Reactive arthritis

Last updated 28 Mar 2026

Introduction

Reactive arthritis (ReA) is an acute inflammatory arthritis triggered by a remote infection, typically of the gastrointestinal or genitourinary tract. It is characterised by the classic triad of arthritis, urethritis, and conjunctivitis (formerly known as Reiter's syndrome), although the complete triad is present in only a minority of patients. In Australia, the most common triggers include Chlamydia trachomatis (genitourinary), Salmonella, Campylobacter, Shigella, and Yersinia (gastrointestinal).

Reactive arthritis predominantly affects young adults (age 20–40 years) and is strongly associated with HLA-B27 positivity (present in 60–80% of patients). The condition is usually self-limiting, resolving within 3–6 months in most patients. However, 10–20% of patients develop chronic disease requiring ongoing treatment. Management is primarily symptomatic with NSAIDs, with antibiotics reserved for treatment of the triggering infection where applicable.

Pathophysiology

Triggering Infections

Genitourinary (sexually transmitted): Chlamydia trachomatis (most common STI trigger). Presents 1–4 weeks after urogenital infection.
Gastrointestinal (enteric): Salmonella, Campylobacter, Shigella, Yersinia, Clostridioides difficile. Presents 1–4 weeks after gastroenteritis.
Respiratory: Chlamydia pneumoniae, Mycoplasma pneumoniae (less common triggers).

Immune Mechanism

The exact mechanism involves bacterial antigen (or bacterial DNA) seeding of the synovium, triggering an aberrant immune response. HLA-B27 positivity predisposes to more severe and chronic disease. The joint inflammation is sterile (no viable organisms in the joint) but driven by bacterial antigen-specific T cells.

Clinical Presentation

Arthritis Features

Pattern: Oligoarticular (2–4 joints), asymmetrical, predominantly lower limb (knees, ankles, feet). Onset 1–4 weeks after triggering infection. Enthesitis: Achilles tendon insertion, plantar fascia (heel pain common). Dactylitis: Sausage digit swelling of toes. Axial involvement: Sacroiliitis or inflammatory back pain in HLA-B27-positive patients.

Extra-Articular Manifestations

Ocular: Conjunctivitis (mild, usually resolves spontaneously), anterior uveitis (less common but more severe). Mucocutaneous: Keratoderma blennorrhagicum (hyperkeratotic skin lesions on soles/palms), circinate balanitis (penile lesions in men), oral ulcers. Urogenital: Urethritis, cervicitis (often mild or asymptomatic). Systemic: Low-grade fever, fatigue, weight loss in acute phase.

Investigations

Essential
Inflammatory Markers (ESR, CRP)
Elevated in active disease. Monitor to assess treatment response. May normalise quickly with NSAID therapy.
Essential
STI Screen (Chlamydia, Gonorrhoea)
Urine or urethral/cervical swab for Chlamydia trachomatis by PCR. Essential if sexually active and arthritis follows urogenital symptoms. Treat confirmed infection with antibiotics.
Essential
Stool Culture
If history of gastroenteritis preceding arthritis. Culture for Salmonella, Campylobacter, Shigella, Yersinia. Positive culture confirms enteric trigger.
Available
HLA-B27 Testing
Positive in 60–80% of ReA patients. Predicts more severe, prolonged, or chronic disease course. Useful for prognosis and monitoring.
Available
Joint Aspiration
If diagnostic uncertainty or to exclude septic arthritis. Aspirate shows inflammatory fluid (WBC 10,000–50,000 cells/mm³, predominantly PMNs). Culture should be negative (sterile inflammation).

Severity Grading

MILD

Self-Limiting Disease

1–2 joints affected. Minimal functional impairment. Systemic symptoms absent or mild. Expected to resolve within 3–6 months.

Primary care; NSAIDs; treat underlying infection

MODERATE

Significant Joint Involvement

Multiple joints affected. Enthesitis or dactylitis present. Moderate functional limitation. Systemic features present.

Primary care with rheumatology consultation; NSAIDs; consider intra-articular corticosteroids

SEVERE / CHRONIC

Persistent or Severe Disease

Disease persisting >6 months. Significant functional impairment. Axial involvement. HLA-B27 positive with risk of progression to axSpA.

Rheumatology specialist; conventional DMARDs or biologic therapy

Directed Therapy

Antibiotic Therapy for Triggering Infection

Treat confirmed triggering infection with appropriate antibiotics. Antibiotic treatment does NOT shorten the course of reactive arthritis once established. However, treating active urogenital infection may prevent recurrence.

💊

Doxycycline

Doxycycline · Tetracycline antibiotic

IndicationConfirmed Chlamydia trachomatis infection

Adult Dose100 mg twice daily

RouteOral

Duration7 days (uncomplicated urogenital Chlamydia)

NotesTreat sexual partners. Screen for other STIs concurrently. Does not shorten arthritis duration once arthritis has developed.

PBS Status✓ PBS General Benefit

Anti-Inflammatory Therapy

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Naproxen

Naprosyn® · NSAID

Adult Dose500 mg twice daily

RouteOral

DurationUntil symptom resolution (typically 3–6 months)

NotesFirst-line for joint inflammation. Take with food. Use with gastroprotection (PPI) if risk factors present.

PBS Status✓ PBS General Benefit

DMARDs for Chronic Disease (>6 months)

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Sulfasalazine

Salazopyrin® · DMARD

Adult Dose500 mg twice daily, increasing to 1–1.5 g twice daily over 4 weeks

RouteOral

Duration6–12 months; review need for ongoing therapy

NotesFirst-line DMARD for chronic ReA. Monitor FBC and LFTs at baseline, 4 weeks, then 3-monthly. Avoid in sulfa allergy.

PBS Status✓ PBS General Benefit

Acute Management

Initial Assessment

When reactive arthritis is suspected: (1) Obtain detailed history of preceding infection (gastroenteritis, urogenital symptoms, respiratory illness) within the preceding 1–4 weeks. (2) Perform joint examination — oligoarticular, asymmetric, lower limb predominant. (3) Check for extra-articular features (eye symptoms, skin lesions, oral ulcers). (4) Arrange STI screen if urogenital trigger possible. (5) Blood tests: ESR, CRP, FBC, HLA-B27.

Intra-Articular Corticosteroids

For significant joint inflammation not responding to NSAIDs, intra-articular triamcinolone (20–40 mg) provides rapid relief. Avoid systemic corticosteroids unless required for severe extra-articular manifestations. Can be repeated in the same joint if relapse occurs.

Eye Involvement

Conjunctivitis: usually mild; warm compress and artificial tears. Uveitis: urgent ophthalmology referral. Treat with topical corticosteroids and mydriatics; systemic therapy for severe uveitis.

Monitoring and Follow-Up

Short-Term Follow-Up

At 4–6 weeks: Assess response to NSAIDs. Check if triggering infection treated. Review STI results and arrange partner treatment if Chlamydia confirmed. If symptoms not improving, consider intra-articular corticosteroid injection. Reassure patient of usually self-limiting course.

Long-Term Follow-Up

At 3 months: If symptoms persist beyond 3 months, consider referral to rheumatology. Commence DMARD (sulfasalazine) if chronic disease developing. At 6 months: If disease persists beyond 6 months, specialist assessment. Consider biologic therapy (TNF inhibitor) if HLA-B27 positive with axial involvement or persistent high disease activity despite DMARDs.

Risk of Progression

10–20% of patients with reactive arthritis develop chronic disease. HLA-B27 positivity predicts higher risk. Monitor for development of axSpA features (inflammatory back pain, sacroiliitis) during follow-up.

Special Populations

👶 Paediatrics

NSAIDs in childrenNaproxen (10–15 mg/kg/day) or ibuprofen (30–40 mg/kg/day) are appropriate. Avoid aspirin (Reye syndrome risk). Monitor renal function with prolonged use.

Antibiotic treatmentTreat confirmed triggering infection with age-appropriate antibiotics. Paediatric dosing adjustments required for doxycycline (avoid <8 years), azithromycin preferred in younger children.

🤰 Pregnancy

NSAIDsAvoid in third trimester (risk of premature ductus arteriosus closure). Paracetamol is safe throughout pregnancy for symptom relief.

Chlamydia treatmentAzithromycin 1 g single dose preferred over doxycycline in pregnancy (doxycycline contraindicated). Treat sexual partners.

Aboriginal and Torres Strait Islander Health Considerations

Reactive arthritis may be more prevalent in Aboriginal and Torres Strait Islander communities due to higher rates of STIs (particularly Chlamydia trachomatis) and enteric infections. Addressing the root causes of infection is essential for prevention. STI and enteric infection management should be integrated with ReA management.

STI Prevalence

High rates of Chlamydia in remote communities contribute to increased ReA risk. Integrate routine STI screening into primary care visits. Treat contacts and partners. Provide culturally sensitive sexual health education.

Diagnostic Barriers

Limited access to HLA-B27 testing and rheumatology assessment in remote areas. Utilise clinical diagnosis tools. Arrange telehealth rheumatology if available. Early referral if disease appears to be progressing beyond 3 months.

Enteric Infections

Higher rates of foodborne illness and enteric infections in some communities. Improve food safety and water quality. Educate communities on safe food handling. Treat gastroenteritis episodes promptly.

Cultural Considerations

Discussions about STIs may be sensitive. Use culturally appropriate, non-judgmental communication. Involve Aboriginal health workers. Provide materials in local languages where available.

Antimicrobial Stewardship

Antibiotic Use in Reactive Arthritis

Antibiotics play a limited role in ReA management. The key principle is to treat the identified triggering infection, not to use antibiotics as disease-modifying agents for the arthritis itself. Extended antibiotic therapy does not improve musculoskeletal outcomes in most cases.

Appropriate Use

Treat confirmed or suspected Chlamydia trachomatis urogenital infection with doxycycline 100 mg BD for 7 days (or azithromycin 1 g single dose)
Contact tracing and partner notification essential for sexually acquired cases
Treat confirmed enteric trigger if organism susceptible and clinical picture warrants treatment
Do not empirically prescribe antibiotics for ReA without identified triggering infection

Inappropriate Use — Avoid

Do not use long-term antibiotics to suppress arthritis activity — no evidence of benefit
Avoid repeating antibiotic courses for recurrent ReA without confirmed active infection
NSAIDs and DMARDs, not antibiotics, are the cornerstone of arthritis management

ℹ️

ACSQHC Stewardship Standard 3: Antibiotic prescribing should follow culture-directed, infection-specific principles. Reactive arthritis is an immune-mediated post-infectious condition and does not respond to extended antibiotic therapy.

References

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