Deadly ‘Rhino Tranquilizer’ Spreading in the US, Mixed with Fentanyl Increasing Risk of Fatalities
News Summary
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- US health officials have issued a high alert after detecting a new deadly substance called medetomidine being mixed with fentanyl.
- Medetomidine was found in only 247 samples in 2023, soaring to 8,233 samples in 2025 — a rise of over 3,000%.
- More than 175 overdoses linked to medetomidine were reported in Chicago, with 16 hospitalizations and one death.
US health authorities and the White House have raised a high alert over the discovery of a new and extremely dangerous substance in the illegal drug supply.
A drug called medetomidine, typically used by veterinarians to sedate large animals, is now being mixed with the lethal opioid fentanyl and sold on the streets.
On the street, it is known by nicknames such as “Rhino Tranquilizer,” “Mede,” or “Dex.” According to the US Centers for Disease Control and Prevention (CDC), its use is increasing at an alarming rate.
In 2023, medetomidine was detected in only 247 samples. This number jumped to 2,616 samples in 2024 and further soared to 8,233 samples in 2025 – indicating more than a 3,000% increase.
Almost 98% of the tested samples were found to be mixed with fentanyl. So far, this substance has been confirmed in wastewater and overdose incidents across 18 US states and Washington, D.C.
Dr. Adam Sioli from Pennsylvania stated that medetomidine is difficult to detect through routine toxicology screenings, complicating treatment for patients admitted to hospitals.
In a notable incident in Chicago, over 175 overdose cases involved medetomidine, resulting in 16 hospital admissions and one fatality.
Officials are urging drug users and healthcare providers to stay vigilant about this emerging and evolving threat.
