In recent years, we have observed significant progress in cancer treatment associated with the development of immunotherapy. A programmed cell death 1 molecule (PD-1) on the surface of T lymphocytes may be stimulated via a specific PD-ligand 1 (PD-L1), which inhibits lymphocyte activation and leads to apoptosis. Some malignant cells are characterized by high PD-L1 expression. Nivolumab, an anti-PD-1 antibody, blocks the interaction between PD-1 and its ligands and inhibits the signaling pathway by preventing the tumor-derived PD-L1 from blocking T lymphocytes. In patients with non-small cell lung cancer (NSCLC), it is used either in monotherapy or in combination with other drugs. Immunotherapy is associated with the possibility of immune-related adverse effects (irAE) including endocrinopathies (3–23%). Thyroid disorders are the most common, with severity rarely exceeding grade 2. Hypophysitis, adrenal insufficiency and diabetes are possible complications which require immediate treatment. Individuals with autoimmune diseases diagnosed prior to immunotherapy are at risk of its exacerbation. In the management of patients receiving immunotherapy, evaluation of history of autoimmune diseases, awareness and early diagnosis of irAE are crucial and may affect treatment outcomes.