@may Hello, it is a condition in which inflammation takes place in various parts of the body. It usually develops following an infection, and in most cases clears up in a few months. It's not known exactly what causes reactive arthritis, but it's thought to be the result of the immune system reacting to an infection. Another cause of reactive arthritis is genetic factors. Reactive arthritis isn't common. For most people, signs, and symptoms come and go, eventually disappearing within 12 months. Earlier signs and symptoms of reactive arthritis are eye inflammation, low back pain, and swelling in the toes.