The signs and symptoms of reactive arthritis generally start one to four weeks after exposure to a triggering infection. They might include:

• Pain and stiffness. The joint pain associated with reactive arthritis most commonly occurs in your knees, ankles and feet. You also might have pain in your heels, low back or buttocks.
• Eye inflammation. Many people who have reactive arthritis also develop eye inflammation (conjunctivitis).
• Urinary problems. Increased frequency and discomfort during urination may occur, as can inflammation of the prostate gland or cervix.
• Inflammation of soft tissue where it enters bone (enthesitis). This might include muscles, tendons and ligaments.
• Swollen toes or fingers. In some cases, your toes or fingers might become so swollen that they resemble sausages.
• Skin problems. Reactive arthritis can affect your skin a variety of ways, including a rash on your soles and palms and mouth sores.
• Low back pain. The pain tends to be worse at night or in the morning.

Reactive arthritis develops in reaction to an infection in your body, often in your intestines, genitals or urinary tract. You might not be aware of the triggering infection if it causes mild symptoms or none at all.

Numerous bacteria can cause reactive arthritis. Some are transmitted sexually, and others are foodborne. The most common ones include:

• Chlamydia
• Salmonella
• Shigella
• Yersinia
• Campylobacter
• Clostridium difficile

Reactive arthritis isn't contagious. However, the bacteria that cause it can be transmitted sexually or in contaminated food. Only a few of the people who are exposed to these bacteria develop reactive arthritis.

Certain factors increase your risk of reactive arthritis:

• Age. Reactive arthritis occurs most frequently in adults between the ages of 20 and 40.
• Sex. Women and men are equally likely to develop reactive arthritis in response to foodborne infections. However, men are more likely than are women to develop reactive arthritis in response to sexually transmitted bacteria.
• Hereditary factors. A specific genetic marker has been linked to reactive arthritis. But many people who have this marker never develop the condition.