The Drug Replacing Xylazine in the Supply Doesn't Answer to Naloxone

Here’s what a fentanyl test strip can no longer tell you: whether the withdrawal that hits in a few hours is going to require an ambulance.

Medetomidine — a veterinary sedative 100 to 200 times more potent than xylazine — has taken over Philadelphia’s illicit opioid supply with a speed that outran the harm reduction system built to track it. Samples testing positive for it rose from 29% in May 2024 to 90% by March 2026, while xylazine — the adulterant it’s replacing — fell from 97% to 28% over the same window. It’s since turned up in North Carolina, Ohio, and Illinois.

Naloxone reverses opioids. It does nothing for medetomidine, and right now most of the country’s harm reduction infrastructure is built around the assumption that it does.

Nabarun Dasgupta, who directs the UNC Street Drug Lab and testified before Congress about the shift this spring, described what emergency physicians are now seeing: “Medetomidine withdrawal is unlike anything most emergency physicians have seen before… abrupt stopping can trigger a crisis that hits fast and hard.” The numbers back him up — tachycardia over 100 beats per minute, blood pressure spikes above 180/100, uncontrollable vomiting, tremors — severe enough that most people hospitalized for it need an ICU bed, not a hallway cot.

Test strips for medetomidine exist. They cost roughly $200 for a box of 100, against $35 for the equivalent box of fentanyl strips — a price gap that matters more than it should, because federal funding for buying any drug-checking supplies just ended in April 2026.

Elyse Powell, who directs the North Carolina Harm Reduction Coalition, isn’t optimistic that scheduling medetomidine as a controlled substance — the government’s default response to xylazine — will do much this time either: “There’s just this sort of knee jerk response to criminalize it,” she said. “Every time they schedule one of these new things, it’s just replaced with something else.” Pennsylvania scheduled xylazine in May 2024. Medetomidine’s rise started almost immediately after.

If you use, the practical version of this is blunt: a fentanyl strip alone can no longer tell you what’s in your supply. If a medetomidine strip isn’t in reach, plan for the fact that this batch may sedate you longer and harder than you’re used to, and that whoever’s with you needs to know naloxone might not be enough this time. That’s not a reason to panic. It’s the same reason you’d check twice before crossing a road you thought you knew — the ground shifted, and the people paying attention to it are telling you exactly how.