Microscopic colitis is a type of inflammation of the colon, or large intestine, that can cause watery diarrhea and cramping. While it can be painful and unpleasant, it's much less severe than other types of inflammatory bowel disease.
It's called microscopic because the inflammation is too small to see with the naked eye. The only way your doctor can diagnose it is to take a sample of tissue and check it under a microscope.
There are two types of microscopic colitis: