Joint pain and inflammation can occur in response to an infection, usually of the genitourinary or gastrointestinal tract.
Tendon inflammation, rashes, and red eye are also common.
The diagnosis is based on symptoms.
Nonsteroidal anti-inflammatory drugs, sulfasalazine, and sometimes drugs that suppress the immune system (such as azathioprine or methotrexate) may help treat the symptoms.
Reactive arthritis is so called because the joint inflammation seems to be a reaction to an infection originating in the digestive (gastrointestinal) tract or the genitals or urinary (genitourinary) organs.
There are two common forms of reactive arthritis:
One form occurs in people with sexually transmitted diseases, such as a chlamydial infection. This form occurs most often in men aged 20 to 40.
Most people who have these infections do not develop reactive arthritis. People who develop reactive arthritis after exposure to these infections seem to have a genetic predisposition to this type of reaction, related in part to the same HLA-B27 gene found in people who have ankylosing spondylitis. There is some evidence that the chlamydia bacteria and possibly other bacteria actually spread to the joints, but the roles of the infection and the immune reaction to it are not clear.
Reactive arthritis may be accompanied by inflammation of the conjunctiva and the mucous membranes (such as those of the mouth and genitals) and by a distinctive rash. This form of reactive arthritis previously was called Reiter syndrome.
In reactive arthritis, joint pain and inflammation may be mild or severe. Several joints are usually affected at once—especially the knees, toe joints, and areas where tendons are attached to bones, such as at the heels. Often, the large joints of the lower limbs are affected the most. Reactive arthritis often involves joints less symmetrically than rheumatoid arthritis. Tendons may be inflamed and painful. Back pain may occur, usually when the disease is severe. Other symptoms include a low-grade fever, weight loss, and excessive fatigue.
Inflammation of the urethra (urethritis—the channel that carries urine from the bladder to the outside of the body) can develop, usually about 7 to 14 days after an infection (after sexual contact or sometimes after diarrhea).
In men, inflammation of the urethra causes moderate pain and a discharge from the penis or a rash of small and usually painless sores on the glans of the penis (balanitis circinata). The prostate gland may be inflamed and painful.
In women, the genital and urinary symptoms, if any occur, are usually mild, consisting of a slight vaginal discharge or uncomfortable urination.
The conjunctiva (the membrane that lines the eyelid and covers the eyeball) can become red and inflamed, causing itching or burning, sensitivity to light, and sometimes pain and excessive tearing.
Small and usually painless or sometimes tender sores can develop in the mouth and on the tongue. Occasionally, a distinctive rash of hard, thickened spots may develop on the skin, especially of the palms and soles and around the nails (keratoderma blennorrhagicum).
Rarely, heart and blood vessel complications (such as inflammation of the aorta), inflammation of the membranes covering the lungs, dysfunction of the aortic valve, and brain and spinal cord symptoms or peripheral nervous system (which includes all the nerves outside the brain and spinal cord) symptoms develop.
The combination of joint symptoms and a preceding infection, particularly if the person has genital, urinary, skin, and eye symptoms, leads a doctor to suspect reactive arthritis. Because these symptoms may not appear simultaneously, the disease may not be diagnosed for several months.
No simple laboratory tests are available to confirm the diagnosis of reactive arthritis, but x-rays are sometimes done to assess the status of joints. Tests may be done to exclude other disorders that can cause similar symptoms.
In most people, the initial symptoms of reactive arthritis disappear in 3 or 4 months, but up to 50% of people have recurring joint inflammation or other symptoms over several years.
Deformities of the joints, spine, and joint between the spine and the hip bone (sacroiliac joint) may develop if the symptoms persist or recur frequently. Some people who have reactive arthritis become permanently disabled.
When reactive arthritis is caused by infection of the genitals or urinary tract, antibiotics are given, but this treatment does not always relieve the arthritis and its optimal duration is not known.
Joint inflammation is usually treated with a nonsteroidal anti-inflammatory drug (NSAID). Sulfasalazine or drugs that suppress the immune system (such as azathioprine or methotrexate) may be used, as in rheumatoid arthritis.
Corticosteroids can also be injected into a severely inflamed joint or inflamed tendons to relieve symptoms.
Physical therapy is helpful in maintaining joint mobility during the recovery phase.
Conjunctivitis and skin sores do not usually need to be treated, although severe eye inflammation (uveitis) may require corticosteroid and dilating eye drops.