• Clinical science

Reactive arthritis (Reiter syndrome)


Reactive arthritis, (formerly known as Reiter's syndrome), is an autoimmune condition that occurs after a bacterial infection of the gastrointestinal or urinary tract. It is categorized as a seronegative spondyloarthritis because of its association with HLA-B27. Reactive arthritis primarily affects young men and usually presents with musculoskeletal or extra‑articular symptoms. The characteristic triad consists of arthritis, conjunctivitis, and urethritis. The diagnosis is based on clinical features such as patient history and physical examination; there are no specific tests for reactive arthritis. Treatment is primarily symptomatic and consists of the administration of NSAIDs, as most patients recover spontaneously.



Epidemiological data refers to the US, unless otherwise specified.



Clinical features

The classic triad of reactive arthritis (formerly called Reiter's syndrome) consists of urethritis, conjunctivitis, and arthritis, but it is only present in about a third of cases!

Can't see, can't pee, can't climb a tree!




Differential diagnoses

Differential diagnoses of infection-associated arthritis
Condition: Septic arthritis Lyme disease Reactive arthritis

At-risk groups

  • People commonly involved in outdoor activities (e.g., hunters, farmers, hikers), especially in summer months
  • Individuals with a recent gastrointestinal or urinary tract infection (usually bacterial)
  • Genetic predisposition and association with HLA-B27 (see seronegative spondyloarthritis)
  • Especially young men

Onset and course

  • Acute course with rapid onset of symptoms
  • Progressive onset that can become chronic
  • Acute onset
  • Typically resolves within 6 months, although 20–30% become chronic
  • Often self-limiting

Clinical features

  • Three stages:

Pattern of disease

  • Primarily monoarthritis, oligoarthritis is possible
  • Migratory asymmetrical polyarthropathy
    • Intermittent or persistent arthritis
    • Generally in large joints (especially knee or elbow)
  • Mono- or oligoarthritis
  • Predominately lower extremities (especially knee)
  • Migratory character if associated with gonococcal infection


The differential diagnoses listed here are not exhaustive.


There is no curative treatment. The goal of treatment is to primarily control symptoms as the disease is usually self-limiting.



  • Resolves spontaneously within a year (80% of cases)
  • High rate of recurrence (15–50% of cases)