The Centers for Disease Control and Prevention and the White House Office of National Drug Control Policy issued a health advisory about medetomidine being detected in fentanyl, raising serious concerns about overdose risk and treatment complications. Also known as “rhino tranq,” “mede,” or “dex,” medetomidine is a veterinary sedative that causes severe, prolonged sedation and acts on the nervous system similarly to other veterinary sedatives like xylazine.
Surveillance data shows a dramatic increase in detections. In 2023, there were 247 incidences of medetomidine detected in drug samples, which rose to 2,616 in 2024 and 8,233 in 2025—a more than 3,000% increase. Forensic drug reports showed that about 98% of medetomidine-positive samples also contained fentanyl. The drug has been detected in at least 18 states and Washington, D.C., with concentration in the Northeast and Midwest regions.
A critical concern is that naloxone (Narcan), the standard overdose reversal medication, does not counteract medetomidine’s sedative effects. While naloxone remains essential for reversing opioid-induced respiratory depression, it does not address the sedative effects of medetomidine. Additionally, medetomidine is not routinely detected on standard toxicology screens, increasing the risk of under-recognition.
Initial effects of medetomidine include deep sedation or decreased consciousness, bradycardia (slow heart rate), hypotension (low blood pressure), and respiratory depression, especially when combined with fentanyl. Withdrawal symptoms typically begin a few hours after use, can be severe and rapid, and peak at about 18-36 hours. These include rising blood pressure, tachycardia, agitation, nausea and vomiting, and can progress to severe hypertension, altered mental status, and possible cardiac or neurologic complications.
In a May 2024 example, medetomidine in the illegal opioid supply was linked to a cluster of overdoses in Chicago potentially exceeding 175, with at least 16 people hospitalized and one death. Management of severe cases requires ICU-level monitoring and care.
This article is an AI-assisted summary. All facts and figures are drawn from the original report: https://www.foxnews.com/health/fatal-drug-combination-sparks-alert-rhino-tranq-spreads-across-us