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← Rheumatology indexChapter sections
OverviewAetiologyPathophysiologyClinical features and red flagsInvestigationsDifferential diagnosisManagementComplicationsMonitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

Reactive arthritis

Rheumatology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

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Time-critical presentation

A hot swollen joint with systemic illness requires urgent culture, acute infection treatment and source-control assessment. Eye pain, photophobia or reduced vision needs same-day ophthalmology for possible uveitis; haemodynamic instability or disseminated gonococcal infection overrides routine rheumatology care.

Overview

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 is an inflammatory spondyloarthritis triggered by infection outside the joint. Establish precise timing, organism exposure, antibiotics, sexual contacts and public-health risk. Examine joints, entheses, digits, skin, nails, mouth, genital or urinary symptoms, eyes and spine. The historical urethritis–arthritis–conjunctivitis triad is insensitive and should not be required for diagnosis.

There is no single diagnostic test. FBC, CRP and ESR support severity but may be normal. Obtain NAAT for chlamydia and gonorrhoea from the appropriate sites and stool testing when ongoing diarrhoea or public-health context justifies it. HLA-B27 is not a diagnostic infection test. Joint aspiration is essential when infection or crystals are possible; reactive synovial fluid is inflammatory but culture-negative.

Management separates infection from inflammation. Treat active sexually transmitted infection using current BASHH or local sexual-health guidance. Advise abstinence from sexual intercourse, including oral sex, until treatment is completed and symptoms have resolved; discuss and document partner notification, and offer screening for other STIs including HIV and indicated hepatitis B screening and vaccination.

Aetiology

01

Genitourinary infection

Chlamydia trachomatis is an important trigger, often with mild or unrecognised urethral or cervical symptoms before arthritis begins.

02

Enteric infection

Salmonella, Shigella, Campylobacter and Yersinia can trigger arthritis after diarrhoeal illness through immune responses rather than viable organisms within the joint.

03

Host susceptibility

HLA-B27 and other immune factors influence severity and persistence, but testing does not confirm the diagnosis or identify the triggering organism.

Pathophysiology

  1. 1
    Post-infectious immune activation

    Microbial antigens and mucosal immune signals activate inflammatory pathways after the original infection, producing sterile synovial and entheseal inflammation.

  2. 2
    Spondyloarthritis tissue pattern

    Inflammation favours lower-limb joints, entheses, whole digits, sacroiliac structures, eye and mucocutaneous sites rather than a purely symmetrical small-joint pattern.

  3. 3
    Persistence in susceptible hosts

    Ongoing antigen exposure or dysregulated immunity can sustain symptoms and evolve into chronic peripheral or axial spondyloarthritis in a minority.

Clinical features and red flags

Post-infectious lower-limb arthritis

Asymmetric knee, ankle or foot inflammation beginning after diarrhoea or genitourinary symptoms is characteristic, especially with heel enthesitis or dactylitis.

Mucocutaneous phenotype

Oral lesions, circinate balanitis, keratoderma and conjunctival symptoms support reactive arthritis but may be absent or subtle.

Anterior uveitisRed flag

Eye pain, photophobia, redness or blurred vision requires same-day ophthalmology rather than treatment as uncomplicated conjunctivitis.

Possible gonococcal infectionRed flag

Migratory pain, tenosynovitis, sparse pustules and sexual exposure requires urgent multi-site microbiology and antimicrobial assessment.

Chronic spondyloarthritis evolution

Symptoms beyond the expected episode, inflammatory back pain or recurrent enthesitis suggests a persistent axial or peripheral disease requiring specialist review.

Investigations

  1. 01
    Synovial-fluid culture and crystalsFirst step
    Why
    Exclude septic and crystal arthritis in an acutely inflamed accessible joint.
    Interpretation and limitations
    Sterile inflammatory fluid supports but does not prove reactive arthritis; prior antibiotics reduce culture yield and blood cultures may still identify infection.
  2. 02
    Chlamydia and gonorrhoea NAAT
    Why
    Identify a treatable active genitourinary trigger and support partner management.
    Interpretation and limitations
    Select urine and anatomical sites from exposure and sexual-health guidance; negative testing after delay does not exclude a prior cleared trigger.
  3. 03
    Stool microbiology
    Why
    Identify ongoing enteric infection when diarrhoea, outbreak or public-health implications persist.
    Interpretation and limitations
    A negative late sample does not exclude a preceding trigger, and a positive result does not remove the need to culture a hot joint.
  4. 04
    FBC, CRP, ESR, renal and liver profile
    Why
    Assess systemic inflammation, alternative infection and baseline safety for anti-inflammatory or DMARD treatment.
    Interpretation and limitations
    Markers are nonspecific and normal results cannot exclude reactive or septic arthritis; organ abnormalities redirect urgency.
  5. 05
    Targeted imaging

Differential diagnosis

01

Septic arthritis

Fever, bacteraemia risk or one markedly hot restricted joint requires urgent aspiration because a preceding infection does not prove reactive disease.

02

Disseminated gonococcal infection

Migratory arthritis, tenosynovitis, skin lesions and sexual exposure require site-specific testing and antimicrobial treatment rather than a sterile-arthritis assumption.

03

Psoriatic or enteropathic arthritis

Psoriasis, nail disease, established inflammatory bowel disease or recurrent axial symptoms may indicate another spondyloarthritis phenotype.

04

Crystal arthritis

Abrupt monoarthritis, tophi or CPP risk requires synovial crystal analysis, with simultaneous culture when infection remains possible.

Management

01Acute post-infectious arthritisCulture the joint and identify active infectionFirst stepNew lower-limb arthritis follows diarrhoea or genitourinary symptoms without haemodynamic instability.+
  1. 1Take sexual, gastrointestinal and medicine history, examine joint, skin, eye and entheses, and aspirate any significantly hot effusion for culture and crystals.
  2. 2Request site-appropriate chlamydia and gonorrhoea NAAT and stool tests when indicated, while assessing sepsis and disseminated infection risk.
  3. 3Treat confirmed active infection through antimicrobial and partner pathways and use comorbidity-adjusted anti-inflammatory care for sterile symptoms.
02Persistent inflammationReassess the phenotype before DMARD treatmentArthritis, enthesitis or axial symptoms remain function-limiting beyond the expected self-limited course.+
  1. 1

Complications

01

Chronic spondyloarthritis

Persistent arthritis, enthesitis or inflammatory back pain can evolve beyond the initial post-infectious episode and require disease-modifying specialist care.

02

Anterior uveitis

Painful photophobic ocular inflammation can recur and threaten vision without prompt slit-lamp assessment and topical treatment.

03

Functional and sexual-health consequences

Pain, reduced mobility, stigma, untreated infection and partner reinfection can prolong illness and create avoidable psychosocial harm.

Monitoring and follow-up

  • Review joint count, enthesitis, dactylitis, axial symptoms, function and eye symptoms over the following weeks.
  • For people under 25, arrange repeat chlamydia testing two to six months after treatment. Arrange test of cure no earlier than three weeks after treatment in pregnancy or when adherence or persistent symptoms warrants it.
  • Monitor renal, gastrointestinal and cardiovascular safety during NSAID treatment.
  • Reopen septic arthritis when fever, one-joint deterioration or poor response occurs despite an initial reactive diagnosis.
  • Refer persistent or recurrent disease for chronic spondyloarthritis assessment and DMARD monitoring.

Special situations

The trigger may be silent

Chlamydial infection can be asymptomatic, so a sensitive and nonjudgmental sexual history matters even when urethritis is absent.

The triad is optional

Arthritis does not need simultaneous urethritis and conjunctivitis to qualify; requiring all three misses many cases.

Antibiotics have a defined target

They treat active infection and transmission, while established sterile inflammation requires its own anti-inflammatory and rheumatological plan.

HLA-B27 is not confirmation

It modifies susceptibility and persistence risk but neither identifies the organism nor proves the syndrome.

Uveitis differs from conjunctivitis

Pain, photophobia and visual change are warning features that require urgent slit-lamp assessment.

Common pitfalls

  1. 01

    Diagnosing reactive arthritis without aspirating a suspicious hot joint.

  2. 02

    Requiring the complete historical triad before considering the diagnosis.

  3. 03

    Using prolonged antibiotics for sterile arthritis after a cleared enteric infection.

  4. 04

    Failing to test and manage partners after confirmed chlamydia.

  5. 05

    Treating painful photophobic eye as simple conjunctivitis.

Practice

Two practice questions

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Question 1 of 2
0 correct
RheumatologyOriginal SBA

Role of antibiotics

A patient develops asymmetric ankle and knee arthritis three weeks after treated Campylobacter diarrhoea. Stool symptoms have resolved and synovial cultures are negative. What is the best antibiotic principle?

Choose one answer, then submit
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Sources and review status6 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • NICE CKS reactive arthritisRecognition, investigation and management in UK practice.
  • NICE NG65 spondyloarthritisPeripheral disease and acute uveitis pathways.
  • BASHH chlamydia guideline 2026Current doxycycline regimen, pregnancy exception, abstinence, partner notification and retesting.
  • UK SMI B26 sterile-site fluidsSynovial culture standards when sepsis remains possible.
  • Naproxen UK product informationAdult dose and gastrointestinal, renal and cardiovascular precautions.
  • MHRA NSAID pregnancy safetyAvoidance from 20 weeks and contraindication after 28 weeks of pregnancy.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateComplete draft
Do not
prescribe prolonged antibiotics solely for arthritis after cleared enteric infection. Consider local corticosteroid only after sepsis is excluded and never inject tendon substance.

Most episodes improve over months, but recurrence or persistence requires rheumatology assessment for DMARD treatment and reclassification within spondyloarthritis. Monitor eye symptoms, axial pain, function and medication harms. Address work, mobility and sexual-health confidentiality in a non-stigmatising manner.

Key points

  • 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.
  • Aspirate a hot effusion for culture and crystals because septic arthritis, gonococcal infection and gout remain critical alternatives.
  • Treat confirmed active chlamydial or other infection according to current antimicrobial and partner-management guidance; antibiotics do not reliably cure established sterile arthritis after cleared enteric infection.
  • NSAIDs are commonly used for articular symptoms when safe. Intra-articular corticosteroid may help a selected joint only after infection is excluded; peri-entheseal injection needs an experienced clinician and must not enter tendon substance, particularly at the Achilles tendon.
  • Persistent peripheral arthritis warrants rheumatology reassessment. A conventional DMARD may be considered after infection is excluded, but evidence is limited and it should not be assumed to treat axial disease.
Why
Assess structural damage, persistent enthesitis or axial disease when symptoms do not resolve.
Interpretation and limitations
Early radiography may be normal; ultrasound or MRI supports selected questions but does not identify the infectious trigger.
Confirm that infection was adequately tested and treated, re-examine for psoriasis, bowel disease, uveitis and axial spondyloarthritis and assess adherence and function.
  • 2Refer to rheumatology. After infection is excluded, a conventional DMARD may be considered for persistent peripheral arthritis, but evidence is limited and conventional treatment should not be assumed to control axial disease.
  • 3Use specialist targeted therapy only for established ongoing spondyloarthritis meeting disease-specific criteria, with vaccination and infection precautions.
    • 03Painful red eyeProtect sightReactive-arthritis symptoms accompany eye pain, photophobia, reduced vision or ciliary redness.+
    1. 1Arrange same-day ophthalmic assessment and do not assume all ocular redness is benign conjunctivitis.
    2. 2Record visual symptoms and current immunosuppression and coordinate infection or STI information relevant to the ophthalmic differential.
    3. 3Follow ophthalmic treatment and recurrence advice while rheumatology controls the associated systemic inflammatory disease.
    Key medicines and prescribing safety2 treatments · regimens, roles and cautions+
    Anti-inflammatory symptom treatment for reactive peripheral arthritis or enthesitis while infection is assessed and the episode is monitored.

    Naproxen

    Common adult dosing is 250–500 mg orally twice daily with food for a reviewed short course when clinically suitable.

    Assess GI ulcer or bleeding, renal, cardiovascular and anticoagulant risk; use the lowest effective dose for the shortest time with gastroprotection when indicated. Avoid from 20 weeks of pregnancy unless clinically necessary and do not use from 28 weeks; follow current MHRA and product advice.

    Eradicates confirmed uncomplicated chlamydial infection and reduces transmission; it is not a stand-alone cure for established sterile arthritis.

    Doxycycline for uncomplicated chlamydia

    100 mg orally twice daily for 7 days is the usual adult regimen, subject to current sexual-health guidance and patient factors.

    Doxycycline is contraindicated for routine treatment in pregnancy; the 2026 BASHH guideline permits it only when the full course finishes before 15 weeks and no suitable alternative exists. Check allergy, oesophageal irritation, photosensitivity and interactions; provide partner-notification and STI-screening support.

    Clinical stateAwaiting review
    JurisdictionUnited Kingdom
    Provide sexual-health counselling, notification and retesting as indicated, and review for a continuing axial or peripheral spondyloarthritis phenotype.