Adrenal crisis is a life-threatening endocrine emergency that can progress within hours despite a prior diagnosis and maintenance therapy. We describe a fatal influenza-triggered adrenal crisis in two patients: a child with panhypopituitarism and an adult with prior pituitary surgery, both presenting in cardiac arrest. Despite resuscitation and intravenous hydrocortisone, a fatal hypoxic-ischemic injury or multiorgan failure occurred. These cases highlight the fulminant course of an adrenal crisis and underscore the importance of early recognition, clinician awareness, prompt parenteral hydrocortisone administration, and reinforcement of education for patients, caregivers, and healthcare providers to improve preparedness and prevent avoidable deaths.