Definition
Sterile inflammatory arthritis following a remote infection, usually of the gastrointestinal or urogenital tract. Reiter syndrome is the historical term for the triad of arthritis, urethritis and conjunctivitis, and the eponym has been abandoned.
Aetiology
- Urogenital Chlamydia trachomatis
- Enteric Salmonella, Shigella, Yersinia and Campylobacter
- HLA-B27 linked to more severe and chronic disease
- One of the seronegative spondyloarthropathies
Epidemiology
- Young adults
- Male predominance after urogenital infection, equal sex ratio after enteric infection
Clinical Features
- Onset 2 to 4 weeks after the triggering infection
- Asymmetric lower limb oligoarthritis, the knee and ankle most often
- Enthesitis at the Achilles insertion and plantar fascia
- Dactylitis, the sausage toe
- Sacroiliitis and inflammatory back pain
- Conjunctivitis, anterior uveitis, urethritis or cervicitis
- Keratoderma blennorrhagicum, circinate balanitis, oral ulcers and nail dystrophy
Investigations
- Raised ESR and CRP
- Joint aspiration excludes septic and crystal arthritis
- Synovial fluid is inflammatory and culture negative
- Urine nucleic acid amplification test for Chlamydia and stool culture
- Rheumatoid factor negative
- HLA-B27 is not a diagnostic test for acute disease
Differential Diagnosis
- Septic arthritis, including gonococcal arthritis
- Gout and pseudogout
- Psoriatic arthritis and ankylosing spondylitis
- Lyme arthritis
- Post streptococcal arthritis
Management
- NSAIDs. First line for arthritis and enthesitis
- Intra-articular corticosteroid. Persistent monoarthritis once infection is excluded
- Antibiotics. Treat active Chlamydia and sexual partners, with no proven benefit in enteric reactive arthritis
- Disease modifying drugs. Sulfasalazine or methotrexate for chronic disease beyond 6 months
- Biologic therapy. Anti-TNF agents for refractory disease under rheumatology care
Prognosis
- Most episodes settle within months
- 15 to 20% develop chronic or relapsing disease
Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 19 October 2026.