Rheumatoid arthritis (RA) is a chronic inflammatory disease that primarily affects the joints, but also many other organs such as the skin, nerves, heart and lungs. It affects up to 2% of the world's population, with women being affected 3 times more frequently than men. Symptoms usually begin between the ages of 30 and 50. The etiology of the disease is the result of the interaction of genetic and environmental factors. The HLA-DRB1 alleles have the strongest individual genetic association with RA, while smoking is the most significant known environmental risk factor. The main feature of rheumatoid arthritis is synovitis, which leads to cartilage and bone damage. The clinical picture is characterized by symmetric polyarthritis, which manifests as morning stiffness, pain, and joint swelling. A detailed clinical examination, laboratory tests, and imaging radiological examinations are used to make the diagnosis of rheumatoid arthritis. Treatment is based on symptomatic relief and the use of disease-modifying antirheumatic drugs (DMARDs). Symptomatic treatment consists primarily of nonsteroidal antirheumatic drugs (NSAIDs) and glucocorticoids (GCs), while methotrexate is used as the first line of therapy. Janus kinase inhibitors (JAK) are the newest group of drugs for the treatment of rheumatoid arthritis. They are the first oral option for the treatment of RA comparable to existing biologic disease-modifying antirheumatic drugs (bDMARDs), which are administered subcutaneously or intravenously. JAK inhibitors reduce inflammation by inhibiting intracellular signaling pathways in inflammatory cells.