A new and concerning substance is making its way through the U.S. drug scene, and it’s not something to overlook.
Powerful animal tranquilizers are becoming more prevalent in the drug supply across the U.S., leading to spikes in overdose cases in cities like Chicago and Philadelphia.
Public health officials were alarmed when this drug was identified in New York last year. They are concerned because, although its effects can mirror those of opioids like fentanyl, it does not respond to traditional overdose reversal methods.
The substance medetomidine is used by vets as a sedative to ease muscle tension and pain during veterinary procedures. It works by decreasing adrenaline in the brain and body.
This drug is similar to xylazine, often called Trunk, a painkiller that emerged as a street substance around 2020. However, medetomidine is considered even more hazardous. Experts emphasize that it can be up to 20 times more powerful, and even minor quantities can lead to addiction.
Compounding the issue, medetomidine is inexpensive and can be easily purchased online from suppliers of veterinary drugs and research chemicals.
Frank A. Tarentino III, the special agent in charge of the Drug Enforcement Administration’s New York division, mentioned that drug cartels and street dealers are adding these synthetic compounds into the market to boost addiction rates and broaden their customer base to increase profits.
He added, “When you introduce stronger fentanyls, like carfentanil and medetomidine, the risks of overdoses and poisonings rise dramatically.”
By July 2024, medetomidine was first detected in the U.S. illegal drug supply, appearing in drug samples and biological specimens from at least 18 states and Washington D.C.
Since then, experts suggest that its presence has likely grown, resulting in more fatalities.
Medetomidine slows heart rates and causes deep sedation lasting several hours, at times leading to comas. Users report side effects like dizziness, fatigue, shortness of breath, nausea, blurred vision, and confusion.
However, the most severe issues occur once the drug begins to wear off.
Withdrawal symptoms can be so intense that many individuals require extensive care. Serious symptoms can involve dangerously high heart rates and blood pressure, which could lead to brain damage, as well as severe vomiting, shaking, and sweating.
“Our ICUs are overwhelmed,” noted Dr. Daniel Del Portal, an emergency room physician at Temple Health in Philadelphia, who spoke with the New York Times.
He pointed out that medetomidine is now being found more commonly in the local drug supply than xylazine, prompting health workers to label the situation a “withdrawal crisis.”
In Philadelphia, emergency room visits related to this drug surged, with 7,252 visits recorded in the first nine months of 2025, compared to just 2,787 in all of 2023, according to public health data.
It’s not solely the withdrawal that poses a threat.
Overdoses involving medetomidine often do not respond to reversal drugs like naloxone (commonly known as Narcan), which complicates overdose responses considerably. In cases where a person overdoses on both opioids and medetomidine, naloxone might help restore breathing, but it cannot counteract the sedation caused by medetomidine, sometimes leaving the patient unconscious.
“In our clinical experience, more naloxone doses after restoring normal breathing don’t seem effective and could even lead to withdrawal symptoms,” explained Dr. Cory London from Thomas Jefferson University.
He and Dr. Karen Alexander noted that while naloxone is still advised for signs of opioid overdose, additional doses should be avoided if patients are breathing but don’t regain consciousness quickly.
If someone is suspected of overdosing on medetomidine and does not react to naloxone, health officials suggest performing “rescue breathing” while awaiting paramedics.
