Is There a Connection Between IBS and Colitis?

Colitis is defined as an infection of the large intestine. Such an infection can result in symptoms that are similar to those seen in irritable bowel syndrome (IBS). This begs the question, is there an overlap or connection between IBS and colitis? This overview will cover some of the more common forms of colitis in terms of how they may or may not be related to IBS.

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Ulcerative Colitis and IBS

Ulcerative colitis is one of the two inflammatory bowel diseases (IBDs).

Shared Symptoms of Ulcerative Colitis and IBS

The following symptoms are shared by the two different health conditions:

Symptoms Unique to Ulcerative Colitis

The following symptoms are not typical for IBS but are likely to be experienced by a person who has ulcerative colitis.

  • Blood in the stool
  • Fever
  • Significant loss of appetite (more than can be explained by food avoidance for fear of setting off symptoms)
  • Visible signs of ulceration on the lining of the large intestine

What Causes Ulcerative Colitis?

Overlap Between IBD and IBS

Although the two disorders have traditionally been seen as distinct in terms of both presentation and cause, some researchers are putting forth theories that perhaps the two diagnoses are actually at different ends of the same spectrum.

Some studies have shown that people who have IBS are at higher risk to eventually be diagnosed with IBD (ulcerative colitis or Crohn's disease). One group of researchers found that this higher risk may be associated with having experienced infectious gastroenteritis (stomach "flu" caused by an infectious bacteria or virus).

Microscopic Colitis and IBS

Microscopic colitis is a disease in which a person experiences symptoms of chronic watery diarrhea. The disease differs from IBS in that signs of infection can be seen when intestinal cells are examined under a microscope.

Shared Symptoms of Microscopic Colitis and IBS

Symptoms Unique to Microscopic Colitis

  • Nausea
  • Weight loss

Infectious Colitis and IBS

Infectious colitis is an illness that is caused by an infectious agent, such as:

  • Campylobacter
  • E. coli
  • Salmonella
  • Shigella

Symptoms of Infectious Colitis

As you can see, the symptoms of infectious colitis are quite different from those of IBS:

  • Bloody diarrhea
  • Chills
  • Fever

Inflammation in IBS

Although the diagnosis of IBS requires that there be no visible signs of inflammation, researchers are increasingly finding evidence that inflammation does play a role in the symptoms of IBS. This inflammation in the cells lining the large intestine is not visible, as is the case with ulcerative colitis, nor can it be seen with a microscope as is the case with microscopic colitis. Instead, this inflammation is considered to be low-grade and requires an in-depth examination of tissue to identify its presence. Further information about the role of inflammation opens up the promise of more effective treatment options for IBS.

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