Reactive arthritis is joint pain and swelling triggered by an infection in another part of your body — most often your intestines, genitals or urinary tract.

Reactive arthritis usually targets your knees and the joints of your ankles and feet. Inflammation also can affect your eyes, skin and urethra.

Previously, reactive arthritis was sometimes called Reiter's syndrome, which was characterized by eye, urethra and joint inflammation.

Reactive arthritis isn't common. For most people, signs and symptoms come and go, eventually disappearing within 12 months.

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.

When to see a doctor

If you develop joint pain within a month of having diarrhea or a genital infection, contact your doctor.

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.

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 to help you avoid the many foodborne bacteria that can cause reactive arthritis, including salmonella, shigella, yersinia and campylobacter. Some sexually transmitted infections can trigger reactive arthritis. Using condoms might lower your risk.

During the physical exam, your doctor is likely to check your joints for signs and symptoms of inflammation, such as swelling, warmth and tenderness, and test range of motion in your spine and affected joints. Your doctor might also check your eyes for inflammation and your skin for rashes.

Blood tests

Your doctor might recommend that a sample of your blood be tested for:

• Evidence of past or current infection
• Signs of inflammation
• Antibodies associated with other types of arthritis
• A genetic marker linked to reactive arthritis

Joint fluid tests

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

• White blood cell count. An increased number of white blood cells might indicate inflammation or an infection.
• Infections. Bacteria in your joint fluid might indicate septic arthritis, which can result in severe joint damage.
• Crystals. Uric acid crystals in your joint fluid might indicate gout. This very painful type of arthritis often affects the big toe.

Imaging tests

X-rays of your low back, pelvis and joints can indicate whether you have any of the characteristic signs of reactive arthritis. X-rays can also rule out other types of arthritis.

The goal of treatment is to manage your symptoms and treat an infection that could still be present.

Medications

If your reactive arthritis was triggered by a bacterial infection, your doctor might prescribe an antibiotic if there is evidence of persistent infection. Which antibiotic you take depends on the bacteria that are present.

Other medications might include:

• Nonsteroidal anti-inflammatory drugs (NSAIDs). Prescription NSAIDs, such as indomethacin (Indocin), can relieve the inflammation and pain of reactive arthritis.
• Corticosteroids. Injection of a corticosteroid into affected joints can reduce inflammation and allow you to return to your normal activity level.
• Topical steroids. These might be used for skin rashes caused by reactive arthritis.
• Rheumatoid arthritis drugs. Limited evidence suggests that medications such as sulfasalazine (Azulfidine), methotrexate (Trexall) or etanercept (Enbrel) can relieve pain and stiffness for some people with reactive arthritis.

Physical therapy

A physical therapist can provide you with targeted exercises for your joints and muscles. Strengthening exercises develop the muscles around your affected joints, which increase the joint's support. Range-of-motion exercises can increase your joints' flexibility and reduce stiffness.

You'll likely start by seeing your primary care provider, who might refer you to a doctor who specializes in arthritis (rheumatologist) for further evaluation.

What you can do

When you make the appointment, ask if there's anything you need to do in advance, such as fasting before having a specific test. Make a list of:

• Your symptoms, including any that seem unrelated to the reason for your appointment
• Key personal information, including your and your family's medical history
• All medications, vitamins or other supplements you take, including doses
• Questions to ask the doctor

Take a family member or friend along, if possible, to help you remember the information you're given. For reactive arthritis, basic questions to ask your doctor include:

• What is likely causing my symptoms or condition?
• What are other possible causes?
• What tests do I need?
• What treatment approach do you recommend?
• How soon do you expect my symptoms to improve with treatment?
• Is there anything I can do now to help relieve my joint pain?
• Am I at risk of long-term complications from this condition?
• I have these other health conditions. How can I best manage them together?

Don't hesitate to ask other questions.

What to expect from your doctor

Your doctor is likely to ask you a number of questions, such as:

• When did your symptoms begin?
• Have they been continuous or occasional?
• How severe are your symptoms?
• What, if anything, seems to improve your symptoms?
• What, if anything, appears to worsen your symptoms?
• Have you had a recent infection?