Reactive arthritis

Reactive arthritis is an inflammatory reaction in the joints triggered by an infection elsewhere, usually in the gut or the urinary and genital tract. The immune system, primed by the infection, mistakenly causes inflammation in the joints, tendons and sometimes the eyes, even though the joints themselves are not infected.

Common triggers include bowel infections such as salmonella or campylobacter, and sexually transmitted infections such as chlamydia.

It tends to affect younger adults, and is more common in men after a urinary trigger. Carrying the HLA-B27 gene makes it more likely and links it to related conditions such as axial spondyloarthritis and psoriatic arthritis.

Reactive arthritis typically comes on after an infection. Features may include:

• Pain and swelling, often in the larger joints of the legs, such as the knees or ankles
• Swelling of a whole finger or toe, or pain where tendons attach to bone
• Sometimes eye inflammation or urinary symptoms
• A history of a gut or urinary infection in the preceding weeks

Diagnosis is based on the pattern of symptoms, the recent history of infection, an examination and tests to look for inflammation and exclude other causes such as gout or other forms of arthritis. Confirming the picture helps guide treatment and offer reassurance about the likely course.

Ultrasound can help assess inflammation in the joints and tendons. Dr Borukhson uses point-of-care ultrasound during the consultation, so this can often be done in the same visit. You can read more on the ultrasound clinic page.

Treatment focuses on settling the joint inflammation and relieving symptoms while the condition runs its course. Anti-inflammatory measures are often the mainstay, and where a single joint is troublesome an ultrasound-guided injection may help.

In the minority whose symptoms persist, relapse or become long-standing, longer-term treatment is added to bring the inflammation under control. Standard disease-modifying anti-rheumatic drugs (DMARDs) such as sulfasalazine or methotrexate, which need regular blood-test monitoring, are used when the arthritis is ongoing or affects several joints. Where it stays active despite these, biologic medicines that target the immune signals driving inflammation, such as anti-TNF therapies, can be effective, with screening carried out before they begin. The plan is agreed with you and reviewed over time, as most cases settle in the end.

While the inflammation settles, gentle movement helps far more than complete rest. Keeping affected joints moving within comfort, with simple range-of-movement exercises, maintains flexibility and reduces stiffness, and a physiotherapist can guide you.

Pace activity, rest a flared joint when it is hot, then build back gradually. Some people find an ice pack eases a swollen knee or ankle.

If a gut or genital infection triggered it, completing any prescribed treatment, and ensuring a sexual partner is treated where relevant, helps prevent a further episode.

Keeping follow-up appointments matters even once you feel better, as symptoms can occasionally return or persist and are more easily managed when reviewed early.

A hot, very painful, swollen joint that comes on rapidly, especially with fever or feeling unwell, needs same-day medical assessment, as a joint infection has to be ruled out urgently and cannot wait.

Seek prompt advice if you develop:

• A red, painful or light-sensitive eye, or sudden change in vision, which needs urgent same-day eye review
• New or worsening back pain with numbness, leg weakness, or loss of bladder or bowel control

Arrange a routine review if joint pain and swelling persist beyond a few weeks, keep returning, spread to new joints, or are not settling with the measures agreed with you. Ongoing inflammation is more easily controlled when it is reassessed early rather than left.

While reactive arthritis often improves with time, assessment confirms the diagnosis, excludes other causes of a hot, swollen joint, and ensures symptoms are managed well. If you have developed joint swelling after a recent infection, a specialist review can help.

How is reactive arthritis diagnosed?

There is no single test that confirms reactive arthritis, so the diagnosis is based on the pattern of joint symptoms, a recent history of a gut or urinary infection, an examination and blood tests. The tests also help exclude other causes of a hot, swollen joint, such as gout or other forms of arthritis. During the consultation Dr Borukhson can use point-of-care ultrasound to look for inflammation in the joints and tendons, often in the same visit, which helps build an accurate picture sooner.

Will reactive arthritis go away, and is it curable?

In many people reactive arthritis settles over time as the inflammation calms down, and a good number recover fully. A smaller number find that symptoms persist, come back or become long-standing, and in that situation longer-term treatment can bring the inflammation under control. A specialist review helps confirm the likely course for you and ensures symptoms are managed well along the way.

Is reactive arthritis serious?

For most people reactive arthritis is uncomfortable but tends to improve, rather than being dangerous. It is still worth having it assessed, because a hot, swollen joint can have other causes that need different treatment, and inflammation that drags on is better managed early. Eye symptoms or a very painful, hot joint should prompt an early review.

Do I need surgery for reactive arthritis?

Reactive arthritis is not usually a surgical condition. Treatment focuses on settling the inflammation and relieving symptoms with anti-inflammatory measures, and where one joint is particularly troublesome an ultrasound-guided injection may help. If symptoms persist or affect several joints, medicines that calm the immune response can be added, with the plan agreed with you and reviewed over time.