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Overview of Inflammatory Bowel Disease (IBD)

By Aaron E. Walfish, MD, Clinical Assistant Professor, Mount Sinai Medical Center ; Rafael Antonio Ching Companioni, MD, Icahn School of Medicine, Elmhurst Hospital Center

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In inflammatory bowel diseases, the intestine (bowel) becomes inflamed, often causing recurring abdominal cramps and diarrhea.

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

These two 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 inflammatory bowel disease is not known, but evidence suggests that normal intestinal bacteria trigger an abnormal immune reaction in people with a genetic predisposition.

Inflammatory bowel disease 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 and is 2 to 4 times more common among Ashkenazi Jews than non-Jewish whites who live in 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.


The symptoms of inflammatory bowel disease 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 cramps and bloody diarrhea. In both diseases, people with longstanding diarrhea may lose weight and become undernourished.

Sometimes IBD causes inflammation in 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.


  • Stool and blood tests

  • Tissue biopsy

To make a diagnosis of inflammatory bowel disease, 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 (Clostridium difficile infection) that can result from antibiotic use.

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

Tissue samples may be taken from the lining of the rectum during sigmoidoscopy (an examination of the sigmoid colon using a viewing tube) and examined microscopically for evidence of other causes of colon inflammation (colitis). 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, certain gynecologic disorders in women, and celiac disease. 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 Crohn disease.


  • Drugs

  • Sometimes surgery

  • Diet and stress management

Although there is no cure for IBD, many drugs (see Table: Drugs That Reduce Bowel Inflammation Caused by Crohn Disease and see Table: Drugs That Reduce Bowel Inflammation Caused by Ulcerative Colitis), including aminosalicylates, corticosteroids, immunomodulating drugs, biologic 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.

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