Reactive arthritis is an uncommon form of arthritis that, like Guillain-Barré syndrome, often manifests in individuals who have experienced a gastrointestinal or genitourinary infection. After the patient’s body fights the infection, it turns on itself because of the development of an abnormal autoimmune response. Where Guillain-Barré syndrome attacks the nervous system, reactive arthritis attacks muscles and joints, and often almost everything else.
While reactive arthritis is associated with a wide array of symptoms, it often targets the lower body, including the legs, the sacroiliac joints where the lower spine and pelvis meet, and the lower back. It is most common in males in their 20s and 30s.
