Polyarthritis is any type of arthritis that involves 5 or more joints simultaneously.

It can be associated with autoimmune conditions; it may be experienced at any age and is not sex specific.

[1] Polyarthritis is often caused by an auto-immune disorder such as rheumatoid arthritis, psoriatic arthritis, and lupus erythematosus, or other inflammatory rheumatic diseases, like crystal arthropathies.

[2] Arthritis caused by bacterial infection of the joint is termed septic arthritis and does not commonly affect multiple joints.

This form or arthritis is called reactive and often coexists with inflammation of the urethra, and of the conjuctiva in the eye.