There’s a new beast on the streets — and it’s nothing to bark at.
A powerful animal tranquilizer is increasingly saturating the US drug supply, fueling mass overdose outbreaks in hotspots like Chicago and Philadelphia.
It was detected in New York last year, setting off alarm bells among public health officials. They warn that while its effects can mimic opioids such as fentanyl, there’s a dangerous catch: It doesn’t respond to conventional overdose-reversal treatments.
The drug, medetomidine, is a sedative used by veterinarians to relax muscles and relieve pain, often during surgery. It works by slowing the release of adrenaline in the brain and body.
It’s similar to xylazine, or tranq — a veterinary painkiller and muscle relaxant commonly cut into street drugs since about 2020 — but it’s even more dangerous. Experts say it can be up to 20 times more potent, meaning small amounts can be highly addictive.
Adding to the threat, medetomidine is cheap and easy to obtain, readily available online through suppliers of veterinary medicines and research chemicals.
Cartels and street-level dealers “are mixing these lethal synthetics into their drug supply … to increase addiction, to increase their customer base, to make more money,” Frank A. Tarentino III, special agent in charge of the Drug Enforcement Agency’s New York Division, told The Post last year.
“Then you introduce a more powerful fentanyl like carfentanil, or medetomidine, which is more powerful and more dangerous than xylazine, then you’re talking about even greater catastrophic overdoses and poisonings than we’re already seeing.”
Medetomidine was first detected in the US illicit drug supply in 2021. By July 2024, it had been found in drug samples and biospecimens of people using illicit opioids in at least 18 states and Washington, DC.
Since then, experts say the drug’s footprint has almost certainly expanded — and so has its body count.
When people use medetomidine, it slows their heart rate and causes heavy sedation that can last for hours and even lead to coma. Users often experience side effects such as dizziness, extreme fatigue, shortness of breath, nausea, blurred vision and confusion.
But the real nightmare begins when the drug wears off.
Withdrawal can be so severe that many patients require intensive care. Life-threatening symptoms include dangerously high spikes in heart rate and blood pressure — high enough to cause brain damage — along with uncontrollable vomiting, tremors and profuse sweating.
“Our ICUs have been overwhelmed,” Dr. Daniel del Portal, an emergency room physician and hospital administrator at Temple Health in Philadelphia, told The New York Times.
Medetomidine is now showing up more frequently than xylazine in the city’s drug supply, a surge that del Portal said doctors, emergency medical workers and outreach teams have come to call “the withdrawal crisis.”
In the first nine months of 2025 alone, Philadelphia hospitals recorded 7,252 emergency department visits for withdrawal, compared with 2,787 in all of 2023, according to city public health records.
Withdrawals aren’t the only concern.
When people overdose on medetomidine, they often don’t respond to opioid-reversal drugs like naloxone — commonly known as Narcan — the way fentanyl users do, making overdoses far harder to reverse.
In cases where patients overdose on a mix of opioids and medetomidine, naloxone can help restart breathing but does not counteract the sedative effects of medetomidine. As a result, patients may remain unconscious.
“From our clinical experience, after patients start to breathe normally, providing additional doses of naloxone does not seem to help and even risks prompting opioid withdrawal symptoms,” Dr. Kory London, an associate professor of emergency medicine at Thomas Jefferson University, and Dr. Karen Alexander, an adjunct professor at the school’s College of Nursing, wrote in The Conversation.
“Naloxone is still recommended for a person showing signs of opioid overdose — such as excess sedation, shallow or absent breathing and small pupils,” they added. “But if the patient starts breathing but does not immediately wake up, additional doses of naloxone should be avoided.”
If a suspected overdose victim doesn’t respond to naloxone because of medetomidine, health officials recommend “rescue breathing,” or mouth-to-mouth resuscitation, while waiting for emergency responders to arrive.
