Microscopic colitis

Overview

Microscopic colitis is a condition that causes chronic, watery diarrhea. It gets its name because the inflammation in the lining of the colon can only be seen under a microscope—it looks normal during a standard colonoscopy. This is a different condition from ulcerative colitis or Crohn's disease, which are types of inflammatory bowel disease.

Microscopic colitis is not as common as other bowel conditions, but it is being diagnosed more often as doctors become more aware of it. It is considered a relatively rare condition.

It most often affects people over 50, and women are about twice as likely to develop it as men. People with certain autoimmune diseases, like celiac disease, are also at higher risk.

Symptoms

Common symptoms

• Chronic, watery diarrhea that may come and go
• Urgent need to have a bowel movement
• Abdominal cramps or pain
• Feeling of incomplete emptying after a bowel movement
• Weight loss from losing fluids
• Nausea

Symptoms in children

• Microscopic colitis is rare in children, but when it occurs, symptoms are similar to adults—mainly watery diarrhea. Young children may also show signs of poor weight gain or failure to thrive.

Symptoms in older adults

• Older adults with microscopic colitis are at a higher risk of dehydration and electrolyte imbalances due to fluid loss. They may also have more fatigue and weakness, and symptoms can be harder to manage if they have other health conditions.

Causes

Main causes

• The exact cause of microscopic colitis is not fully understood. It involves inflammation of the colon lining, which is likely triggered by an abnormal immune response.

Risk factors

• Having another autoimmune condition, such as celiac disease, rheumatoid arthritis, or thyroid disease
• Taking certain medications, including non-steroidal anti-inflammatory drugs (NSAIDs), proton pump inhibitors (PPIs), and some antidepressants
• Smoking cigarettes
• Being over the age of 50
• Being female

When to see a doctor

See a doctor urgently if:

• If you have severe diarrhea with signs of dehydration (dizziness, dry mouth, dark urine)
• If you have severe abdominal pain that is not relieved by over-the-counter remedies
• If you have blood in your stool (though this is not typical for microscopic colitis, it should always be checked)

Book a routine appointment if:

• If you have had watery diarrhea for more than a few weeks and it is affecting your daily life
• If you have diarrhea that wakes you up at night
• If you have unintentional weight loss

Diagnosis

Microscopic colitis is diagnosed with a colonoscopy—a test where a thin tube with a camera is passed into your colon. The colon may look normal, so your doctor will take small tissue samples (biopsies) from different parts of the colon. These samples are then examined under a microscope to look for the specific signs of inflammation.

Tests that may be done

• Colonoscopy with biopsy (the main test)
• Stool tests to rule out infections and other causes of diarrhea
• Blood tests to check for dehydration, anemia, or celiac disease

What to expect at your appointment

The colonoscopy is usually done as a day procedure. You will be given a laxative to clean out your colon beforehand, and you may be sedated during the test. The biopsies are painless. Results from the microscope analysis usually take a week or two. You will not feel anything different after the test, though you may have some mild bloating.

Treatment

Treatment for microscopic colitis focuses on relieving diarrhea and reducing inflammation. Many people improve by making dietary changes and stopping certain medications. If symptoms persist, your doctor may recommend medications to reduce inflammation and slow down bowel movements. The goal is to control symptoms so you can live normally.

Self-care at home

• Drink plenty of clear fluids to prevent dehydration (water, clear broths, oral rehydration solutions)
• Avoid caffeine, alcohol, and spicy foods if they make your symptoms worse
• Eat smaller, more frequent meals instead of large portions
• Consider a low-fat, low-fiber diet during flare-ups—some people find that reducing fiber helps

Medical treatments

If self-care is not enough, your doctor may recommend medications to stop diarrhea, such as over-the-counter anti-diarrheal medicines. For more persistent symptoms, prescription medications that reduce inflammation in the colon (such as a type of steroid that works mainly in the gut) or that calm the immune system may be used. In some cases, your doctor may suggest trying a medication that contains bismuth. Treatment is tailored to each person, and your healthcare provider will discuss the options that are right for you.

When is surgery considered?

Surgery is rarely needed for microscopic colitis. Only in very severe cases that do not respond to any medical treatment might a surgeon consider removing part of the colon (colectomy). This is exceptionally rare.

Living with this condition

Living with microscopic colitis means planning ahead for bathroom breaks, especially when you are out. It can be helpful to know where public restrooms are and to carry a 'go bag' with extra underwear, wipes, and a change of clothes. Keeping a food and symptom diary can help you identify triggers.

Lifestyle tips

• Quit smoking, as it can worsen symptoms
• Manage stress with relaxation techniques like deep breathing, meditation, or gentle exercise
• Get enough sleep to support your immune system

Diet and exercise

During flare-ups, a low-fiber, low-fat diet may be easier on your gut. Avoid high-fiber foods like whole grains, nuts, and raw vegetables when symptoms are active. As you feel better, you can gradually add these back. Gentle exercise like walking or yoga can help reduce stress and improve overall well-being.

Mental health and emotional wellbeing

Constant diarrhea can cause anxiety, embarrassment, and social isolation. It is normal to feel frustrated or worried about not being able to control your bowels. Talking to a counselor or support group can help you cope with these feelings.

Prevention

Microscopic colitis cannot always be prevented because the exact cause is not fully understood. However, you may lower your risk by avoiding unnecessary use of medications linked to the condition (like NSAIDs and PPIs) and by not smoking. If you have an autoimmune condition, managing it well may also help.

Complications

If left untreated

• Dehydration and electrolyte imbalances (which can be serious, especially in older adults)
• Weight loss and malnutrition
• Fatigue and weakness from ongoing fluid loss

Long-term outlook

The outlook for microscopic colitis is very good. Most people respond well to treatment and can control their symptoms. It is not a life-threatening condition, and it rarely leads to serious complications if managed properly. With the right care, the majority of people can return to a normal life.

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