Causes

It's not clear what causes the inflammation of the colon found in microscopic colitis. Researchers believe that the causes may include:

• Medications that can irritate the lining of the colon.
• Bacteria that produce toxins that irritate the lining of the colon.
• Viruses that trigger inflammation.
• Autoimmune disease associated with microscopic colitis, such as rheumatoid arthritis, celiac disease or psoriasis. Autoimmune disease occurs when your body's immune system attacks healthy tissues.
• Bile acid not being properly absorbed and irritating the lining of the colon.