Immune checkpoint inhibitors (ICPIs) and chimeric antigen receptor (CAR) T-cell therapy are two main promising methods of immunotherapy, which have become increasingly important in cancer treatment. After the wider application of these medicine in clinic, a range of immune related adverse events (irAEs) covering almost any system arouse the concern for being randomness and unpredictability. Even if most adverse events are mild and controllable after thoughtful management, the occurrence of life-threatening toxicities should not be ignored because of the insidious and atypical symptoms, which makes the early diagnosis even more challenging. In this review, a brief introduction of immunotherapy and mechanisms underlying irAEs is involved. We mainly focus on the early diagnostic method and recommended management of toxicities of different systems separately, and consequently maximized effectiveness of immunotherapy can be achieved.