What’s the difference? –ITIS/-OSIS

-itis

The ending of a word meaning “inflammation of”. Virtually every organ or tissue in the body can suffer inflammation so ‘-itis’ is by far the most common word ending in medicine. An example of its use is bronchitis (inflammation of the bronchi), encephalitis (inflammation of the brain) and cystitis (inflammation of the bladder). The ending ‘–itis’ is only used where there’s inflammation and redness.

-osis

This ending can also be used to describe a condition anywhere in the body affecting any organ or tissue. The difference between ‘-osis’ and ‘– itis’ is that there’s no inflammation associated with ‘–osis’. So arthrosis means there’s an abnormality in the joint, but no inflammation (arthritis); diverticulosis means that there are diverticula in the large intestine but no inflammation (diverticulitis).