Question: What are the symptoms of microscopic colitis?
Answer: Symptoms of microscopic colitis may include

chronic, watery, nonbloodydiarrhea, which is the most common symptom
diarrhea that occurs at night
pain in theabdomen
an urgent need to have abowel 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.
Question: What causes microscopic colitis?
Answer: 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

Abnormal reactions of the immune system may play a role in causing microscopic colitis. Abnormal immune reactions lead to inflammation in the colon.

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.

Genes

Research suggests certain genes increase the chance a person will develop microscopic colitis.

Medicines

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 ofantidepressant
hormone replacement therapy and oral contraceptives
beta blockers, medicines that slow your heart rate
statins, medications to lower cholesterol

Taking certain medicines may increase the risk of developing microscopic colitis.

Smoking

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.

Other factors

Researchers are studying other factors that may play a role in causing or worsening microscopic colitis. These factors include

bile acidmalabsorption—in which thesmall intestinedoesn’t absorb enough bile acid and extra bile acid passes into the colon
changes in themicrobiome
femalehormones
infections
body mass index