Reactive arthritis is a condition triggered by an infection that occurs in another part of your body — most often your intestines, genitals or urinary tract.

Painful and swollen joints are a defining feature of reactive arthritis, which typically targets the knees, ankles and feet. Reactive arthritis can also cause inflammation in your eyes, skin and the tube that carries urine from your bladder (urethra).

Reactive arthritis is also sometimes called Reiter syndrome, although this term more accurately refers to a subtype of reactive arthritis that primarily affects the joints, eyes and urethra.

Reactive arthritis occurs in about 30 people per 100,000. For most people, signs and symptoms of reactive arthritis come and go, eventually disappearing within 12 months.

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Inflammation sites

The signs and symptoms of reactive arthritis generally start one to three weeks after exposure to a triggering infection.

Musculoskeletal

• Joint pain, usually in your knees, ankles and feet
• Heel pain
• Pain and swelling at the back of your ankle
• Swollen toes or fingers, which may look like sausages
• Pain in your low back or buttocks

Reproductive and urinary

• Pain or burning during urination
• Increased frequency of urination
• Inflammation of the prostate gland (prostatitis)
• Inflammation of the cervix (cervicitis)

Eyes, mouth and skin

• Eye inflammation (conjunctivitis)
• Inflammation of your inner eye (uveitis)
• Mouth ulcers
• Skin rashes

Certain factors increase your risk of reactive arthritis:

• Sex. Reactive arthritis occurs most frequently in men 20 to 40 years old. Though women also can acquire reactive arthritis, they usually have milder signs and symptoms. Women and men are equally likely to develop reactive arthritis in reaction to food-borne infections. However, men are more likely than are women to develop reactive arthritis in response to sexually transmitted bacteria.
• Hereditary factors. Reactive arthritis may have a genetic component because many people with the condition also have a certain molecule on the surfaces of their cells that can be inherited. Having this genetic marker — called the human leukocyte antigen B27 (HLA-B27) — doesn't mean that you'll develop reactive arthritis, but it can increase your chances of developing reactive arthritis if you're exposed to specific bacteria.

Reactive arthritis develops in reaction to an infection in another part of your body, often in your intestines, genitals or urinary tract. You may not be aware of the triggering infection because it may cause only mild symptoms or none at all.

Numerous bacteria can cause reactive arthritis. The most common ones include:

• Chlamydia
• Salmonella
• Shigella
• Yersinia
• Campylobacter

Reactive arthritis isn't contagious. However, the bacteria that cause it can pass from person to person, such as during sexual contact and food preparation. But only a few of the people who are exposed to these bacteria develop reactive arthritis.

Signs and symptoms of reactive arthritis may last three to 12 months. However, many people can control their signs and symptoms with treatment and return to their normal routine within two to six months of the onset of reactive arthritis.

Up to half the people with reactive arthritis redevelop signs and symptoms after their initial condition disappears. It's possible that relapses are the result of reinfection. Arthritis and back pain are the symptoms that reappear most often, but urogenital and eye inflammation also tend to recur.

While you may initially consult your family physician, he or she may refer you to a rheumatologist — a doctor who specializes in arthritis — for further evaluation.

What you can do
You may want to write a list that includes:

• Detailed descriptions of your symptoms
• Information about medical problems you've had in the past
• Information about the medical problems of your parents or siblings
• All the medications and dietary supplements you take
• Questions you want to ask the doctor

What to expect from your doctor
During the physical exam, your doctor may check:

• The range of motion in your affected joints
• Your skin for rashes
• Your eyes for inflammation

Reactive arthritis can go undiagnosed for a long time because your signs and symptoms may be mild. While there is no single test that will confirm a diagnosis of reactive arthritis, the results of a variety of tests can be taken together to rule out other conditions that may be causing your signs and symptoms.

Blood tests
Samples of your blood can reveal:

• Infections. Sometimes, the triggering bacteria are still evident in your blood. But in many cases, your reactive arthritis symptoms begin long after you've recovered from the infection.
• Inflammation. Your doctor may check a blood test to see if you have an elevated sedimentation rate — which is the speed at which your red blood cells settle to the bottom of a tube. An elevated rate can indicate inflammation. People with reactive arthritis often have an elevated sedimentation rate.
• Evidence of other problems. Rheumatoid factor is an antibody often found in the blood of people with rheumatoid arthritis. Anti-nuclear antibodies are proteins that are generally found in people who have connective tissue or autoimmune disorders. If you have reactive arthritis, you'll probably test negative on both of these tests.
• Genetic markers. The inherited HLA-B27 antigen increases your risk of reactive arthritis. Reactive arthritis can also occur in people without HLA-B27.

Joint fluid tests
Your doctor may use a needle to withdraw a sample of fluid from within an affected joint. This fluid will be tested for:

• Infections. Even though reactive arthritis is triggered by an infection in another part of your body, this infection doesn't affect your joints. If an infection is found in your joint fluid, you may have septic arthritis, which can result in severe joint damage.
• Crystals. If uric acid crystals are found in your joint fluid, you may have gout. This very painful type of arthritis often affects the big toe.

Tests of other body fluids
Your doctor may also check for infections in your:

• Urine
• Stool
• Genital secretions
• Throat mucus

Imaging tests
X-rays of your joints can indicate whether you have any of the characteristic signs of reactive arthritis, including soft tissue swelling, calcium deposits where tendons attach to bones and cartilage damage. X-rays can also rule out other types of arthritis.

The goal of treatment is to manage your symptoms and treat any underlying bacterial infections that may still be present.

Medications
Your doctor may prescribe an antibiotic to eliminate the bacterial infection that triggered your reactive arthritis if it's still detectable in your body. Which antibiotic you take depends on the bacteria that are present.

For your arthritis signs and symptoms, your doctor may recommend:

• Nonsteroidal anti-inflammatory drugs (NSAIDs). NSAIDs can relieve the inflammation and pain of reactive arthritis. Over-the-counter NSAIDs include ibuprofen (Advil, Motrin, others), naproxen (Aleve) and aspirin. Prescription NSAIDs, such as indomethacin (Indocin), may be more effective.
• Corticosteroids. These medications can suppress inflammation in your joints. Injection of a corticosteroid into affected joints can reduce inflammation and allow you to return to your normal activity level.
• Tumor necrosis factor (TNF) blockers. TNF is a cell protein (cytokine) that acts as an inflammatory agent in rheumatoid arthritis. TNF blockers target or block this protein and can help relieve pain and stiffness and improve tender or swollen joints. Doctors initially used TNF blockers to treat rheumatoid arthritis. Preliminary studies suggest that these medications, such as etanercept (Enbrel) and infliximab (Remicade), can decrease inflammation and relieve pain and stiffness for some people with reactive arthritis.

Physical therapy
Exercise can help people with arthritis improve joint function. Your doctor may have you meet with a physical therapist, who can provide you with specific exercises for your joints and muscles. Strengthening exercises are valuable for developing the muscles around your affected joints, which increases the joint's support. Performing range-of-motion exercises can increase your joints' flexibility and reduce stiffness.

Genetic factors appear to play a role in whether you're likely to develop reactive arthritis. Though you can't change your genetic makeup, you can reduce your exposure to the bacteria that may lead to reactive arthritis.

Make sure your food is stored at proper temperatures and is cooked properly. These steps can help you to avoid the many food-borne bacteria that can cause reactive arthritis, including salmonella, shigella, yersinia and campylobacter.

In addition, practice safe sex because preventing sexually transmitted diseases may lower your risk of developing reactive arthritis.