Cytokine release syndrome (CRS) is an acute systemic inflammatory syndrome characterized by fever and multiple organ dysfunction that is associated with chimeric antigen receptor (CAR)-T cell therapy, therapeutic antibodies, and haploidentical allogeneic transplantation. Immune effector cell-associated neurotoxicity syndrome (ICANS) is a neuropsychiatric syndrome that can occur in some patients who are treated with immunotherapy and may or may not accompany CRS.