Symptoms & Causes of Microscopic Colitis
What are the symptoms of microscopic colitis?
Symptoms of microscopic colitis may include
- chronic, watery, nonbloody diarrhea, which is the most common symptom
- diarrhea that occurs at night
- pain in the abdomen
- an urgent need to have a bowel movement
- fecal incontinence
- weight loss
- fatigue, or feeling tired
Symptoms may start suddenly or begin gradually and become worse over time. Symptoms may vary in severity. For example, many people with microscopic colitis have four to nine bowel movements a day, but some people with microscopic colitis may have more than 10 bowel movements a day.3,4
You may experience remission—times when you have fewer symptoms or symptoms disappear. After a period of remission, you may have a relapse—a time when symptoms return or worsen.
What causes microscopic colitis?
Doctors aren’t sure what causes microscopic colitis. Experts think the following factors may play a role in causing or increasing the risk for microscopic colitis.
Abnormal immune reactions
People who have certain immune disorders—such as celiac disease, rheumatoid arthritis, or type 1 diabetes—are more likely to develop microscopic colitis. Scientists are studying the links between microscopic colitis and these immune disorders.
Research suggests certain genes increase the chance a person will develop microscopic colitis.
Taking certain medicines may increase the risk of developing microscopic colitis. These medicines include
- nonsteroidal anti-inflammatory drugs (NSAIDs)
- proton pump inhibitors (PPIs)
- selective serotonin reuptake inhibitors (SSRIs), a type of antidepressant
- hormone replacement therapy and oral contraceptives
- beta blockers, medicines that slow your heart rate
- statins, medications to lower cholesterol
Studies suggest people who smoke cigarettes are more likely to develop microscopic colitis. Among people who develop microscopic colitis, those who smoke tend to develop the disease at a younger age.
Researchers are studying other factors that may play a role in causing or worsening microscopic colitis. These factors include
- bile acid malabsorption—in which the small intestine doesn’t absorb enough bile acid and extra bile acid passes into the colon
- changes in the microbiome
- female hormones
- body mass index
 Townsend T, Campbell F, O'Toole P, Probert C. Microscopic colitis: diagnosis and management. Frontline Gastroenterology. 2019;10(4):388–393. doi: 10.1136/flgastro-2018-101040
 Yen EF, Pardi DS. Chapter 74: Microscopic colitis and other miscellaneous inflammatory and structural disorders of the colon. In: Podolsky DK, Camilleri M, Fitz G, et al, eds. Yamada’s Textbook of Gastroenterology. 6th ed. John Wiley & Sons, Ltd: 2016:1479–1494.
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