What is reactive arthritis? 

Reactive arthritis happens when an infection causes joint pain and swelling. A bacterial infection in the digestive or urinary tract or the genitals usually triggers the condition, but arthritis symptoms typically do not start until a few weeks after you have recovered from the infection.

The most common features of reactive arthritis are inflammation of the joints (especially the knees and ankles), eyes, and urinary tract, but not everyone gets all three, or they might not happen at the same time.

Who gets reactive arthritis?

Anyone can get reactive arthritis. Certain factors increase the risk of the condition, including:

  • Sex. Men are more likely to develop it after having a sexually transmitted infection. Men and women are equally affected if the condition is from a gastrointestinal infection.
  • Age. It occurs most often in people between ages 20 and 40.
  • Genetics. People who have a certain gene have a higher risk of getting reactive arthritis and of having more severe and more long-lasting symptoms.
  • HIV infection. Having AIDS or being infected with HIV increases the risk of reactive arthritis.

What are the symptoms of reactive arthritis?

Reactive arthritis symptoms typically start 1 to 6 weeks after an infection of the digestive or urinary tract or genitals, but the infection has usually gone away by the time you get arthritis symptoms. The main symptoms are:

  • Joint pain and stiffness. Joints may become painful, red, and swollen, especially in the knees and ankles. You may feel stiff in the morning and feel pain at night. The affected joints are usually on one side of the body.
  • Inflammation of the urinary tract. Increased urinary frequency and burning while urinating are signs of urinary tract inflammation. 
  • Eye inflammation. Eyes may have redness, pain, burning, itching, crusted eyelids, blurred vision, or sensitivity to light.

Not everyone with reactive arthritis will have inflammation in all three areas of the body, or they might not happen at the same time. Some people with reactive arthritis have mild symptoms, while others have severe symptoms that limit daily activities.

What causes reactive arthritis?

Reactive arthritis is triggered by a bacterial infection. It is separate from the infection and typically happens after the infection has gotten better.

Not everyone who gets these infections will get reactive arthritis. Doctors do not fully understand why some people are more likely to get the condition, but both genes and things in the environment likely play a role.