Arthritis that is caused by the body’s response to an infection. (Reactive arthritis is sometimes referred to as Reiter syndrome.) Reactive arthritis differs from septic arthritis, in which an infection actually gets into the joints. In reactive arthritis, symptoms usually occur two to four weeks after a gastrointestinal infection (such as a stomach flu) or the genitourinary tract (such as a sexually transmitted disease). The first symptom is typically inflammation of the urethra (the tube that carries urine from the bladder), which causes burning or stinging during urination and/or a sense of urinary urgency. This may be followed weeks later by low-grade fever, conjunctivitis (eye inflammation), and pain and inflammation in the joints. Joints commonly affected include the knees, ankles, feet, and fingers. Low back pain is also common. Affected fingers and toes often take on a puffed-up “sausage” appearance. A psoriasis-like rash also occurs in some people with reactive arthritis, and eye problems such as uveitis (inflammation of the iris) are sometimes seen. Depending upon the cause of the reactive arthritis, men can be overwhelmingly more likely to develop it. For example, about 90% of the people who develop reactive arthritis after contracting chlamydia are men, while when dysentery is the cause, equal numbers of men and women get it.
Doctors diagnose reactive arthritis on the basis of the symptoms just described. In addition, a doctor might take a blood test for inflammatory markers in the blood and/or for the HLA-B27 gene, common in people with reactive arthritis. A doctor may also take a sample of joint (synovial) fluid, which may give clues as to the cause of the arthritis. The joint fluid can be tested for levels of white blood cells, which are often elevated in people with reactive arthritis.
Typically, doctors treat reactive arthritis with antibiotics to address the underlying infection. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil, Motrin IB) and other pain relievers are also cornerstones of treatment. If there is persistent joint pain, the doctor may inject a corticosteroid into the joint for temporary relief; oral corticosteroids such as prednisone are also common. And disease-modifying drugs called tumor necrosis factor–blockers (TNF-blockers), which include etanercept (Enbrel) and infliximab (Remicade), may be used to reduce pain and inflammation. In addition, physical therapy is sometimes used to relieve pain, promote joint mobility, and maintain muscle strength. Most cases of reactive arthritis go away within a year, although in about 15% of cases the arthritis becomes chronic.