What is Reactive Arthritis?
Reactive arthritis (ReA) is an inflammatory arthritis that develops **after** an infection elsewhere in the body, most often in the gastrointestinal or genitourinary tract. The joint inflammation is not caused by direct bacterial invasion of the joint; instead, the immune system mistakenly attacks joint tissues in response to the prior infection. Reactive arthritis is part of a broader group of conditions called the seronegative spondyloarthropathies, which also includes ankylosing spondylitis and psoriatic arthritis.
The classic presentation is a “triad” of arthritis, conjunctivitis (eye inflammation), and urethritis (painful urination). However, many patients experience only one or two of these components, and the severity can range from mild, self‑limited joint pain to chronic, disabling arthritis.
Key points
- Usually appears 1–4 weeks after the initial infection.
- More common in men than women, and in people aged 20–40.
- Strong genetic association with the HLA‑B27 allele, though not everyone who is HLA‑B27 positive develops ReA.
Common Causes
Reactive arthritis follows an infection, most frequently caused by the following organisms. The list includes the eight‑to‑ten most common triggers:
- Chlamydia trachomatis – a sexually transmitted bacterium; the leading cause of genitourinary‑related ReA.
- Salmonella spp. – especially S. enteritidis and S. typhimurium, common after contaminated food.
- Shigella spp. – bacterial dysentery, often linked to travel or poor sanitation.
- Campylobacter jejuni – a leading cause of bacterial gastroenteritis worldwide.
- Yersinia enterocolitica – can cause diarrheal illness and is a recognized trigger for ReA.
- Ureaplasma urealyticum – a genital tract organism that can provoke arthritis after urogenital infection.
- Clostridium difficile – toxin‑producing bacteria causing severe colitis; increasingly reported as a ReA trigger.
- Enteric viruses (e.g., adenovirus, norovirus) – rare but documented in case reports.
- Mycoplasma pneumoniae – a respiratory pathogen; may cause ReA in a minority of cases.
- Other less common bacteria – such as Streptococcus spp. or Staphylococcus aureus when they cause systemic infection.
Associated Symptoms
Reactive arthritis rarely affects only the joints. The immune response can involve several organ systems, producing a spectrum of extra‑articular features:
- Arthritis – asymmetric, typically affecting the knees, ankles, and feet; can also involve the lower back (sacroiliac joints).
- Enthesitis – inflammation where tendons or ligaments insert into bone (e.g., Achilles tendon).
- Conjunctivitis or uveitis – redness, itching, tearing, or pain in the eye; vision changes warrant urgent ophthalmology review.
- Urethritis or cervicitis – burning on urination, discharge, or pelvic pain.
- Skin lesions – keratoderma blennorrhagicum (hyperkeratotic lesions on soles or palms) or circinate balanitis (ulcerative lesions on the glans penis).
- Mucosal ulcers – mouth or genital ulcers that can mimic other inflammatory conditions.
- Fever, fatigue, and malaise – especially during the acute phase.
- Low back pain – may indicate sacroiliac involvement, which can become chronic.
When to See a Doctor
Most cases of reactive arthritis improve with time, but early medical evaluation can prevent complications and reduce pain. Seek professional care if you notice any of the following:
- Joint pain and swelling that began within 1–4 weeks after a diarrhea, food poisoning, or a sexually transmitted infection.
- Persistent eye redness, pain, or visual changes.
- Painful urination, genital discharge, or pelvic discomfort lasting more than a few days.
- Swelling in the heel, lower back, or the area where a tendon attaches to bone (suggesting enthesitis).
- Fever ≥ 100.4 °F (38 °C) that does not resolve within 48 hours.
- Symptoms that worsen after the initial infection appears to have cleared.
Timely treatment can shorten the acute phase, limit joint damage, and address extra‑articular manifestations.
Diagnosis
There is no single test that definitively proves reactive arthritis; diagnosis is clinical, supported by laboratory and imaging studies.
1. Clinical History
- Recent (< 1‑4 weeks) gastrointestinal or genitourinary infection.
- Pattern of asymmetric arthritis affecting lower extremities.
- Presence of conjunctivitis, urethritis, or characteristic skin lesions.
- Family history of HLA‑B27–associated diseases.
2. Physical Examination
- Joint swelling, warmth, and limited range of motion.
- Enthesitis (tenderness at tendon insertions).
- Eye examination for conjunctival injection or uveitis.
3. Laboratory Tests
- Complete blood count (CBC) – may show mild leukocytosis.
- Erythrocyte sedimentation rate (ESR) and C‑reactive protein (CRP) – markers of inflammation, usually elevated.
- HLA‑B27 typing – positive in 50‑80 % of ReA patients, but a negative result does not rule it out.
- Microbiologic testing – stool culture, urine nucleic acid amplification test (NAAT) for Chlamydia, or PCR for other pathogens to identify the precipitating infection.
- Synovial fluid analysis – performed if joint effusion is prominent; typically shows inflammatory fluid without bacteria (sterile). This helps exclude septic arthritis.
4. Imaging
- X‑ray – may be normal early on; later can show erosions or joint space narrowing.
- Ultrasound – useful for detecting synovitis, effusion, or enthesitis.
- MRI – provides detailed view of sacroiliac joints and early bone marrow edema.
5. Diagnostic Criteria (CDC/American College of Rheumatology)
While formal criteria are evolving, most clinicians use a combination of:
- Antecedent infection + arthritis (≥ 1 joint).
- Plus at least one extra‑articular manifestation (conjunctivitis, urethritis, or skin lesion).
- And exclusion of other causes (septic arthritis, gout, rheumatoid arthritis, etc.).
Treatment Options
Treatment aims to relieve pain, control inflammation, eradicate the underlying infection (if still present), and prevent chronic joint damage.
1. Treat the Trigger Infection
- Chlamydia – doxycycline 100 mg PO twice daily for 14 days (or azithromycin 1 g PO single dose). CDC recommends treatment even if the infection appears cleared, as it reduces ReA risk.
- Gram‑negative enteric bacteria (Salmonella, Shigella, Campylobacter, Yersinia) – usually self‑limited; antibiotics are reserved for severe or invasive disease.
2. Non‑steroidal Anti‑Inflammatory Drugs (NSAIDs)
First‑line for pain and inflammation. Examples:
- Ibuprofen 400‑600 mg PO every 6‑8 hours
- Naproxen 250‑500 mg PO twice daily
Use the lowest effective dose, and consider gastro‑protection (e.g., pantoprazole) in patients at risk for ulcer disease.
3. Corticosteroids
- Localized joint injections (e.g., triamcinolone) for severe mono‑ or oligo‑arthritis.
- Short oral courses (prednisone 10‑20 mg daily tapered over 2‑4 weeks) if NSAIDs are insufficient or contraindicated.
4. Disease‑Modifying Antirheumatic Drugs (DMARDs)
Considered when arthritis persists beyond 3–6 months or becomes polyarticular:
- Sulfasalazine 500‑1000 mg PO BID.
- Methotrexate 7.5‑15 mg weekly, with folic acid supplementation.
5. Biologic Therapies
For refractory disease, tumor necrosis factor (TNF) inhibitors such as etanercept, infliximab, or adalimumab have demonstrated efficacy. Use under rheumatology supervision, with screening for latent TB and hepatitis.
6. Physical Therapy & Home Care
- Gentle range‑of‑motion exercises to maintain joint flexibility.
- Low‑impact aerobic activities (swimming, cycling) to improve overall conditioning.
- Ice packs to swollen joints for 15‑20 minutes, 3‑4 times daily.
- Compression sleeves or orthotics for foot/ankle involvement.
7. Symptomatic Eye Care
If conjunctivitis or uveitis develops, an ophthalmologist may prescribe topical steroids or cycloplegic drops. Prompt treatment prevents vision loss.
Prevention Tips
Because reactive arthritis follows an infection, preventive strategies focus on reducing the risk of the triggering illnesses:
- Practice safe sex – correct condom use, routine screening for Chlamydia and gonorrhea, especially in sexually active individuals under 30.
- Food safety – wash fruits/vegetables, cook meats to safe internal temperatures, avoid cross‑contamination.
- Hand hygiene – wash hands with soap for at least 20 seconds after using the restroom or handling raw food.
- Travel precautions – use bottled water and properly cooked foods in regions with poor sanitation.
- Prompt treatment of infections – seek medical care for persistent diarrhea, dysuria, or genital discharge.
- Vaccinations – stay up to date with vaccines that reduce gastrointestinal infections (e.g., rotavirus for children, hepatitis A).
- Maintain a healthy immune system – balanced diet, regular exercise, adequate sleep, and management of chronic illnesses (diabetes, HIV).
Emergency Warning Signs
If any of the following occur, seek immediate medical attention (go to the emergency department or call 911):
- Severe, rapidly worsening joint pain with high fever (> 101.5 °F / 38.6 °C) – could indicate septic arthritis.
- Sudden loss of vision, eye pain, or photophobia – possible acute uveitis or intra‑ocular infection.
- Intense lower back pain accompanied by numbness, weakness, or loss of bladder/bowel control – may signal spinal cord compression.
- Swelling and redness of a single joint that is extremely tender to touch, especially the knee or wrist.
- Persistent, profuse diarrhea or vomiting leading to dehydration (dry mouth, dizziness, scant urine).
- Shortness of breath or chest pain while having an infection – rare but could be a sign of systemic inflammatory response.
These red‑flag symptoms require urgent evaluation to rule out life‑threatening complications.
**References**
- Mayo Clinic. “Reactive arthritis.” Accessed May 2026.
- Centers for Disease Control and Prevention. “Sexually Transmitted Infections Treatment Guidelines, 2021.” Accessed May 2026.
- National Institute of Arthritis and Musculoskeletal and Skin Diseases. “Reactive Arthritis.” Accessed May 2026.
- Cleveland Clinic. “Reactive Arthritis: Symptoms, Causes, and Treatment.” Accessed May 2026.
- World Health Organization. “Guidelines for the Treatment of Bacterial Gastroenteritis.” 2022. Accessed May 2026.
- American College of Rheumatology. “2022 Recommendations for the Management of Reactive Arthritis.” *Arthritis Care & Research*, 2022.