Microscopic Colitis: Inflammatory Bowel Disease Explained

Microscopic colitis is a type of Inflammatory Bowel Disease (IBD) that affects the colon, also known as the large intestine. This condition is characterized by chronic, non-bloody diarrhea and abdominal pain. Despite its debilitating symptoms, microscopic colitis often goes undiagnosed because it requires specific diagnostic tests to identify its presence.

Understanding microscopic colitis requires a comprehensive exploration of its causes, symptoms, diagnosis, treatment, and potential complications. This glossary article aims to provide an in-depth explanation of these aspects, offering a thorough understanding of this complex condition.

Understanding Inflammatory Bowel Disease (IBD)

Inflammatory Bowel Disease (IBD) is a term used to describe disorders that involve chronic inflammation of the digestive tract. The two most common types of IBD are Crohn's disease and ulcerative colitis. However, microscopic colitis also falls under this category, though it is less common.

IBD is characterized by periods of flare-ups, where symptoms are severe, and periods of remission, where symptoms are less severe or absent. The exact cause of IBD is unknown, but it is thought to involve a combination of genetic, environmental, and immune system factors.

Types of IBD

Crohn's disease and ulcerative colitis are the most well-known types of IBD. Crohn's disease can affect any part of the digestive tract from the mouth to the anus, while ulcerative colitis only affects the colon and rectum. Both conditions can cause severe symptoms and complications, including abdominal pain, diarrhea, weight loss, and malnutrition.

Microscopic colitis, on the other hand, only affects the colon. It is called 'microscopic' because the inflammation and changes to the tissue can only be seen under a microscope. There are two types of microscopic colitis: collagenous colitis and lymphocytic colitis. Both types share similar symptoms but have distinct microscopic features.

Causes and Risk Factors of Microscopic Colitis

The exact cause of microscopic colitis is unknown, but it is thought to involve a combination of factors. These may include an overactive immune system response, genetic predisposition, and environmental triggers. Certain medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs) and proton pump inhibitors (PPIs), have also been linked to microscopic colitis.

Microscopic colitis is more common in older adults, particularly women. The risk of developing the condition also increases with age. However, it can occur at any age and in both sexes. Smoking is another risk factor for microscopic colitis, although the exact relationship between smoking and the disease is not fully understood.

Genetic Predisposition

Research suggests that there may be a genetic component to microscopic colitis. Some studies have found that people with a family history of the disease are at a higher risk of developing it. However, more research is needed to identify the specific genes involved and understand how they contribute to the disease process.

It's also worth noting that having a family history of other types of IBD, such as Crohn's disease or ulcerative colitis, may increase the risk of developing microscopic colitis. This suggests that there may be common genetic factors across different types of IBD.

Environmental Triggers

Environmental factors may also play a role in the development of microscopic colitis. For example, some studies have suggested that infection with certain types of bacteria or viruses may trigger the disease. However, more research is needed to confirm these findings and understand how these infections might lead to microscopic colitis.

Other potential environmental triggers include stress and certain dietary factors. Some people with microscopic colitis report that their symptoms worsen during periods of high stress or after consuming certain foods or beverages. However, the relationship between these factors and microscopic colitis is not fully understood, and more research is needed in this area.

Symptoms of Microscopic Colitis

The primary symptom of microscopic colitis is chronic, non-bloody diarrhea. This can range from mild to severe, with some people experiencing up to 20 bowel movements a day. Other symptoms may include abdominal pain, weight loss, nausea, and fatigue.

It's important to note that the severity of symptoms can vary widely from person to person. Some people may have mild symptoms that don't significantly impact their daily life, while others may have severe symptoms that interfere with their ability to work or carry out other daily activities. The symptoms can also fluctuate over time, with periods of remission and flare-ups.


Diarrhea in microscopic colitis is typically watery and non-bloody. It can occur at any time of the day or night, and may be accompanied by an urgent need to have a bowel movement. The frequency of bowel movements can vary widely, from a few times a day to more than 20 times a day in severe cases.

Chronic diarrhea can lead to dehydration, which can cause symptoms such as thirst, dry mouth, fatigue, dizziness, and decreased urine output. It can also lead to electrolyte imbalances, which can cause symptoms such as muscle weakness, irregular heartbeat, and changes in blood pressure.

Abdominal Pain

Abdominal pain is another common symptom of microscopic colitis. The pain is typically located in the lower part of the abdomen and may be described as cramping or aching. The severity and duration of the pain can vary from mild and intermittent to severe and constant.

Abdominal pain in microscopic colitis may be related to inflammation and swelling in the colon. It may also be related to changes in bowel movements, such as increased frequency or urgency. In some cases, the pain may be relieved by having a bowel movement.

Diagnosis of Microscopic Colitis

Diagnosing microscopic colitis can be challenging because its symptoms are similar to those of other digestive disorders. The diagnosis is usually made based on a combination of symptoms, medical history, physical examination, and diagnostic tests.

The most definitive test for microscopic colitis is a colonoscopy with biopsy. During this procedure, a long, flexible tube with a camera on the end (a colonoscope) is used to examine the inside of the colon. Small samples of tissue (biopsies) are taken and examined under a microscope to look for the characteristic changes of microscopic colitis.


A colonoscopy is a procedure that allows a doctor to examine the inside of the colon. It is performed using a colonoscope, which is a long, flexible tube with a light and a camera on the end. The colonoscope is inserted through the anus and advanced through the colon. The camera sends images to a monitor, allowing the doctor to visually inspect the colon for any abnormalities.

During a colonoscopy, the doctor can also take small samples of tissue (biopsies) from the colon. These samples are then examined under a microscope to look for the characteristic changes of microscopic colitis. These changes include inflammation and thickening of the layer of connective tissue (collagen) that lines the colon.

Other Diagnostic Tests

In addition to a colonoscopy, other tests may be used to help diagnose microscopic colitis or rule out other conditions. These may include blood tests, stool tests, and imaging tests.

Blood tests can be used to check for signs of inflammation, anemia, or other abnormalities that may suggest microscopic colitis. Stool tests can be used to check for infections, parasites, or other causes of diarrhea. Imaging tests, such as a CT scan or MRI, can be used to visualize the colon and other parts of the digestive tract.

Treatment of Microscopic Colitis

The treatment of microscopic colitis typically involves medications to reduce inflammation and control symptoms. In some cases, changes to the diet or lifestyle may also be recommended. The goal of treatment is to reduce symptoms, improve quality of life, and prevent complications.

It's important to note that treatment for microscopic colitis is usually ongoing, as the condition is chronic and tends to recur. The treatment plan may need to be adjusted over time based on the person's symptoms and response to treatment.


The first line of treatment for microscopic colitis is usually a type of medication called an anti-inflammatory drug. These drugs work by reducing inflammation in the colon, which can help to control symptoms. The most commonly used anti-inflammatory drugs for microscopic colitis are budesonide and mesalamine.

In some cases, other types of medications may be used to treat microscopic colitis. These may include immunosuppressive drugs, which work by suppressing the immune system to reduce inflammation, and anti-diarrheal drugs, which can help to control diarrhea. The specific medications used will depend on the person's symptoms and response to treatment.

Diet and Lifestyle Changes

In addition to medications, changes to the diet and lifestyle may also be recommended for people with microscopic colitis. These changes can help to manage symptoms and improve quality of life.

Dietary changes may include avoiding foods and beverages that worsen symptoms, such as caffeine, alcohol, and high-fat foods. Increasing the intake of fiber and staying hydrated can also help to manage diarrhea. Lifestyle changes may include regular exercise, stress management techniques, and quitting smoking.

Complications of Microscopic Colitis

While microscopic colitis can be effectively managed with treatment, it can lead to complications if left untreated. These complications can include dehydration, malnutrition, and a decreased quality of life due to chronic symptoms.

It's also worth noting that people with microscopic colitis may be at an increased risk of developing other health conditions, such as osteoporosis and other types of IBD. Therefore, regular medical follow-up and monitoring are important for people with this condition.


Chronic diarrhea, the main symptom of microscopic colitis, can lead to dehydration if not properly managed. Dehydration occurs when the body loses more fluids than it takes in, which can disrupt the balance of minerals in the body and affect its ability to function properly.

Symptoms of dehydration can include thirst, dry mouth, fatigue, dizziness, and decreased urine output. In severe cases, dehydration can lead to serious complications such as kidney damage, seizures, and shock. Therefore, it's important for people with microscopic colitis to stay hydrated, especially during periods of severe diarrhea.


Chronic diarrhea can also lead to malnutrition, as it can interfere with the body's ability to absorb nutrients from food. This can lead to deficiencies in essential vitamins and minerals, which can affect various bodily functions and overall health.

Symptoms of malnutrition can include fatigue, weight loss, weakened immune system, and slow wound healing. In severe cases, malnutrition can lead to complications such as organ damage and increased susceptibility to infections. Therefore, it's important for people with microscopic colitis to eat a balanced diet and may need to take nutritional supplements.

Decreased Quality of Life

Chronic symptoms of microscopic colitis, such as diarrhea and abdominal pain, can significantly impact a person's quality of life. These symptoms can interfere with daily activities, work, social interactions, and overall well-being.

Therefore, effective management of symptoms is crucial for improving quality of life in people with microscopic colitis. This can include medications, dietary changes, lifestyle modifications, and psychological support.


Microscopic colitis is a complex condition that requires a comprehensive understanding of its causes, symptoms, diagnosis, treatment, and potential complications. Despite its challenges, effective management of the condition can help to control symptoms, prevent complications, and improve quality of life.

It's important for people with microscopic colitis to work closely with their healthcare provider to develop a personalized treatment plan and to regularly monitor their condition. With proper management, people with microscopic colitis can lead fulfilling and active lives.

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