Background: Angiotensin-converting enzyme (ACE) inhibitor-induced angioedema is a rare, albeit serious emergency that can result in airway compromise and potentially death if not treated promptly. Currently, there are no agents approved by the Food and Drug Administration to target ACE inhibitor angioedema and to prevent intubation. C1 inhibitors are approved for hereditary angioedema but may show promise in alleviating inflammation associated with ACE inhibitor angioedema. Case Report: A 41-year-old man presented to the emergency department with swelling of his lips a few days after starting lisinopril for hypertension. Despite receiving diphenhydramine, ranitidine, and methylprednisolone, the swelling progressed to the patient's tongue. AC1 inhibitor was ordered in an effort to prevent intubation. Before the arrival of the medication, the patient was intubated emergently for airway protection. After receipt of the C1 inhibitor, the swelling dramatically improved, and the patient was successfully extubated after less than 18 hours from presentation. Why Should an Emergency Physician Be Aware of This?: This case illustrates a potential role for C1 inhibitors in the emergency setting for treating drug-induced angioedema, which may prevent or minimize mechanical ventilation time. (C) 2015 Elsevier Inc.