Reactive arthritis is joint pain and swelling triggered by an infection in another part of your body — most often your intestines, genitals or urinary tract.
Your knees and the joints of your ankles and feet are the usual targets of reactive arthritis. Inflammation also may affect your eyes, skin and urethra when you have reactive arthritis.
Although reactive arthritis is sometimes called Reiter's syndrome, Reiter's is actually a specific type of reactive arthritis. In Reiter's, inflammation typically affects the eyes and urethra, as well as your joints.
Reactive arthritis isn't common. For most people, signs and symptoms of reactive arthritis come and go, eventually disappearing within 12 months.