The growth of cancer immunotherapy has led to an urgent need for a multispecialty approach to treating patients with advanced malignancies. Checkpoint inhibitor therapies cause a wide range of toxicities termed immune-related adverse events (irAEs) that can affect any organ system. Similar to the anti-tumor responses induced by these medications, irAEs represent an interruption of self-tolerance that results in T cell-driven cytotoxicity, the exact mechanisms of which are likely heterogeneous. This review describes the various immunologic pathways that may lead to irAEs along with the diverse clinical manifestations seen in clinical practice. Treatment based on the severity and specific organ involvement will also be discussed, along with an overview of current guidelines and potential challenges that arise with immunosuppressive medications.