Microscopic Colitis
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Medically reviewed by Kumkum Sarkar Patel, MD
Microscopic colitis is an inflammatory bowel disease (IBD) that causes chronic inflammation in the inner lining of the colon, leading to persistent, watery diarrhea. The inflammation can't be seen during an imaging procedure like a colonoscopy—it can only be seen by looking at a sample of colon tissue under a microscope.
The exact cause of microscopic colitis is not fully understood. Evidence suggests a combination of factors contributes to an abnormal immune response that leads to inflammation in the colon.
About 700,000 people in the United States have microscopic colitis. It is most common in older adults and people with autoimmune disorders like celiac disease.
There is no cure for microscopic colitis, but most people can manage the condition with medications and lifestyle modifications.
Types
There are two types of microscopic colitis: lymphocytic and collagenous. Healthcare providers determine which type of microscopic colitis you have by viewing your colon tissue under a microscope. The two types cause different changes to the colon tissue, but they have identical symptoms and treatments.
Lymphocytic Colitis
With lymphocytic colitis, the colon lining (mucosa) contains high numbers of lymphocytes (white blood cells)—20 or more for every 100 cells. In healthy colon mucosa, there are typically fewer than five lymphocytes for every 100 cells. The collagen layer under the colon mucosa is also sometimes slightly thicker than normal in people with this form of microscopic colitis.
Collagenous Colitis
With collagenous colitis, the collagen layer beneath the colon's lining is thicker than normal, measuring more than 10 micrometers in diameter. In healthy colon tissue, this collagen is usually 3-4 micrometers in diameter. Some people with collagenous colitis also have slightly elevated lymphocyte counts in the colon mucosa.
Microscopic Colitis Symptoms
Microscopic colitis symptoms typically develop gradually, though up to 40% of people with the condition experience a sudden onset of symptoms. Symptoms tend to progress and worsen over time. You may have periods of remission when you have few to no symptoms, followed by flare-ups when symptoms return or worsen.
Chronic watery, non-bloody diarrhea is the most common symptom of microscopic colitis. People with microscopic colitis can experience between three to eight diarrhea episodes daily, though some people may have up to 15 daily bowel movements during flare-ups.
Besides diarrhea, microscopic colitis symptoms can include:
Urgency to have a bowel movement
Fecal incontinence (inability to control bowel movements)
Weight loss
Although less common, some people with microscopic colitis may also experience:
Eye pain, redness, blurry vision, or sensitivity to light
Muscle aches
Headaches or migraine
Mouth sores
Swollen lymph nodes
Nausea and vomiting
Causes
Although the exact cause of microscopic colitis is unknown, research suggests genetics, an imbalance of microorganisms in the gut, and abnormal immune system activity may contribute to its development.
Abnormal Immune Response
Inflammation in the colon's lining may occur due to an abnormal immune response, leading the body's immune system to mistakenly attack colon tissue and cause inflammation.
People with certain autoimmune disorders, diseases where the immune system attacks healthy tissue, may be likelier to have intestinal inflammation. Celiac disease, type 1 diabetes, and rheumatoid arthritis (RA) are autoimmune disorders that have been linked to an increased risk of microscopic colitis.
Genetics
Some evidence suggests that microscopic colitis runs in families. Researchers are investigating possible links between inherited certain genes and the risk of microscopic colitis. One study found a link between a family history of Crohn's disease and an increased risk of microscopic colitis, but more research is needed to determine what role genetics play in the development of the condition.
Gut Microbiome Imbalance
The gut microbiome is a diverse community of bacteria and other microorganisms living in the gastrointestinal (GI) tract. A balanced and diverse gut microbiome is important for maintaining good digestive health. Some research suggests that factors that cause disruptions or imbalances in the gut microbiome, such as previous infections or certain medications, may play a role in the development of microscopic colitis.
Risk Factors
Microscopic colitis can affect anyone, but certain factors can increase your risk, including:
Age: Microscopic colitis is more common in older adults 60 or older.
Sex: Women have higher rates of microscopic colitis than men.
Certain medications: Some medicines are associated with an increased risk of microscopic colitis, including nonsteroidal anti-inflammatory drugs (NSAIDs), proton pump inhibitors, selective serotonin reuptake inhibitors, or SSRIs (antidepressants), hormone replacement therapy (HRT), oral contraceptives, beta-blockers, and statins.
Underlying conditions: People with certain autoimmune conditions, including celiac disease, diabetes, thyroid disorders, and rheumatoid arthritis, are more likely to develop microscopic colitis.
Smoking: Tobacco use increases the risk of microscopic colitis.
Diagnosis
The diagnosis process will likely start with a healthcare provider asking about your symptoms, including how long you've had them and how severe they are. They'll also likely ask about your medical history, including whether you have an autoimmune condition and your family's health history. They may also ask about your medication use and other risk factors, such as whether you smoke.
The provider might try to rule out infections or other causes of chronic diarrhea by ordering stool and blood tests.
The healthcare provider will order a colonoscopy if they suspect microscopic colitis, A colonoscopy with biopsy is the only way to definitively diagnose microscopic colitis. During a colonoscopy, the gastroenterologist (a doctor who specializes in treating and managing digestive disorders) will insert a thin, flexible tube with a light and camera on the end through your anus and into your colon to view the colon lining.
Inflammation from microscopic colitis cannot be seen on camera, so they will take biopsies (small tissue samples) from the colon lining and send them to the laboratory for examination under a microscope. When evaluating the sample at a microscopic level, signs of microscopic colitis like elevated white blood cells and thickened collagen band can be detected.
Treatments for Microscopic Colitis
The primary goal of treatment for microscopic colitis is to reduce inflammation so that the frequency and severity of your symptoms improve. Ultimately you'll want to achieve remission, meaning inflammation is well-controlled and not causing symptoms.
There is no cure for microscopic colitis, but medications and lifestyle modifications can help reduce inflammation and control symptoms.
Medications
Healthcare providers prescribe medications to manage symptoms and reduce inflammation in the colon's lining. Depending on the severity of your symptoms, your healthcare provider may prescribe the following:
Bulk-forming agents: Metamucil (psyllium) and other bulk-forming agents can help hold water in the intestines to help bulk up watery diarrhea.
Antidiarrheals: These medicines control diarrhea by slowing the muscle contractions that move bowel contents. Antidiarrheals include Imodium (loperamide), Pepto Bismol (bismuth subsalicylate), and Lomotil (diphenoxylate).
Corticosteroids: Entocort (budesonide) is an oral corticosteroid that reduces inflammation in the colon. Most providers prescribe this for short-term use (around eight weeks)—long enough for many people with microscopic colitis to achieve remission. If symptoms return after that, your healthcare provider may prescribe a lower dose for long-term use.
Bile acid binders: Some people with microscopic colitis may experience a build-up of bile in the intestines, leading to diarrhea. Bile acid binders, such as cholestyramine (sold under brand names like Prevalite and Questran Light), can help reduce this buildup.
Lifestyle Modifications
Lifestyle and dietary changes can help manage microscopic colitis and reduce symptom frequency and severity. These modifications may include:
Changing medication: If you take medications associated with microscopic colitis flares, your healthcare provider may switch you to an alternate medication.
Avoiding smoking: Smoking can trigger or worsen intestinal inflammation. Talk to your healthcare provider about smoking cessation programs if you smoke and are ready to quit.
Avoiding trigger foods: Caffeine, alcohol, and artificial sweeteners can worsen microscopic colitis symptoms. Avoid any other foods you might be sensitive to. For instance, if you are lactose intolerant, your healthcare provider may ask you to avoid dairy. They may ask you to avoid gluten if you have celiac disease or gluten intolerance.
Staying hydrated: When you have chronic diarrhea, your body loses fluids and electrolytes. If you lose more fluids than you replace, you can become dehydrated. Drink plenty of fluids throughout the day to prevent dehydration.
How To Prevent Microscopic Colitis
There is no known way to prevent microscopic colitis. However, making dietary changes may help reduce disease flare-ups and promote remission. Keeping a food diary can help identify foods and beverages that trigger or worsen your symptoms so you can limit your intake or avoid them.
Talk to your healthcare provider or a registered dietician before changing your diet. They may recommend a specific diet based on your symptoms and trigger foods. Along with avoiding trigger foods, tips that may help reduce symptoms include:
Eat small, frequent meals throughout the day rather than three large meals
Reduce your intake of greasy, fried foods
Limit high-fiber foods, such as nuts, seeds, popcorn, and leafy greens
Avoid caffeine like coffee, tea, and sodas
Limit your intake of dairy products if you are lactose intolerant
Related Conditions
People with microscopic colitis have higher rates of autoimmune and allergic disorders than people who do not have microscopic colitis. Research suggests that shared genetic and environmental factors play a role in developing these related conditions.
Conditions you might be more likely to have if you have microscopic colitis include:
Celiac disease: Many people with microscopic colitis have celiac disease, an autoimmune disorder that causes gluten intolerance. With celiac disease, consuming gluten triggers an overactive immune response that causes damage to the small intestine.
Thyroid disease: Thyroid disorders cause the thyroid (a butterfly-shaped gland in the throat) to produce too little or too much thyroid hormone.
Type 1 diabetes: Research shows that type 1 diabetes is 80% more common in people with microscopic colitis than the general population. Type 1 diabetes is an autoimmune disorder that causes the body to attack the pancreas, leading to insufficient insulin production.
Rheumatoid arthritis (RA): People with microscopic colitis have double the risk of rheumatoid arthritis than the general population. Rheumatoid arthritis is an autoimmune disease that causes the immune system to attack the joints.
Allergies: A small study found that 26% of people with microscopic colitis had allergic disorders like allergic rhinitis and that 22% of people with this digestive condition had allergies to certain foods.
Living With Microscopic Colitis
Microscopic colitis can be a frustrating condition—the uncertainty of when symptoms will develop and their effects can significantly affect your quality of life. However, many people with microscopic colitis achieve remission in just weeks or months by following their treatment plan and making lifestyle adjustments. If the disease flares again, you can take measures to bring it back into remission.
Microscopic colitis does not appear to impact life expectancy. Unlike other types of IBD, such as Crohn's disease and ulcerative colitis, microscopic colitis is not associated with an increased risk of colon cancer.
Talk to your healthcare provider if you have symptoms of microscopic colitis or if you have a diagnosis and your symptoms are worsening despite treatment. Your healthcare provider will work with you to find an effective treatment plan.
Frequently Asked Questions
At what age do people get microscopic colitis?
Microscopic colitis can affect people of all ages, but most people are diagnosed between the ages of 60-65.
What foods trigger microscopic colitis?
Trigger foods for microscopic colitis can vary person to person. However, common trigger foods include caffeine, alcohol, dairy, artificial sweeteners, and gluten.
Do probiotics help microscopic colitis?
Some evidence suggests that certain probiotics containing Boswellia serrata bacteria strains may benefit people with microscopic colitis. However, the American Gastrointestinal Association (AGA) does not recommend probiotics for managing microscopic colitis because most research shows they are ineffective in improving symptoms.
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