CDC issues warning as Narcan resistant animal tranquilizer 100-200 times stronger than xylazine sees spike in northeast

MASSACHUSETTS/RHODE ISLAND/NEW YORK/PENNSYLVANIA – The CDC is issuing a health warning that should get the attention of those in the northeast.

Medetomidine, also known as “rhino tranq,” “mede,” or “dex”, is a powerful synthetic alpha-2 adrenergic agonist used as a sedative and analgesic in veterinary medicine, primarily for dogs and other animals. It is far more potent than xylazine (“tranq”), often described as 100–200 times stronger, and produces profound, prolonged sedation and is not approved for humans.

In the illicit drug supply, medetomidine is being mixed almost exclusively with fentanyl (detected in 98% of positive samples). It is believed to be synthesized in clandestine labs rather than diverted from veterinary sources. It is added to enhance or prolong the sedative effects of fentanyl, but users rarely know it is present.

Medetomidine has spread rapidly since mid-2024, with a dramatic surge in 2025–2026.

According to the latest CDC Health Advisory issued this week, detections are now heavily concentrated in the Northeast (52% of all NFLIS forensic reports nationwide), followed by the Midwest. Reports to the National Forensic Laboratory Information System (NFLIS) skyrocketed: a 950% increase from 2023 to 2024, then another 215% jump in 2025. Wastewater testing and drug-checking programs in Northeastern states (including Massachusetts, Rhode Island, and others) have shown consistent weekly detections since late 2025.

Local health departments in Rhode Island and Massachusetts have issued overdose spike alerts in recent weeks, with non-fatal overdoses rising notably in March 2026. Similar increases have been reported in New York, Pennsylvania, and parts of New England.

Because it is not an opioid, medetomidine does not respond to naloxone (Narcan) on its own, however, naloxone should still always be given because it is almost always combined with fentanyl.

Key effects include:

• Extremely deep, prolonged sedation (often described as “zombie-like” or coma-like states)
• Severe bradycardia (heart rate can drop as low as 32 bpm)
• Hypotension (dangerously low blood pressure)
• Respiratory depression
• Higher risk of overdose and harder-to-reverse effects compared to fentanyl alone

Withdrawal from medetomidine is particularly severe, often worse than typical opioid withdrawal, and can include rebound hypertension, agitation, vomiting, and symptoms requiring ICU-level care.

Public health officials are urging people who use drugs to test their supply when possible, carry naloxone anyway, avoid using alone, and seek medical help immediately for any suspected overdose. The situation is still evolving, but medetomidine is currently considered one of the most concerning new adulterants in the Northeast opioid supply. If you or someone you know uses opioids, the best resources are local harm-reduction programs, syringe service providers, or the SAMHSA National Helpline (1-800-662-HELP). Stay safe.