Microscopic Colitis: Understanding Chronic Diarrhea and Why Budesonide Is the First-Line Treatment

Chronic diarrhea that won’t go away-no blood, no fever, no obvious cause-can be one of the most frustrating health problems out there. You’ve tried diet changes, probiotics, antidiarrheals, and still, you’re running to the bathroom 6, 8, even 10 times a day. If this sounds familiar, you might be dealing with microscopic colitis. It’s not Crohn’s disease. It’s not ulcerative colitis. And unless a doctor takes a biopsy, your colon looks perfectly normal on a colonoscopy. That’s why it’s called microscopic colitis. The inflammation hides under the microscope.

What Exactly Is Microscopic Colitis?

Microscopic colitis is a type of inflammatory bowel disease that causes chronic, watery diarrhea without visible damage to the colon lining. It was first identified in 1984, and today, we know it comes in two forms: collagenous colitis and lymphocytic colitis. Both share the same symptoms but differ in what the biopsy shows under the microscope.

In lymphocytic colitis, there’s an abnormal buildup of white blood cells (lymphocytes) inside the colon lining-more than 20 per 100 surface cells. In collagenous colitis, a thick band of collagen, at least 10 micrometers wide, forms just beneath the lining. Neither shows up on a colonoscopy. You need a biopsy, usually taken from multiple areas of the colon, to confirm the diagnosis.

It mostly affects people over 50, and women are two to three times more likely to get it than men. The average time from first symptom to diagnosis? About 11 months. Many patients see multiple doctors before someone thinks to check for this condition.

What Are the Symptoms?

The hallmark is chronic, non-bloody, watery diarrhea. You won’t see blood in the stool, which is why many assume it’s just a virus or food intolerance. But this isn’t temporary. It lasts for weeks, months, or even years. People often report:

• 5 to 10 bowel movements a day
• Urgency-sometimes with incontinence
• Abdominal cramping or bloating (in 40-60% of cases)
• Nocturnal diarrhea (waking up at night to go)
• Weight loss, especially in collagenous colitis

Many patients describe their lives as being on hold. They avoid travel, social events, even work, because they can’t predict when the next episode will hit. The condition often follows a relapsing pattern: you feel better for a while, then it comes back without warning.

Why Is Budesonide the Go-To Treatment?

Before budesonide, treatment options were hit or miss. Anti-diarrheals like loperamide helped a little. Bismuth subsalicylate (Pepto-Bismol) worked for some, but only about 26% of patients saw full relief. Mesalamine? Around 40-50% response. Cholestyramine helped if bile acid malabsorption was the issue-but not everyone has that.

Then came budesonide. It’s not your typical steroid like prednisone. It’s designed to work locally in the gut. About 90% of it gets broken down by the liver before it ever reaches your bloodstream. That means it shuts down inflammation in the colon without causing the same side effects as older steroids.

Multiple clinical trials show budesonide 9 mg daily for 6-8 weeks leads to clinical remission in 75-85% of patients. In one major study, 84% of collagenous colitis patients had their diarrhea completely stop after 8 weeks on budesonide, compared to just 38% on placebo. Most people start feeling better within 10-14 days.

How Does Budesonide Compare to Other Treatments?

Here’s how budesonide stacks up:

Comparison of Treatments for Microscopic Colitis

Treatment	Remission Rate	Side Effects	Duration of Use
Budesonide (9 mg/day)	75-85%	Mild: insomnia, acne, headache	6-8 weeks (induction); maintenance possible
Prednisone	75-80%	High: weight gain, bone loss, high blood sugar, mood swings	Not recommended long-term
Bismuth subsalicylate	26%	Black stools, occasional nausea	Long-term use safe
Mesalamine	40-50%	Mild: gas, headache	Often used as add-on
Cholestyramine	60-70% (if bile acid issue)	Constipation, bloating	Long-term use common
Anti-TNF (e.g., infliximab)	20-30%	High: infection risk, $2,500-$3,000 per infusion	Only for refractory cases

Budesonide wins because it’s effective, fast-acting, and safe enough for short-term use. Prednisone works just as well-but at the cost of serious side effects, especially in older adults. Anti-TNF drugs like infliximab are too expensive and risky for most people with microscopic colitis. That’s why budesonide is the first-line treatment in 90% of European and 85% of North American guidelines.

What About Relapse and Long-Term Use?

Here’s the catch: about half of patients relapse within a year after stopping budesonide. That’s why many need maintenance therapy-lower doses taken long-term. Doctors often reduce the dose to 6 mg or even 3 mg daily after the initial 8 weeks, depending on how the patient responds.

Some patients stay on low-dose budesonide for years. Studies show this keeps symptoms under control, but there are open questions. Can long-term, low-dose use affect adrenal function in older people? Is bone density monitoring necessary? Yes, especially if you’re over 50 and on steroids for more than 3 months. Doctors recommend checking bone density, blood sugar, and blood pressure before and during treatment.

Cost is another issue. Generic budesonide costs $150-$250 for an 8-week course. The brand version, Entocort EC, runs $800-$1,200. Without insurance, many patients can’t afford it. Some turn to bismuth or cholestyramine as cheaper alternatives-even though they’re less effective.

Real Patient Stories

On patient forums, the stories are mixed but mostly hopeful. One user on Reddit wrote: “Went from 10 bathroom trips a day to 2 within 10 days. I cried the first time I made it through a movie without running to the bathroom.” Another said: “It worked great for 6 weeks. Then my symptoms came back. Now I’m on maintenance for two years. I hate being on steroids, but I hate the diarrhea more.”

Side effects are usually mild-insomnia, acne, mood changes-but they’re real. About 15% report trouble sleeping. A few report weight gain or increased appetite. These aren’t the dramatic side effects of prednisone, but they’re enough to make some patients stop.

Many find success combining treatments. One patient said: “Budesonide fixed the inflammation, but I still had diarrhea. My doctor added cholestyramine. That was the missing piece. I’ve been symptom-free for 18 months.”

What’s Next for Treatment?

The future is looking promising. In 2023, the FDA gave Fast Track status to vedolizumab-a biologic drug already used for Crohn’s-for treating refractory microscopic colitis. Early trials show 65% of patients go into remission after 14 weeks. That’s huge for people who don’t respond to budesonide.

Researchers are also looking at genetic markers. Early data suggests people with HLA-DQ2 or HLA-DQ8 genes respond better to budesonide. That could mean future testing to predict who will benefit most.

The European Microscopic Colitis Group is also updating guidelines to include fecal calprotectin-a simple stool test-as a way to monitor treatment without repeated biopsies. That’s a big win for patients.

What Should You Do If You Suspect Microscopic Colitis?

If you’ve had chronic watery diarrhea for more than 4 weeks-with no blood, no fever, and no clear trigger-talk to your doctor about microscopic colitis. Ask for a colonoscopy with multiple biopsies. Don’t assume it’s IBS. Don’t wait for it to go away on its own.

If diagnosed, budesonide is your best bet for quick relief. Take it exactly as prescribed. Don’t stop early, even if you feel better. And don’t panic if you need to stay on a low dose for months. For many, it’s the difference between living normally and being trapped by bathroom anxiety.

It’s not a cure. But for now, it’s the most effective tool we have. And for thousands of people who spent years searching for answers, that’s enough.