Medetomidine, a veterinary tranquilizer, has overtaken xylazine as the more common sedative adulterant in tested illicit drug samples, according to data from the UNC Street Drug Analysis Lab. The crossover occurred earlier this year in the lab's national sample data, and the compound is also turning up in North Carolina samples.
The detail that matters most for families and emergency clinicians is not the overdose picture, which has been described before. It is what happens when someone stops. Medetomidine withdrawal can begin within hours of last use and can escalate to cardiac problems severe enough to require hospitalization, and the medications hospitals normally reach for do very little to blunt it.
That reframes where the danger sits. A person can survive an overdose, reach a hospital or a jail cell, and then enter a crisis that the building is not equipped to manage.
The Crossover Point in the Lab's Sample Data
The UNC lab tests samples mailed in anonymously from around the country and has detected 536 unique substances across more than 23,000 submissions. Medetomidine first appeared in the data in 2022, and its prevalence began to climb in the summer of 2024.
Unlike xylazine, medetomidine does not appear to cause the severe skin wounds that made its predecessor visible and politically salient. It is considerably more potent, and it produces prolonged sedation along with a slowed heart rate, low blood pressure, dizziness, fatigue, shortness of breath, nausea, blurred vision, and confusion. Lab researchers have also linked it to hallucinations, which are not typical of opioids.
The state has moved on to clinician awareness. The North Carolina Department of Health and Human Services issued a provider alert flagging emerging substances, including medetomidine, stating that their emergence "reflects the continued evolution of the drug supply" and that many people exposed are unaware the substances are present, as North Carolina Health News reported.
Naloxone should still be given for any suspected opioid overdose, because fentanyl is nearly always involved. It restores breathing. It does not wake someone from medetomidine sedation, and Philadelphia's guidance for responders advises judging the response by breathing rather than by alertness.
Withdrawal Arrives in Hours and Resists Standard Treatment
Nabarun Dasgupta, who directs the UNC lab, testified before a congressional subcommittee this spring that the syndrome is outside the scope of ordinary clinical experience. Medetomidine withdrawal, he wrote in his submitted testimony, is "unlike anything most emergency physicians have seen before."
The pattern he described begins with nausea and vomiting that do not respond to common anti-nausea medications, then escalates to a racing heart, high blood pressure, sweating, tremors, and delirium. He wrote that benzodiazepines, opioids, and standard anti-nausea drugs do remarkably little to slow it. In Pennsylvania hospitals that saw early clusters, most patients diagnosed with severe medetomidine withdrawal ended up in intensive care, many requiring intravenous sedation for days. Jails in the same state were caught without the capacity to manage people forced into abrupt withdrawal upon arrest.
The CDC's health advisory tells anyone who believes they used a contaminated drug to call 911 or go to a hospital if they cannot stop vomiting, have chest pain, are going in and out of consciousness, or have severe withdrawal symptoms. The agency frames this as preventing damage to the heart or brain, and that is the correct threshold for a family member deciding whether to wait.
A Scheduling Decision That May Have Driven the Substitution
The substitution pattern is the accountability question underneath the clinical one. Xylazine was added to Pennsylvania's controlled substances schedule in 2024, and medetomidine began replacing it in the supply immediately afterward. In Pittsburgh, Dasgupta told Congress that medetomidine is now more prevalent than fentanyl itself.
A study in the International Journal of Drug Policy found that scheduling xylazine did not produce a significant decline in xylazine reports, while medetomidine reports increased afterward. Elyse Powell, who directs the North Carolina Harm Reduction Coalition, described the cycle to North Carolina Health News as "playing this legal whack-a-mole,"adding that replacements have generally been worse than what they replaced.
There is a complication specific to this compound. Dexmedetomidine, marketed as Precedex, is a legitimate hospital sedative used for ventilated patients, including infants, and Dasgupta noted it also serves as an adjunct treatment in bipolar disorder and schizophrenia. He warned in his testimony that if xylazine is the precedent, scheduling medetomidine too restrictively would be massively disruptive to human medicine.
None of that argues against acting. It argues for acting with a plan for what replaces the compound, since the supply has now turned over twice in three years and each replacement has been harder to manage clinically than the one before it.
Testing Costs and Funding Rules Shape Who Finds Out
Detection is the limiting factor, and it is a budget problem. Medetomidine test strips run about $200 for a box of 100, against about $35 for a box of 100 fentanyl strips. For the North Carolina Harm Reduction Coalition, which serves more than 5,000 people a year, that difference determines how many samples are ever checked. The Substance Abuse and Mental Health Services Administration issued a letter this year barring the use of its grant funds for test strips, which removed one funding path for programs that distribute them, and Powell has said other funders have grown more cautious in response.
The people most exposed are those using illicit opioids without knowing what is in them, along with anyone entering abrupt withdrawal in a jail, a hospital, or a treatment program without staff who recognize the syndrome. Families supporting someone who uses drugs should know that naloxone remains essential and should be on hand, that a partial response is not reassurance, and that withdrawal is a medical situation rather than something to wait out at home.
Anyone seeking treatment or support can call the SAMHSA National Helpline at 1-800-662-4357, which is free, confidential, and available 24/7. It provides referrals to local treatment programs and support organizations.
Key Questions Answered
What is medetomidine? A potent veterinary sedative in the same drug class as xylazine and clonidine. It is not approved for human use and is appearing as an adulterant in illicit fentanyl.
Does naloxone work? It reverses the opioid component and restores breathing, which is what prevents death. It does not reverse medetomidine sedation, so responders should judge the response by breathing rather than alertness.
Why is withdrawal the bigger concern? It can begin within hours of last use, escalate quickly to a racing heart, high blood pressure, tremors, and delirium, and resist benzodiazepines, opioids, and standard anti-nausea drugs.
When should someone go to a hospital? The CDC advises calling 911 or going to a hospital for uncontrollable vomiting, chest pain, going in and out of consciousness, or severe withdrawal symptoms.
Is it in North Carolina? Yes. The UNC lab has detected it in North Carolina samples, a harm reduction group is finding it in the Triangle area, and the state health department has alerted providers.
Can it be tested for? Test strips exist but cost roughly $200 per box of 100 against about $35 for the same quantity of fentanyl strips, and one federal funding path for strips was closed this year.
Where can someone get help? The SAMHSA National Helpline, 1-800-662-4357, is free, confidential, and available 24/7.
