Nivolumab is used to treat several different types of cancers. Although it is generally considered to be effective and well-tolerated, it has been associated with adverse effects requiring discontinuation of treatment, like many other drugs used for cancer. A 70-year-old male was switched from sunitinib to nivolumab for renal cell carcinoma. The patient developed persistent hypothyroidism, onycholysis, and pneumonitis at nivolumab cycle 6, 10, and 11, respectively. Using the Naranjo causality method, the likelihood of causality was deemed “probable” for pneumonitis and hypothyroidism and “possible” for onycholysis. Nivolumab was eventually discontinued due to disease progression, rather than safety concerns. Eudravigilance, the European pharmacovigilance database, was searched for all nivolumab-related individual case safety reports from Malta, up to September 4, 2023. Six reports were identified in Malta, although the 3 events identified in this case report were not reported, suggesting under-reporting in Malta. This case report identified an uncommon nivolumab adverse drug reaction (ADR), onycholysis and showed how, despite the occurrence of 3 ADRs, it was its lack of efficacy rather than its safety which led to its discontinuation in this particular patient.