IBS and Microscopic Colitis

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Both IBS and microscopic colitis share the symptom of chronic diarrhea, so it's understandable to wonder if they are related. The treatment for the two conditions is very different, so you will want to be assured that you have the right diagnosis.

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What Is Microscopic Colitis?

Microscopic colitis is a condition in which a person experiences chronic watery, but not bloody, diarrhea. The disease is more likely to affect women than men and risk goes up with age; the highest incidence is seen in people who are in their 60s or 70s.

There are two types of microscopic colitis: collagenous colitis and lymphocytic colitis. They differ in terms of the way they look during a diagnostic evaluation:

  • In lymphocytic colitis, there is an increased number of white blood cells present in the tissue of the lining of the colon.
  • In collagenous colitis, a thick layer of collagen is seen in the tissue.

That said, they are possibly just two different stages of the same disorder. Regardless of type, the two disorders are diagnosed and treated the same way.

Microscopic Colitis Symptoms

In addition to the symptom of chronic watery diarrhea, microscopic colitis may also result in:

Symptoms may be intermittent and, at times, the disease can resolve on its own without any medical treatment.


No one knows for sure what causes microscopic colitis. Risk factors include:


Similar to IBS, with microscopic colitis, there will generally be no sign of the disease seen during a colonoscopy. Where the two disorders differ is that microscopic colitis will show up when a sample of colonic tissue is looked at under a microscope.

In addition to a colonoscopy with biopsy, other tests will be given to rule out other diseases. Blood work, with possible endoscopy, will be recommended to rule out celiac disease. A stool test may be recommended to identify any pathogens that might be causing diarrhea.


The treatment options for microscopic colitis are very different than the treatment options for IBS.

The first step may be to stop smoking or discontinue any medications that are suspected to be contributing to the disease.

Medication to treat microscopic colitis may be prescribed. Multiple medications have been used with variable degrees of success, including:

At its worst, microscopic colitis may be addressed through ileostomy surgery.

IBS vs. Microscopic Colitis

Having learned about microscopic colitis, you still may be wondering if you have the correct diagnosis.

A meta-analysis concluded that while around one-third of people who have microscopic colitis report IBS symptoms, the same is true of those who do not have microscopic colitis.

According to the review, the overlap between IBS and microscopic colitis differed based on study design. In case-control studies, microscopic colitis was seen more often in people who have IBS than those who had no symptoms.

But in studies that looked at evidence across large groups, people who have IBS are no more likely to have microscopic colitis than people who don't.

Based on this meta-analysis, the authors recommend that unless you are at higher risk for microscopic colitis or any red-flag digestive symptoms, there is no need for a person with IBS to undergo a colonoscopy to rule out microscopic colitis.

Of course, if your IBS symptoms change, you should inform your healthcare provider with the expectation that further testing may be needed to either confirm your diagnosis or obtain an accurate one.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  3. Hempel KA, Sharma AV. Collagenous and lymphocytic colitis. In: StatPearls [Internet].

  4. Rasmussen MA, Munck LK. Systematic review: are lymphocytic colitis and collagenous colitis two subtypes of the same disease - microscopic colitis? Aliment Pharmacol Ther. 2012 Jul;36(2):79-90. doi:10.1111/j.1365-2036.2012.05166.x

  5. Boland K, Nguyen GC. Microscopic colitis: a review of collagenous and lymphocytic colitis. Gastroenterol Hepatol (N Y). 2017 Nov;13(11):671-7.

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  7. Kamp EJCA, Kane JS, Ford AC. Irritable bowel syndrome and microscopic colitis: a systematic review and meta-analysis. Clin Gastroenterol Hepatol. 2016 May;14(5):659-68.e1. doi:10.1016/j.cgh.2015.09.031

By Barbara Bolen, PhD
Barbara Bolen, PhD, is a licensed clinical psychologist and health coach. She has written multiple books focused on living with irritable bowel syndrome.