Reactive arthritis is a rubric replacing the previously used name of infectious-allergic arthritis.
In reactive arthritis, the diagnosis should include the “source” of the disease. Typically, these are various infectious processes: nasopharyngeal, uregenital, enterocolitic, viral, etc.
The main difference between reactive arthritis and rheumatoid arthritis is their acute or subacute course without a tendency to deformities of the joints.
More often they are observed at a young age, clearly associated with an infectious factor. The reaction of Vaaler — Rosa would be negative in this case.
In acute allergic diseases, arthritis has an acute course against the background of the clinic of the underlying disease (serum sickness, erythema nodosum, drug disease, etc.) and no major difficulties in the differential diagnosis with roar arthritis.