ConditionDigestive system
Microscopic Colitis
Microscopic colitis is inflammation of the colon that causes chronic, watery, non-bloody diarrhea, often with urgency and nighttime bowel movements. The colon looks normal during colonoscopy; the inflammation is only visible when biopsies are examined under a microscope. It is most common in women over 50. Common medicines such as NSAIDs, proton pump inhibitors and SSRIs can trigger it. Stopping triggers and taking budesonide controls symptoms in most people.
Also called: Collagenous colitis, lymphocytic colitis
At a glance
- What it is
- Colon inflammation seen only on biopsy, causing chronic watery diarrhea.
- Types
- Collagenous colitis (thickened collagen band) and lymphocytic colitis (more lymphocytes in the lining).
- Who
- Mostly people over 50, more often women; often with autoimmune conditions.
- Triggers
- NSAIDs, PPIs, SSRIs, statins and other medicines; smoking.
- Treatment
- Stop triggers; budesonide is the most effective medicine; loperamide for mild cases.
When to get help
Call 911 or go to the ER
- Signs of severe dehydration: dizziness on standing, fainting, confusion, very little urine
See a doctor within a day or two
- Diarrhea with blood, fever or severe abdominal pain (not typical of microscopic colitis)
- More than 6 to 10 watery stools a day with weakness
Book a routine appointment
- Watery diarrhea lasting more than 4 weeks, especially after age 50
- Nighttime diarrhea, urgency or accidents
- Weight loss with chronic diarrhea
- Diarrhea that started after a new medicine
What microscopic colitis is
Microscopic colitis is a type of inflammatory bowel condition, but it differs from Crohn's disease and ulcerative colitis. The colon lining looks normal or nearly normal on colonoscopy, and it does not cause ulcers, bleeding or strictures. Biopsies show one of two patterns:
| Type | What the biopsy shows |
|---|---|
| Collagenous colitis | A thickened band of collagen under the lining, plus inflammation |
| Lymphocytic colitis | Increased lymphocytes (white blood cells) in the lining, normal collagen band |
The two types have the same symptoms and treatment.
Symptoms
- chronic, watery, non-bloody diarrhea, often 4 to 10 times a day
- urgency and fecal incontinence
- nighttime diarrhea
- abdominal pain or cramping
- fatigue
- weight loss
- dehydration in severe cases
Symptoms may start suddenly, like an infection, or gradually, and often come and go over months to years.
Causes and risk factors
The cause is not fully understood. It likely involves an abnormal immune response in the colon to triggers in susceptible people.
Medicines linked to microscopic colitis
- NSAIDs (ibuprofen, naproxen, aspirin)
- proton pump inhibitors (omeprazole, lansoprazole)
- SSRIs (sertraline and others)
- statins
- beta-blockers, ACE inhibitors and some others
Other risk factors
- age over 50
- female sex
- smoking
- autoimmune conditions: celiac disease, autoimmune thyroid disease, rheumatoid arthritis, type 1 diabetes
Microscopic colitis vs IBS vs IBD
| Microscopic colitis | IBS | Ulcerative colitis | |
|---|---|---|---|
| Typical age | Over 50 | Under 50 at onset | Any, often 15 to 40 |
| Stool | Watery, no blood | Loose or hard, varies | Often bloody |
| Night symptoms | Common | Rare | Common |
| Colonoscopy | Normal | Normal | Inflamed, ulcerated |
| Biopsy | Abnormal | Normal | Abnormal |
Because it can mimic IBS with diarrhea, biopsies are recommended during colonoscopy for people with chronic watery diarrhea.
Diagnosis
- colonoscopy with multiple biopsies from different parts of the colon: the key test
- stool tests to exclude infections
- blood tests: celiac antibodies (celiac disease often coexists), thyroid function, blood count
- medicine review for potential triggers
Treatment
Remove triggers
- stop or switch medicines linked to the condition, with your doctor's guidance
- stop smoking
- reduce caffeine, alcohol and dairy if they worsen symptoms
Medicines
- budesonide: a steroid that acts mainly in the gut with fewer side effects than other steroids. It is the most effective treatment, leading to remission in most people within weeks. Some need low-dose maintenance.
- loperamide for mild symptoms (follow the label dose)
- bismuth subsalicylate for mild cases
- bile acid binders (cholestyramine) if bile acid diarrhea is also present
- immunomodulators or biologics (anti-TNF drugs, vedolizumab) for rare resistant cases
Diet
No specific diet cures microscopic colitis, but during flares many people feel better with:
- smaller, more frequent meals
- fewer high-fat, spicy, dairy, caffeinated and sugar-alcohol foods
- plenty of fluids, including oral rehydration solution if diarrhea is heavy
- a gluten-free diet only if celiac disease is confirmed
Outlook
Microscopic colitis does not increase colorectal cancer risk and does not damage the colon permanently. Symptoms respond well to treatment, though relapse after stopping budesonide is common, and some people need long-term low-dose therapy. Many eventually go into lasting remission.
Frequently asked questions
What are the symptoms of microscopic colitis?
The main symptom is chronic watery diarrhea without blood, often with urgency, nighttime bowel movements and sometimes accidents. Abdominal cramps, fatigue and weight loss can occur. It is most common in people over 50.
What causes microscopic colitis?
The exact cause is unknown. It likely results from an immune reaction in the colon. Triggers include medicines such as NSAIDs, proton pump inhibitors and SSRIs, and smoking. It is linked to autoimmune conditions like celiac disease.
How is microscopic colitis diagnosed?
It is diagnosed by taking biopsies during a colonoscopy. The colon looks normal to the eye, but under the microscope the biopsies show a thickened collagen layer (collagenous colitis) or extra lymphocytes (lymphocytic colitis).
What is the best treatment for microscopic colitis?
Budesonide, a gut-targeted steroid, is the most effective treatment, putting most people into remission within weeks. Stopping trigger medicines and smoking also helps. Mild symptoms may respond to loperamide or bismuth.
Is microscopic colitis serious?
It can be very disruptive, but it is not dangerous in the long term. It does not cause colon cancer or permanent damage, and most people respond well to treatment, though symptoms can return.
Sources
This guide was written from current patient and clinical guidance, including:
- American Gastroenterological Association: Clinical Practice Guidelines on the Medical Management of Microscopic Colitis
- American College of Gastroenterology: Microscopic Colitis
- NIDDK: Microscopic Colitis
- Crohn's and Colitis Foundation: Microscopic Colitis
- European Microscopic Colitis Group: Guidelines