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Microscopic colitis: the signs, the tests, treatment, and day to day
For adults who have had watery diarrhea for weeks, who were just told they have microscopic colitis, who wonder whether a medicine is causing it, or who have a colonoscopy coming up; and for the people who love them. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK, part of the NIH) says microscopic colitis is a chronic inflammatory bowel disease in which abnormal reactions of the immune system cause inflammation of the inner lining of your colon; that doctors can only see it by looking at colon tissue under a microscope; and that, unlike other kinds of inflammatory bowel disease, it does not increase your risk of colon cancer. This page passes on, by name, what NIDDK says: the signs, and remission and relapse; the two types, who is more likely, and the medicines and smoking linked to it; blood and stool tests, a colonoscopy and biopsies; the kinds of medicine, and rarely surgery; and food and drink. It builds the words to say to a doctor, and prints a card for your medicine changes and flares.
Right now
- Fainting or confusion, a lot of blood from the rectum, or severe belly pain with a hard, swollen belly? Call 911 (ours). Do not drive yourself.
- Very thirsty, making little or dark urine, or dizzy when you stand up? Those can be signs of dehydration: see a doctor the same day (ours). NIDDK says severe diarrhea may lead to dehydration.
- Wondering whether one of your medicines is the cause? Do not stop a prescribed medicine on your own; ask your doctor (ours). NIDDK says your doctor may recommend changing it.
- It is all too much, or you are thinking of ending your life? Call or text 988, any hour (ours).
More help
- Other kinds of bowel disease, on this site: Ulcerative colitis · Crohn’s disease · Celiac disease · Lactose intolerance · An upset stomach: find the right page.
- Accidents and the colonoscopy: Bowel control problems · Colon polyps and colonoscopy.
- Lowering your risk: When you want to quit smoking.
- Day to day: My medicines list · Symptom diary · Get ready for your appointment.
- Care and costs: When you need a doctor and can’t pay · When a medical bill is too much.
- In a crisis: Help right now (988, 911). All our free tools.
An upset stomach, and not sure this is the right page? The pages on this site for throwing up, diarrhea, heartburn and constipation, on one list.
This page and its wording were written with AI (Claude) for Scarlet Beast (our AI policy). No doctor or nurse has reviewed it. The facts were read on October 17, 2026 on NIDDK’s Microscopic Colitis pages (NIH): the overview, Definition & Facts, Symptoms & Causes, Diagnosis, Treatment and Eating, Diet, & Nutrition, all last reviewed in April 2021. NIDDK has no Spanish version of these pages; our Spanish page is our own translation. NIDDK names kinds of medicine (and one steroid by name); we name no single medicine or brand. Ours: 911 for fainting or confusion, a lot of blood from the rectum, or severe belly pain with a hard, swollen belly; a doctor the same day for signs of dehydration; seeing a doctor for weeks of diarrhea or any blood; never stopping a prescribed medicine on your own; asking whether biopsies were taken; the quitline numbers (as on our quit-smoking page); the colitis card; 988 when it is too much; health centers when money is tight; and the order of the steps. What we left out: medicine names, doses, research studies, and clinical pages for providers. This page saves nothing and loads no trackers.