Crohn's and Colitis Foundation of America: General information on Crohn disease and ulcerative colitis, including access to support services

  2. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)—Crohn Disease: General information on Crohn disease, including information about research and clinical trials

  3. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)—Ulcerative Colitis: General information on ulcerative colitis, including information about research and clinical trials

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