Rheumatoid arthritis (RA) is a common chronic autoimmune inflammatory disease, primarily affecting the joints. Its activity is subject to exacerbations called flares. These RA flares are linked to cardiovascular, functional and radiological complications. The mechanisms behind these flares are still poorly understood. There is currently no reliable biomarker for the diagnosis of the flares. Diagnostic scores have been developed for research purposes but their application in clinical practice is not yet clear. The therapeutic approach includes acute treatment of the flare with corticosteroids and evaluation of the need for intensification of background therapy.