With the implementation of immunotherapy, a completely new, broad spectrum of side effects has emerged in oncology-the immune-related adverse events (irAEs). Their management differs greatly from that of classic cytotoxic side effects and is based primarily on corticosteroids, immunomodulatory agents, and treatment interruptions. Whereas some events are low grade and reversible, others can be severe and lead to permanent disorders or even death. Therefore, early recognition and treatment in the context of interdisciplinary side effects management is critical for patients' safety, prognosis, and quality of life.