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IBD: What Happens When Your Intestines Are Inflamed?

Ask a Doctor

I typically eat a healthy diet and I’m a normal weight. I’m not athlete, but I try to exercise a few times a week. Despite all this, I started having stomach pain and diarrhea, and my doctor finally diagnosed me with inflammatory bowel disease. Why did I get IBD? What causes IBD? What happens when your intestines are inflamed?

Doctor’s Response

Researchers do not yet know what causes inflammatory bowel disease. Therefore, IBD is called an idiopathic disease (disease with an unknown cause).

An unknown factor/agent (or a combination of factors) triggers the body's immune system to produce an inflammatory reaction in the intestinal tract that continues without control. As a result of the inflammatory reaction, the intestinal wall is damaged leading to bloody diarrhea and abdominal pain.

Genetic, infectious, immunologic, and psychological factors have all been associated with influencing the development of IBD.

There is a genetic predisposition (or perhaps susceptibility) to the development of IBD, but the triggering factor for the activation of the body's immune system has yet to be identified. Factors that can turn on the body's immune system include an infectious agent (as yet unidentified), an immune response to an antigen (for example, protein from cow milk), or an autoimmune process. As the intestines are always exposed to things that can cause immune reactions, more recent thinking is that there is a failure of the body to turn off the normal immune responses.

Intestinal complications of inflammatory bowel disease include the following:

  • Profuse bleeding from the ulcers
  • Perforation (rupture) of the bowel
  • Strictures and obstruction: In persons with Crohn's disease, narrowing of the intestines due to inflammation occurs, and frequently resolves with medical treatment.

Fixed or fibrotic (scarring) strictures may require endoscopic or surgical intervention to relieve the obstruction. In ulcerative colitis, colonic strictures should be presumed to be malignant (cancerous).

  • Fistulae (abnormal passage) and perianal disease: These are more common in persons with Crohn's disease. They may not respond to vigorous medical treatment. Surgical intervention often is required, and there is a high risk of recurrence.
  • Toxic mega-colon (acute without obstructive dilation of the colon): Although rare, toxic mega colon is a life-threatening complication of ulcerative colitis and requires urgent surgical intervention.
  • Malignancy: The risk of colon cancer in ulcerative colitis begins to rise significantly above that of the general population after approximately 8 to 10 years of diagnosis. The risk of cancer in Crohn's disease may equal that of ulcerative colitis if the entire colon is involved. The risk of small intestine malignancy is increased in Crohn's disease.

Extraintestinal Complications

  • Extraintestinal involvement of IBD refers to complications involving organs other than the intestines. These affect only a small percentage of people with IBD.
  • Persons with IBD may have:
  • Of all the extraintestinal complications, arthritis is the most common. Joint, eye, and skin complications often occur together.

Health Solutions From Our Sponsors

Crohn's & Colitis Foundation of America. "IBS and IBD: Two Very Different Disorders." Published June 1, 2012.

Crohn's & Colitis Foundation of America. "What are Crohn's & Colitis?

Farrell, R.J., MD., et al. "Overview of the medical management of mild to moderate Crohn disease in adults." UpToDate. Updated: Jul 28, 2016.

Rowe, W.A., MD. "Inflammatory Bowel Disease." Medscape. Updated: Jun 17, 2016.

Peppercorn, M.A., MD., et al. "Definition, epidemiology, and risk factors in inflammatory bowel disease." UpToDate. Updated: Nov 08, 2016.