Reactive Arthritis
Also known as: Reiter's syndrome, Post-infectious arthritis
Reactive arthritis is joint pain and swelling triggered by an infection somewhere else in the body, most often in the intestines (from food poisoning bacteria such as Salmonella, Shigella, Campylobacter or Yersinia) or the genitourinary tract (usually Chlamydia). The joints themselves are not infected; instead the immune system's response to the infection misfires and inflames joints, tendons, eyes and sometimes the skin and urinary tract. Symptoms typically begin 1 to 4 weeks after the infection and usually affect the knees, ankles and feet asymmetrically. Most people recover within a few months to a year, though some have recurrent or long-lasting symptoms, particularly those who carry the HLA-B27 gene.
At a Glance
- Common symptoms
- Pain and swelling in a few large joints, especially the knees, ankles and feet, often on one side more than the other, Heel pain or swelling of an entire finger or toe (sausage digit), Low back and buttock pain, worse at night and in the morning
- Main treatments
- Antibiotics to clear a persisting infection, particularly Chlamydia (partners also need treatment), Nonsteroidal anti-inflammatory drugs as the main treatment for joint pain and swelling, Corticosteroid injections into severely inflamed joints, or short courses of oral steroids
- Category
- Musculoskeletal · Uncommon; develops in a small minority of people after certain gut or genital infections, mostly young adults
- See a doctor if
- Joint pain and swelling starting within weeks of diarrhoea, a urinary infection or a new sexual contact
Symptoms
Causes
- An immune reaction to a recent gastrointestinal infection with bacteria such as Salmonella, Shigella, Campylobacter or Yersinia
- An immune reaction to a sexually transmitted infection, most commonly Chlamydia trachomatis
- Genetic predisposition, particularly the HLA-B27 gene
- Less commonly, other infections including respiratory Chlamydia pneumoniae or Clostridioides difficile
Risk Factors
- Carrying the HLA-B27 gene
- Age 20 to 40
- Being male, particularly for the sexually acquired form
- Recent food poisoning or unprotected sex
- HIV infection
- A family history of spondyloarthritis
Diagnosis
- Medical history linking joint symptoms to a recent gut or genitourinary infection
- Physical examination of joints, tendons, eyes, skin and genitals
- Blood tests for inflammation (ESR, CRP) and the HLA-B27 gene, and tests to exclude rheumatoid arthritis and gout
- Urine, stool or swab tests to identify the triggering infection
- Joint fluid analysis to exclude infection in the joint, and X-rays or ultrasound in persistent cases
Treatment
- Antibiotics to clear a persisting infection, particularly Chlamydia (partners also need treatment)
- Nonsteroidal anti-inflammatory drugs as the main treatment for joint pain and swelling
- Corticosteroid injections into severely inflamed joints, or short courses of oral steroids
- Disease-modifying drugs such as sulfasalazine or methotrexate for symptoms lasting more than a few months
- Biologic medications (TNF inhibitors) for severe or persistent disease
- Eye drops or specialist treatment for uveitis to protect vision
- Supportive: physiotherapy and regular exercise to maintain joint range of motion and muscle strength
Prevention
- Practise safe sex and get tested and treated promptly for sexually transmitted infections
- Handle and cook food safely to avoid bacterial food poisoning
- Wash hands thoroughly, especially when travelling or after using the toilet
- Seek prompt treatment for diarrhoeal illnesses and urinary symptoms
- If you have had reactive arthritis, be especially careful to avoid repeat infections that can retrigger it
When to See a Doctor
- Joint pain and swelling starting within weeks of diarrhoea, a urinary infection or a new sexual contact
- A painful red eye or blurred vision, which needs urgent assessment to prevent damage
- A single hot, swollen joint with fever, which could be a joint infection
- Joint symptoms lasting more than a few weeks or interfering with daily life
- Recurrent episodes of arthritis
Frequently Asked Questions
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