What is Medetomidine? The latest threat in the street drug supply

By Taylor Knopf

North Carolina’s supply of illicit street drugs is in a constant state of change. People are no longer buying just heroin, fentanyl or opioid pills anymore, as most samples of these illegal drugs have more than one substance in them. People often don’t know what is in their drugs because dealers constantly change the adulterants in the supply. 

This has made it challenging for advocates who want to help people who use drugs stay safe or get into treatment.

“It’s getting really mucky and messy, and things are turning over really quickly,” said Elyse Powell, director of the North Carolina Harm Reduction Coalition. “By the time everyone gets their arms around something, it will be some other thing.”

The UNC Street Drug Analysis Lab, which tests drug samples mailed in anonymously from around the country, has detected 536 unique substances from the more than 23,000 submissions received. 

Over the past three years, the lab started detecting a significant amount of xylazine in the illegal drug supply, something that put the public health community and lawmakers alike on notice. That drug is a veterinary tranquilizer that, when used in humans, frequently causes skin infections at the site of injection that can lead to serious long-term complications, even death. 

But earlier this year, a different veterinary tranquilizer called medetomidine — sometimes referred to as “Rhino Tranq” — overtook xylazine in its prevalence in the supply, according to the UNC lab data. (There’s also a version of medetomidine called Dexmedetomidine, also known by the brand name Precedex, which is a sedative used in hospitals to keep surgery patients and infants on ventilators comfortable.)

Public health officials are spreading the word about this new substance in the illegal drug supply. They’ve been providing education on which symptoms to look out for and how to treat someone going through withdrawal from substances laced with the animal tranquilizer. 

Meanwhile, substance use experts argue that the crackdown on xylazine may have helped drive the increase in medetomidine use. They warn that placing drugs in the controlled substances schedule can push illegal manufacturers to find other substitutes, creating new risks.

What to know about medetomidine

Unlike its cousin xylazine, medetomidine doesn’t appear to cause skin wounds. However, it is significantly more potent than xylazine and can cause long periods of sedation accompanied by a slower heart rate, along with low blood pressure, dizziness, fatigue, shortness of breath, nausea, blurred vision and confusion. 

UNC street drug lab researchers found that medetomidine in the street supply has also been associated with hallucinations, which is not a typical side effect of opioids or Dexmedetomidine, the version of medetomidine used in hospitals. 

Medetomidine is commonly mixed with fentanyl, an opioid that is more potent than heroin and comes with a higher risk of overdose. If someone appears to be overdosing on fentanyl mixed with a sedative such as medetomidine, a responder should administer naloxone, a drug usually given to reverse the opioid’s effects and restore normal breathing. 

However, naloxone does not reverse the effects of medetomidine. So that same person may remain unconscious or heavily sedated even after their breathing improves, according to guidance from Philadelphia Department of Public Health Division of Substance Use Prevention and Harm Reduction, which has led the country in the response to medetomidine laced drugs. 

In that instance, the goal of naloxone administration is to restore breathing to avoid an overdose death — not necessarily to wake the person.

But one of the most insidious aspects of medetomidine use is that it can be most dangerous when someone stops using it. 

Dangers of medetomidine withdrawal

Medetomidine withdrawal symptoms can start within just hours of last use and can trigger cardiac problems severe enough to require hospitalization. 

This spring, Nabarun Dasgupta, director of the UNC Street Drug Lab, testified before Congress about the dangers of the ever-changing illegal drug supply and called medetomidine withdrawal a nightmare that can lead to a weekslong stay in an intensive care unit. 

“Medetomidine withdrawal is unlike anything most emergency physicians have seen before,” Dasgupta said in his written testimony. “When people use fentanyl that’s been laced with medetomidine, abrupt stopping can trigger a crisis that hits fast and hard.”

He explained that withdrawal symptoms often start with nausea and vomiting that doesn’t respond to common anti-nausea medications. The situation can escalate to a racing heart, high blood pressure, sweats, tremors and delirium. 

“What makes it so alarming is that the standard tools doctors rely on — benzodiazepines, opioids, even common anti-nausea drugs — do remarkably little to slow it down,” Dasgupta wrote. “Doctors who have treated it describe a visceral sense of encountering something fundamentally different from anything in their experience.” 

One of the earliest outbreaks of medetomidine happened in Philadelphia and Pittsburgh. Dasgupta wrote that the majority of patients diagnosed with severe medetomidine withdrawal in those Pennsylvania hospitals ended up in the ICU, with many requiring IV sedation for days. Pennsylvania jails were hit with this problem as well and found themselves ill-equipped to help people who were arrested and thereby forced into immediate withdrawal. 

The Centers for Disease Control and Prevention’s medetomidine summary page includes recommendations for clinicians treating medetomidine withdrawal, as well as information for public health workers and laboratories that may encounter it. To avoid damage to the heart or brain, the CDC warns those who believe they may have used a drug contaminated with medetomidine to call 911 or go to the hospital if they can’t stop throwing up, have chest pain, are going in and out of consciousness or are experiencing severe withdrawal symptoms.

Unintended consequences of drug scheduling 

Substance use experts point to Pennsylvania as an example of what could happen if lawmakers take the same path with medetomidine that they did with xylazine. 

In his written testimony, Dasgupta noted that xylazine was added as a Schedule III substance in Pennsylvania in May 2024. Immediately following, medetomidine began replacing xylazine in the illicit drug supply. In Pittsburgh, medetomidine is now more prevalent than fentanyl, he said.

A recent study published in the International Journal of Drug Policy found that the addition of xylazine to the scheduled drug list did not lead to a significant decrease of xylazine reports in the drug supply; however, there were more medetomidine reports following the scheduling of xylazine. 

Part of what makes the situation with medetomidine more complicated, according to Dasgupta, is its human medicine counterpart, Precedex, which plays a legitimate role in hospitals. 

“Precedex is used widely in hospitals for sedation (e.g., babies on respirators) because it is not a controlled substance. It is also an adjunct treatment for bipolar disorder and schizophrenia,” Dasgupta wrote. “If xylazine is a precedent, then scheduling medetomidine too restrictively will be massively disruptive to human medicine.”

Powell sees the same pattern playing out every time something new enters the supply. 

“There’s just this sort of knee jerk response to criminalize it,” she said. “The best evidence that we have is the reason there is medetomidine in the supply is because xylazine was scheduled … Every time they schedule one of these new things, it’s just replaced with something else, and more often than not, that something else is worse.”

“So we’re just sort of playing this legal whack-a-mole,” she said.

Is medetomidine in NC?

Powell’s organization, the North Carolina Harm Reduction Coalition, is already seeing medetomidine turn up locally through the testing of drug samples analyzed in the Triangle area. The UNC lab has picked it up in North Carolina samples as well. Medetomidine first showed up in the UNC Street Drug Lab’s data back in 2022, but its prevalence started climbing in the summer of 2024.

The North Carolina Department of Health and Human Services sent a provider alert on June 8 flagging emerging substances, including medetomidine, in the state’s street drug supply. 

“The emergence of substances including medetomidine and cychlorphine reflects the continued evolution of the drug supply,” the alert reads. “Similar to xylazine, many individuals exposed to these substances may be unaware they are present in the drugs they are using. Increased awareness among clinicians, emergency medical services, hospitals, and treatment providers will be important to overdose response, identifying and treating withdrawal symptoms, and reducing morbidity and mortality associated with exposure to emerging adulterants.” 

Substance use experts say staying on top of a constantly shifting drug supply depends heavily on testing. Powell said developing new rapid response test strips is a slow process as manufacturers work through issues like false positives before they are reliable enough to hand out to people.

Medetomidine test strips are available, but they are expensive, she said. Medetomidine test strips run about $200 for a box of 100, compared to about $35 for a box of 100 fentanyl test strips. For Powell’s organization, which sees more than 5,000 people a year, that cost difference adds up.

Funding for testing of illegal drugs has also grown more uncertain. The federal Substance Abuse and Mental Health Services Administration issued a “Dear Colleague” letter earlier this year banning the use of SAMHSA grant funds for testing strips, which Powell said is a significant loss. 

The letter is part of the Trump administration’s step back from harm reduction, a research-backed public health approach that aims to minimize the ill effects of drug use and keep people alive and connected to support services, even as they’re not yet engaged in treatment. The administration has discouraged certain harm reduction interventions, like test strips, arguing they only enable illegal drug use, even as those methods have strong data backing their effectiveness. 

Some worry that the tone set by the federal agency could impact other harm reduction funding sources down the road.

“So I’ll say NCHRC has been lucky in that we’ve had other available funding where we’ve been able to purchase it for now,” Powell said. “But I also hear the nervousness with our funders.”

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