The potent animal sedative that’s replacing tranq in street drugs — and making fentanyl even more deadly
In the streets right now, there’s a new drug taking over—and it’s far more dangerous than people realize. A potent animal tranquilizer is quickly finding its way into the United States’ illegal drug market, sparking mass overdoses in places like Chicago and Philadelphia.
The substance was first spotted in New York last year, sending public‑health officials into high alert. Although its effects can resemble opioids such as fentanyl, it won’t be stopped by the usual overdose‑reversal drugs.
The drug, medetomidine, is a veterinary sedative that calms muscles and eases pain during surgery by slowing the brain’s release of adrenaline. It’s similar to xylazine—commonly known on the street as “tranq”—but experts say medetomidine can be up to 20 times more potent, making even small amounts highly addictive.
What makes it especially concerning is how easy it is to acquire. The compound is inexpensive and readily available from online vendors that sell veterinary supplies and research chemicals. Cartels and local dealers have begun mixing it into their product lines “to increase addiction, expand their customer base, and boost profits,” says Frank A.
Tarentino III, a special agent with the DEA’s New York Division. “Adding a more powerful fentanyl‑like compound—whether it’s carfentanil or medetomidine—intensifies the risk of catastrophic overdoses,” he added.
Medetomidine first entered the U.S. illicit drug supply in 2021. By July 2024 it had been detected in drug samples and bodily fluids from users across at least 18 states and Washington, D.C. Researchers believe the coverage has probably continued to widen, and the resulting fatalities have likely risen as well.
When people take medetomidine, it slows their heart rate and produces deep sedation that can linger for hours or even induce coma. Common side effects include dizziness, extreme fatigue, shortness of breath, nausea, blurred vision, and confusion.
The bigger problem emerges when the drug finally wears off: withdrawal can be so intense that many patients need intensive‑care monitoring. Symptoms can involve dangerously high heart rate and blood pressure—capable of causing brain damage—uncontrolled vomiting, tremors, and profuse sweating.
Dr. Daniel del Portal, an emergency‑room physician and hospital administrator at Temple Health in Philadelphia, told The New York Times that the city’s ICUs have been overwhelmed. He remarked that medetomidine is appearing more often than xylazine in Philadelphia’s drug supply, a trend that medical staff, EMTs, and outreach teams now refer to as “the withdrawal crisis.” In just the first nine months of 2025, Philadelphia hospitals logged 7,252 emergency‑department visits for withdrawal, compared with 2,787 for the entire year of 2023.
And it’s not just withdrawal that’s scary. Overdose victims on medetomidine typically don’t respond to opioid‑reverse agents such as naloxone – commonly sold under the brand name “Narcan” – in the same way that fentanyl patients do. When someone overdoses on a mix of opioids and medetomidine, naloxone can help restore breathing but won’t counteract the sedative lull, leaving patients unconscious.
Dr. Kory London, an associate professor of emergency medicine at Thomas Jefferson University, and Dr. Karen Alexander, an adjunct nursing professor, wrote in The Conversation that “after patients begin to breathe normally, additional doses of naloxone do not seem to help and can even trigger opioid withdrawal.”
They advise using naloxone when signs of opioid overdose are evident—deep sedation, shallow or absent breathing, pinpoint pupils—but caution against giving more when breathing improves but consciousness remains delayed.
If a suspected medetomidine overdose does not respond to naloxone, health experts recommend performing rescue breathing (mouth‑to‑mouth ventilation) while awaiting emergency responders. The drug’s rise has added a new layer of complexity to an already difficult overdose landscape, forcing providers to adjust their protocols as the city’s drug‑use crisis evolves.
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