Reactive Arthritis

Reactive arthritis is where synovitis occurs in the joints as a reaction to a recent infective trigger. It used to be known as Reiter Syndrome. Typically it causes an acute monoarthritis, affecting a single joint in the lower limb (most often the knee) presenting with a warm, swollen and painful joint.

The obvious differential diagnosis is septic arthritis (infection in the joint), however in reactive arthritis there is no infection in the joint.

The most common infections that trigger reactive arthritis are gastroenteritis or sexually transmitted infection. Chlamydia is the most common sexually transmitted cause of reactive arthritis. Gonorrhoea commonly causes a gonococcal septic arthritis.

There is a link with the HLA B27 gene. It is considered part of the seronegative spondyloarthropathy group of conditions.



  • Bilateral conjunctivitis (non-infective)
  • Anterior uveitis
  • Circinate balanitis is dermatitis of the head of the penis

TOM TIP: These features of reactive arthritis (eye problems, balanitis and arthritis) lead to the saying “can’t see, pee or climb a tree”.



Patients presenting with an acute warm, swollen, painful joint need to be treated according to the local “hot joint” policy. This will involve giving antibiotics until the possibility of septic arthritis is excluded. Aspirate the joint and send a sample for gram staining, culture and sensitivity testing to exclude septic arthritis.

The aspirated fluid can also be sent for crystal examination to look for gout and pseudogout.

Management of reactive arthritis when septic arthritis is excluded:

  • NSAIDs
  • Steroid injections into the affected joints
  • Systemic steroids may be required, particularly where multiple joints are affected

Most resolve within 6 months and don’t recur. Recurrent cases may require DMARDs or anti-TNF medications.


Last updated April 2019
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