Synopsis
Recognise sterile inflammatory arthritis following gastrointestinal or genitourinary infection, exclude septic and crystal arthritis, treat active infection appropriately, and review persistent disease for a wider spondyloarthritis phenotype.
- Reactive arthritis usually begins days to several weeks after genitourinary or enteric infection and commonly causes asymmetric lower-limb oligoarthritis, enthesitis or dactylitis.
- Ask about diarrhoea, dysuria, discharge, pelvic symptoms, sexual exposure, conjunctivitis, uveitis, oral lesions, keratoderma and heel pain without relying on the obsolete complete triad.
- A trigger may have been mild or resolved; request infection tests according to timing, symptoms and sexual-health or public-health implications.
Key red flags
Eye pain, photophobia, redness or blurred vision requires same-day ophthalmology rather than treatment as uncomplicated conjunctivitis.
Investigation priorities
Exclude septic and crystal arthritis in an acutely inflamed accessible joint.
Management branches
New lower-limb arthritis follows diarrhoea or genitourinary symptoms without haemodynamic instability.
- Take sexual, gastrointestinal and medicine history, examine joint, skin, eye and entheses, and aspirate any significantly hot effusion for culture and crystals.
- Request site-appropriate chlamydia and gonorrhoea NAAT and stool tests when indicated, while assessing sepsis and disseminated infection risk.
Key medicines
NaproxenCommon adult dosing is 250–500 mg orally twice daily with food for a reviewed short course when clinically suitable.
Doxycycline for uncomplicated chlamydia100 mg orally twice daily for 7 days is the usual adult regimen, subject to current sexual-health guidance and patient factors.