Tocilizumab is primarily used in the treatment of rheumatoid arthritis, particularly in cases where other treatments have not been effective. It works by blocking the activity of interleukin-6, a substance in the body that causes inflammation. This helps to reduce the symptoms of arthritis, such as swelling, pain, and joint stiffness.

In addition to rheumatoid arthritis, it is also used for treating systemic juvenile idiopathic arthritis and polyarticular juvenile idiopathic arthritis in children. Tocilizumab has shown effectiveness in managing cytokine release syndrome, a severe immune reaction that can occur in patients receiving certain types of immunotherapy, such as CAR-T cell therapy.

Furthermore, during the COVID-19 pandemic, tocilizumab was explored as a treatment option for severe cases where patients experienced an excessive immune response, leading to significant inflammation and organ damage. It has been used in hospitalized patients who require oxygen support or mechanical ventilation to help mitigate the inflammatory response associated with severe COVID-19.