Q: When reading articles about arthritis, I often come across the word "flare." What is the definition of flare?

A: The definition of “flare” is a worsening of the disease process. If you have arthritis, you've probably experienced a flare at one time or another – your disease seems to be well under control for a while, then suddenly your joints become inflamed and painful. You may experience general malaise and fatigue. 

The cause of a flare varies depending on the specific disease in question. In rheumatoid arthritis, for example, a flare can be related to natural (but poorly understood) fluctuations in the immunological processes that drive inflammation. In osteoarthritis, flares may be induced by local trauma to the joint.

John A. Hardin, MD, Rheumatologist