RESUMEN
A 20-year-old male was admitted to our hospital due to a cosmetic problem of gynecomastia. He received a surgical resection of subcutaneous fat through an incision in the periareolar area under general anesthesia. On the postoperative fifth day, he complained of intraoral pain due to an oral ulcer. He was prescribed benoxinate at 4 mL (12 mg) for use by gargling, but instead he injected it intravenously by himself. He experienced severe tremors in the extremities, chest discomfort, and palpitation immediately after injection, and sinus tachycardia was noted on the electrocardiogram. We managed his symptoms by hydration with normal saline and oxygen supplementation. Seven hours later, his symptoms had subsided, and no further complications were observed.