Why does reactive arthritis cause joint pain?

Symptoms can begin after an infection, often affecting the bowel or urinary tract, even when the original infection has settled. The immune system remains active and may inflame the joint lining, tendons, or places where tendons attach to bone. This can lead to aching, warmth, swelling, and stiffness, often in a knee, ankle, foot, or toe. Joint Pain is a common presentation of Reactive Arthritis. Some people also develop eye redness, pain when passing urine, or skin changes.

Arrange a medical review if joint pain follows a recent infection or comes with swelling and reduced movement. Tell the clinician about recent diarrhoea, genital or urinary symptoms, eye symptoms, medicines, and any joints involved. Resting an acutely painful joint briefly may help, while gentle movement within comfort can limit stiffness. A clinician can assess for infection, inflammation, and other explanations for the pain.

Seek urgent care for a hot, very swollen joint with fever or feeling unwell, because joint infection needs rapid assessment. Get same-day advice for a painful red eye, light sensitivity, or blurred vision, as eye inflammation can require prompt treatment. Sudden inability to bear weight also needs timely review.

Ask whether your recent illness could be relevant, which joints and tendons are inflamed, whether tests are needed, and how to protect mobility while symptoms are active.