A black box warning (boxed warning) is the most serious safety warning required by the U.S. Food and Drug Administration (FDA) on a prescription drug label. It is enclosed in a bold-bordered black box at the beginning of the package insert and indicates that the drug carries a significant risk of serious or life-threatening adverse effects. Black box warnings are based on post-marketing surveillance data, clinical trial findings, or case reports that demonstrate a clear association between the medication and a specific severe adverse outcome. The FDA mandates these warnings when (1) an adverse reaction is so serious relative to the benefit that a prominent warning is necessary, (2) a serious adverse reaction can be prevented or reduced in frequency by proper patient selection or monitoring, or (3) the FDA has approved the drug with restrictions to ensure safe use (REMS — Risk Evaluation and Mitigation Strategy). For nurse practitioners with prescriptive authority, knowledge of high-yield black box warnings is essential for patient safety, informed consent, and medico-legal risk management. The NP must communicate the nature and magnitude of the...