We report a case of a 30-year-old woman with a history of intravenous drug use, who presented to the emergency department with nausea, vomiting, agitation, and delirium. In order to protect her airway and to facilitate further evaluation, she received endotracheal intubation, but despite maximum pharmacologic sedation, she became increasingly tachycardic and hypertensive. A comprehensive blood toxicology panel revealed medetomidine, a sedative used in veterinary medicine and a known adulterant used in illicit fentanyl. While medetomidine has permeated the fentanyl supply in the middle Atlantic states, to our knowledge this is the first case reported in Rhode Island.