Colitis occurs when your colon, or large intestine, is inflamed.

Microscopic colitis is a type of colitis that’s best identified by looking at colon cells under a microscope. The main subtypes of microscopic colitis are collagenous colitis and lymphocytic colitis.

In collagenous colitis, a thick layer of collagen — a type of connective protein — forms within the colon tissue. Its symptoms can disappear and reappear.

Lymphocytic colitis occurs when the colon contains a large number of lymphocytes, which are types of white blood cells. Learn more about it and other forms of colitis.

The symptoms of collagenous colitis can come and go, and vary in severity.

The most common symptoms include:

Less common symptoms include:

Like many other gastrointestinal conditions, the exact cause of collagenous colitis is unknown. Research indicates that it likely has a genetic basis and could be related to autoimmune conditions.

Some possible causes of collagenous colitis include:

Collagenous colitis isn’t contagious. It can’t spread to other people.

Medications as triggers

Medications that may trigger microscopic colitis and collagenous colitis include:

Research is mixed on the effects of the following medications:

Some research states that they have little to no effect on microscopic colitis, or may even be associated with lower rates of the condition.

Other studies indicate that these medications also trigger microscopic colitis and collagenous colitis.

According to a 2021 study, if these medications are associated with increased rates of microscopic colitis and collagenous colitis, it may be because they make diarrhea worse. A worsening case of diarrhea then prompts a doctor to make a diagnosis of colitis.

Collagenous colitis is more common among women than men. It’s also more common among people who are over 50 years old.

In addition, people who have celiac disease are more likely to have collagenous colitis.

Collagenous colitis may also be more common among people who currently smoke and people with a family history of the condition.

Researchers have noticed that the number of collagenous colitis cases is increasing. This may be because better detection is available and there’s increased awareness of the condition.

Collagenous colitis can only be diagnosed with a biopsy of the colon. You’ll likely also have a colonoscopy or sigmoidoscopy so that the doctor can better evaluate the health of your colon.

During the biopsy, a healthcare professional removes several small pieces of tissue from your colon. Then the tissues are examined under a microscope.

The common diagnostic process includes:

  • a medical history
  • colonoscopy with a biopsy
  • lab tests, such as blood and stool tests
  • imaging tests, such as CT scans, MRIs, or X-rays
  • endoscopy

Some tests and procedures are used to rule out other medical conditions that may cause similar symptoms, such as irritable bowel syndrome (IBS) and the infection Clostridium difficile (C. diff).

In some cases, collagenous colitis disappears on its own. However, some people need treatment.

Your treatment plan will depend on the severity of your symptoms.

Diet and lifestyle changes

Your doctor may recommend diet and lifestyle changes to help treat this condition. These changes are usually the first part of any treatment plan.

Common diet changes include:

Common lifestyle changes include:


Your doctor will review the medications you currently take and make suggestions about either continuing or stopping them.

In 2016, the American Gastroenterological Association (AGA) released its guidelines on microscopic colitis. The AGA recommends starting with budesonide, a type of corticosteroid, before considering other medications.

Other medications your doctor may recommend to help treat the symptoms of collagenous colitis include:

The supplement psyllium may be recommended, too. Immunomodulators or anti-TNF (tumor necrosis factor) therapies may be used in extreme cases.

The Food and Drug Administration (FDA) hasn’t approved any medications for microscopic colitis or collagenous colitis. However, medications such as mesalamine and sulfasalazine are FDA approved for the treatment of ulcerative colitis.

If a doctor prescribes medications such as these for collagenous colitis, it’s considered an example of off-label drug use.


Off-label drug use means a drug that’s approved by the FDA for one purpose is used for a different purpose that hasn’t yet been approved.

However, a doctor can still use the drug for that purpose. This is because the FDA regulates the testing and approval of drugs, but not how doctors use drugs to treat their patients. So your doctor can prescribe a drug however they think is best for your care.


Your doctor may recommend surgery if diet and medication changes don’t help. Surgery is usually reserved for extreme cases. It’s not a typical treatment for collagenous colitis.

The most common types of surgery for collagenous colitis include:

  • colectomy, which means removing all or part of the colon
  • ileostomy, which means creating an opening in the abdomen after a colectomy

Collagenous colitis doesn’t cause blood in your stool, increase your risk of colon cancer, or have any effect on life expectancy. Symptoms may affect a person’s quality of life, but they’re not life threatening and won’t typically require emergency medical care.

However, it’s worth seeing a doctor if you have chronic watery diarrhea in combination with any of the common risk factors for collagenous colitis.

You’ll also want to see a doctor if you’re diagnosed with collagenous colitis and your recommended treatment plan doesn’t help reduce your symptoms.

Collagenous colitis can come and go, and relapses are common. You may need to try several treatments to find relief from the symptoms.

The time it takes to recover can vary. Some people may have symptoms for weeks, months, or years.

There are no current recommendations for preventing collagenous colitis. However, following the diet and medication changes recommended by your doctor may reduce your likelihood of having a relapse.

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