Street Drug Additive Deadlier than Fentanyl Found in Las Vegas

That’s still only 1% of the samples analyzed by the Southern Nevada Health District (SNHD) since last September 2024 — samples taken from used drug paraphernalia as part of its routine surveillance program. And, so far, medetomidine has not been linked to any overdose deaths in Las Vegas.

Still, officials said the warning is necessary.

“This potent veterinary sedative — often mixed with opioids like fentanyl — can cause profound sedation and unpredictable effects, increasing the risk of severe harm or death,” SNHD spokesperson Cassius Lockett said in a statement. “We are urging residents and health care providers to stay informed, access community overdose prevention resources, and seek help immediately if they suspect exposure.”

Those other effects include low blood pressure, slowed heart rate, dizziness, extreme fatigue, shortness of breath, nausea, blurred vision and confusion.

First identified in illicit drug supplies on the East Coast several years ago, medetomidine is legitimately used to sedate rhinos, elephants, lions and other large mammals for medical procedures and relocation.

Deadlier Than Fentanyl

Because medetomidine is not approved for human use, there no clinical trials have established a precise lethal dose. Toxicology reports and veterinary data, however, indicate that even extremely small amounts can be fatal to humans — in some cases, smaller than the 2 mg often cited for fentanyl.

But it’s deadlier than fentanyl for another reason. Medetomidine is an alpha-2 adrenergic agonist rather than an opioid, so Narcan (naloxone) cannot reverse its effects. While fentanyl suppresses breathing, medetomidine suppresses the heart, creating a “perfect storm” of toxicity.

Medetomidine is also 100–200 times more potent than xylazine, the tranquilizer known as “tranq.”

If you suspect someone has been exposed to medetomidine, call 911 immediately. Administer naloxone if opioids may also be involved. (Though it won’t reverse medetomidine, it can still address any fentanyl present.) Keep the person breathing, monitor their airway, and stay with them until first responders arrive.