Medical News Today: What is collagenous colitis?

Collagenous colitis refers to a type of microscopic colitis characterized by a thick band of collagen under the lining of the colon.

In this article, learn about the symptoms, causes, and treatment of collagenous colitis.

What is collagenous colitis?

High magnification micrograph of collagenous colitis. Image credit: Nephron, (2010, November 6)
Collagenous colitis is a type of inflammation that can only be seen under a microscope.
Image credit: Nephron, (2010, November 6)

Collagenous colitis is a type of microscopic colitis, characterized by a thick, non-elastic band of collagen under the lining of the colon. Collagen is a type of structural protein in the body.

It is described as a type of microscopic colitis because the inflammation it causes can only be seen under the microscope. Unlike most inflammatory bowel conditions, collagenous colitis is not considered a risk factor for colon cancer.

The term microscopic colitis usually refers to both collagenous colitis and lymphocytic colitis. Both conditions share the same signs, symptoms, diagnostic tests, and treatment process.

Some research also shows that collagenous colitis and lymphocytic colitis may, in fact, be different stages of the same condition.

Collagenous colitis is considered a rare disorder, with the highest incidence in adults over 45 years of age.

Only about 42 out of every 100,000 people are diagnosed with collagenous colitis.


The severity, frequency, and duration of collagenous colitis symptoms vary. People with this condition can experience flare-ups when they experience frequent symptoms, and periods of remission when they will have few or no symptoms.

While some people may have painful, disabling symptoms, others only experience mild discomfort. And, while many people experience flare-ups that last a few days or weeks, other people have symptoms that last for months to years.

Common symptoms of collagenous colitis include:

  • chronic watery, non-bloody diarrhea or loose stool, often between 3 and 20 times daily
  • abdominal cramping and pain
  • dehydration
  • weight loss
  • nausea and vomiting
  • bloating and gas
  • exhaustion
  • fecal incontinence or accidental stool passage, especially at night
  • reduced nutrition
  • anemia

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Shelf of packaged medication in pharmacty.
Certain medications, such as ibuprofen and statins, are thought to be potential causes for collagenous colitis.

Collagenous colitis affects the colon, which is the large intestine. The colon takes a liquid mixture of digested food from the small intestine and transforms it into a solid stool before delivering it to the rectum, for removal from the body.

Collagenous colitis causes general inflammation of the epithelium or base layer of cells that lining the colon.

Colon epithelial cells are vital to the organ’s overall performance because they help digestion and maintain the relationship between the body’s immune system and the healthful communities of microbes in the gut.

Trillions of microbes, such as bacteria and viruses, live in the gastrointestinal tract and aid in digestion.

When colon epithelial cells are damaged or destroyed, a variety of digestive symptoms occur. In cases of collagenous colitis, the layer of collagen — a connective tissue protein that helps support the epithelial cells — becomes roughly five times thicker than normal.

Much like many other inflammatory gastrointestinal conditions, researchers are not sure why collagenous colitis occurs. Most research indicates that it likely has a genetic basis and may be related to other autoimmune conditions.

Some of the proposed causes of collagenous colitis include:

Some of the medications most commonly associated with the development of collagenous colitis include:

  • non-steroidal anti-inflammatories (NSAIDs), such as ibuprofen, naproxen, and aspirin
  • lansoprazole (Prevacid)
  • sertraline (Zoloft)
  • acarbose (Prandase, Precose)
  • ranitidine (Tritec, Zantac)
  • ticlopidine (Ticlid)
  • proton-pump inhibitors (PPIs)
  • statins
  • beta-blockers
  • selective serotonin-reuptake inhibitors (SSRIs)

Risk factors

Although people of any age can develop collagenous colitis, factors that may increase the risk of developing the condition include:

  • Being over 50. An estimated 75 percent of cases develop in people 50 years of age or older, though some cases in children have been reported.
  • Being female. Women are more likely than men to develop collagenous colitis.
  • Smoking.
  • Some medications. Several gastrointestinal, digestive, sleep, and mood medications have been linked to collagenous colitis.
  • Having an autoimmune condition.
  • Family history. People who have a family history of autoimmune conditions or a type of colitis are more likely to develop collagenous colitis.


A gastroenterologist, or doctor that specializes in digestive and gastrointestinal conditions, will usually diagnose and treat collagenous colitis.

A gastroenterologist may start by performing a physical exam. He will then ask questions about the person’s family and medical history, as well as lifestyle habits, eating patterns, whether they smoke or have smoked, and which medications they use.

To diagnose collagenous colitis, a gastroenterologist will need to take multiple biopsies from different sections of the colon.

A colon biopsy requires either a colonoscopy or a sigmoidoscopy, which involve the insertion of an endoscope into the anus. An endoscope is a plastic tube with a tiny camera that enables the doctor to see inside the intestine.

These tissue samples will be sent to a pathologist, who will analyze the tissue biopsies under a microscope.

Many doctors will use additional medical tests to rule out the presence of other inflammatory gastrointestinal conditions as part of the diagnostic process.

Additional tests include:

  • blood tests
  • stool tests
  • X-rays
  • computerized tomography (CT) scan
  • magnetic resonance imaging (MRI) scan


psyllium dietary fibre supplements in capsule form.
Psyllium husk is a supplement that may help to treat collagenous colitis by adding bulk to stools.

In most cases, collagenous colitis responds well to treatment. And in some cases, the symptoms even resolve without medical intervention.

In the first instance, doctors will advise a person to stop using any medication that is associated with collagenous colitis.

A variety of medications exist that can help reduce or resolve symptoms. Most studies have found that budesonide is an effective first line of therapy for collagenous colitis.

Other common medications prescribed to help treat collagenous colitis include:

  • antidiarrheal medications, commonly those containing bismuth subsalicylate, diphenoxylate, or loperamide,
  • supplements to increase the bulk of stool, such as psyllium (Metamucil)
  • cholestyramine
  • mesalamine
  • antibiotics

If symptoms do not improve, doctors may prescribe:

  • anti-TNF therapies, which block part of the immune response
  • immunomodulators

Making a few lifestyle choices can usually also help reduce symptoms. These include:

In rare cases, usually where severe symptoms have not responded to other forms of treatment, a doctor may recommend surgery to treat collagenous colitis.

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Though each case of collagenous colitis varies, certain foods and chemicals are thought to increase the severity of symptoms and even spark flare-ups.

Although there is much conflicting information about what a person with collagenous colitis should and should not eat, the following dietary changes may help with easing symptoms and reducing the risk of complications:

  • avoiding caffeine and artificial sugars
  • avoiding dairy products if the person is lactose intolerant
  • avoiding foods containing gluten

It is essential to drink plenty of liquids, and this is particularly important when someone has diarrhea.

People with collagenous colitis should speak to a doctor or dietitian to work out what the best approach to take with diet would be.


Collagenous colitis is a type of microscopic colitis that causes periods of watery, non-bloody diarrhea that can last for days to months.

It is different from other forms of inflammatory bowel disease (IBD) because the colon appears normal on a colonoscopy and only shows signs of inflammation under the microscope. It is marked by a thick layer of collagen under the colon lining.

Symptoms are usually intermittent, meaning that most people experience flare-ups for a period followed by a period without symptoms.

The symptoms of collagenous colitis can be uncomfortable and may lead to dehydration and malnutrition. However, symptoms can be managed with medications and diet adjustments.

Unlike other types of inflammatory gastrointestinal conditions, collagenous colitis is not thought to increase the risk of colon cancer.

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