Prognosis in the majority of patients with acute reactive arthritis is usually good, with most patients recovering in a few months. In about 15% to 30% of such patients, the disease progresses, and spondyloarthropathy and even ankylosing spondylitis develop in the following 10 to 20 years. A recurrent attack of reactive arthritis is common in patients with chlamydia-triggered arthritis, but it is rare in patients who have had enteroarthritis. In patients with chronic spondyloarthropathy without evidence of preceding infection, the disease can progress slowly into ankylosing spondylitis. When reactive chlamydia arthritis is indicated, a prolonged course of antibiotics is needed. For other forms of reactive arthritis, solid evidence in favor of antibiotic therapy is still lacking. Presence of hip pain, decreased mobility of thoracic cervical or thoracic spine, heel pain, inflammatory gut lesions, high erythrocyte sedimentation rate, positive family history, and presence of human leukocyte antigen B27 are indicators for chronicity. Sulfasalazine might be of use in chronic arthritis and ankylosing spondylitis, especially if the patient has peripheral arthritis.