The Supply Changed Again. The Rules You Built to Stay Alive Don't Work the Same Way Anymore.

The knowledge spreads the same way the drug does — faster through some communities than others, unevenly, without coordination, mostly through the same informal networks that move everything else in a world that has no formal infrastructure for this.

By 2022, most people who injected drugs in Philadelphia had heard about xylazine. Not from a CDC alert — the first federal health advisory on xylazine in the opioid supply came years after the drug was already killing people in the Northeast — but from each other. Don’t use alone. If you fall out, the person with you needs to know the naloxone doesn’t reverse the xylazine component. Watch for the wounds, because xylazine causes tissue necrosis and the wounds look different and need different wound care. Give extra doses and wait longer for the naloxone to work. This knowledge, assembled without public health guidance, without federal support, through networks of people who use drugs sharing what they had learned, was real and functional and saved lives.

Now medetomidine is in the supply. And most of the people who know about it learned about it from someone who knew someone who survived it.

Medetomidine has not replaced xylazine in the drug supply — it has joined it, and the harm reduction strategies people developed over five years of xylazine are no longer sufficient. The communities doing the adaptation work have less support now than they had when they were learning xylazine, because the federal government just banned funding for the organizations that help them do it.

What Medetomidine Is and Why It Matters That You Haven’t Heard of It

Medetomidine is a veterinary sedative — it is what veterinarians use to sedate dogs and cats for surgery. It is an alpha-2 adrenergic agonist, which, translated into terms that matter for overdose: it works on the same category of receptor as xylazine, produces the same kind of sedation that is not reversed by naloxone, and causes the same kind of profound physiological depression that can kill you through mechanisms entirely separate from the opioids it is mixed with.

Translated more simply: you can give naloxone and reverse the fentanyl component of an overdose and the person can still die because the medetomidine component is still active and their blood pressure has crashed and they are still unconscious. The CDC’s April 2026 Health Alert Network advisory on medetomidine — the first federal HAN alert ever issued for an unscheduled, uncontrolled drug — described the withdrawal as “more severe and faster-onset than xylazine withdrawal,” beginning within hours of last use and peaking at 18 to 36 hours with profound tachycardia, hypertension, and vomiting. And medetomidine is estimated to be up to 300 times more potent than xylazine.

The scale of its presence in the drug supply: the CDC HAN advisory reported 247 National Forensic Laboratory Information System (NFLIS) reports for medetomidine in 2023. By 2024, that number was 2,616 — a 950% increase. By 2025, it had risen to 8,233 — a further 215% increase. Medetomidine is not an emerging threat in the way that phrase is usually used, as though emergence is theoretical. It is already in the supply in dozens of states. People are already dying with it in their system. Most of them don’t know it was there.

The Culture of the Rapidly Changing Supply

There is a phrase that gets used in harm reduction circles: the supply has changed again. It is the signal for a specific kind of community recalibration — a moment when the dosing knowledge, the timing knowledge, the overdose response knowledge, the “this is what it feels like so use caution” knowledge, all becomes partially obsolete. The supply has changed. Start over.

People who inject drugs have navigated more of these moments in the last decade than in the previous three decades combined. The transition from heroin to fentanyl in the drug supply between roughly 2013 and 2016 erased most of the community knowledge about safe dosing — the tolerance calibrations, the bag-to-bag consistency expectations, the experienced user’s read on a product — in a matter of months. The fentanyl supply is not consistent the way heroin was. Every bag is a different drug.

People who inject drugs have navigated more of these moments in the last decade than in the previous three decades combined.

When xylazine entered the supply around 2019 and became widespread by 2021, the community response took the form of informal education: social media posts about the wounds, word-of-mouth about the naloxone dosing, overdose response trainings updated to include “check for the person still being unconscious after naloxone.” That informal community education system is imperfect. People die while it’s happening. But it is real, and it functions, and it is the primary way that knowledge about a new adulterant reaches the people most at risk.

Medetomidine is happening to the same community while that community is simultaneously losing federal funding for the harm reduction organizations that have historically acted as nodes in the information network. The syringe service programs, the outreach workers, the programs that distributed test strips — the federal funding cuts that began in April 2026 are ending or shrinking many of the programs that would, in previous supply changes, have been the organizations sending workers to neighborhoods with new information.

The community is learning medetomidine in an information environment that is, simultaneously, deteriorating.

The Test Strip Problem Is Also a Medetomidine Problem

There are now test strips for medetomidine, just as there are for fentanyl and xylazine. The federal ban on grant funding for test strips covers medetomidine test strips as well.

This matters in a specific, countable way: medetomidine is often not detectable by fentanyl test strips, and is not reliably detected by xylazine test strips. A person testing their supply who gets a negative fentanyl result and a negative xylazine result can still have medetomidine present and not know it. The information infrastructure — strip distribution, overdose response training, outreach — that would normally adapt to a new adulterant is being defunded at the exact moment the new adulterant needs it most.

What the History of Supply Changes Teaches

The pattern has repeated enough times to constitute a pattern.

In 2013, the drug supply in the Ohio River Valley began shifting from prescription opioids to heroin following a crackdown on pill mill prescribers. The knowledge people had built about OxyContin dosing — how to titrate it, what tolerance looked like, what a bad batch felt like — did not transfer to heroin. The overdose rate in Ohio and West Virginia spiked immediately.

In 2016, fentanyl began appearing in the heroin supply in significant quantities. The same knowledge transition problem repeated. The experienced heroin user’s read on a bag became a liability rather than an asset; experience was now actively dangerous because it suggested false confidence in tolerance calibrations that no longer applied.

In 2019, xylazine. The overdose response rules changed. Naloxone still mattered but it was no longer sufficient and people who had learned overdose response in the pre-xylazine era were operating with incomplete information.

Now medetomidine. The timeline on each supply change has been getting shorter. The adaptation required is the same: new information, distributed rapidly, through whatever networks exist. The federal government’s response to each supply change has been, most recently: to cut the funding for the organizations that do the adaptation work.

What People Who Use Are Doing About It Right Now

In the absence of federal infrastructure, the information moves the way it always does in this world: through text messages, through recovery community organizations, through the remaining syringe service programs, through social media, through word-of-mouth at the program when the outreach worker comes by.

The advice that has been circulating in harm reduction networks as of mid-2026, based on what is known about medetomidine’s pharmacology: never use alone; have naloxone immediately available and plan to give more than usual because the medetomidine component may extend unconsciousness even after opioid reversal; seek medical attention for any overdose involving suspected medetomidine because the withdrawal syndrome is medically serious; if a person falls out and naloxone has been given and they are still not responding, call 911 and tell them it may involve a non-opioid sedative.

This is the community practice guide, assembled without federal support, distributed without federal coordination. It is less complete than it should be. It is what exists.

This is the community practice guide, assembled without federal support, distributed without federal coordination.

The CDC’s provisional 2026 data showed the first sustained overdose death decline in years. Medetomidine’s trajectory — 247 lab reports in 2023 to 8,233 in 2025 — suggests the next phase of the supply change is already underway. The communities navigating it are doing so with less infrastructure than they had for xylazine. Whether the overdose decline holds through the medetomidine transition is the question that no federal data system will answer until the people in those communities have already answered it in the only way available to them.

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The Rize Newsroom tracks emerging drug supply changes. For updates on medetomidine and harm reduction resources: /newsroom/substances/novel-emerging. If you or someone you know has experienced a medetomidine-related overdose or withdrawal, SAMHSA’s National Helpline remains available: 1-800-662-4357.