Pittsburgh-area doctors are sounding the alarm on medetomidine, a veterinary tranquilizer that’s increasingly permeating street drugs like “flysky” in Western Pennsylvania.
And it’s not abating anytime soon. The drug continues to become more prevalent, and doctors say there are minimal clear treatment options for the severe withdrawal process.
Unlike heroin or fentanyl, medetomidine doesn’t respond to naloxone products such as the nasal spray Narcan to reverse opioid overdose, said Dr. Michael Lynch, senior medical director of UPMC Health Plan’s Quality and Substance Use Disorder Services.
“The people don’t wake up, which can be alarming when you’re giving naloxone,” said Lynch, who is also an associate professor of emergency medicine and toxicology at the University of Pittsburgh School of Medicine. “People continue to sleep.”
Fentanyl, heroin and other illicit street drugs are being found laced with varying amounts of medetomidine, creating a substance known as “flysky” on the street.
Medetomidine is being used as a cutting agent, or adulterant. It dilutes the pure drug while providing the same type of effect and yielding more profit for drug dealers, said Justin Todd, co-founder of AddictionResource.net, which provides free addiction treatment resources nationwide.
“A lot of times, people aren’t necessarily seeking this out. Their intention is to buy heroin or fentanyl, and this is a cutting agent that they might not be aware that they’re buying,” said Todd, whose organization is based in Michigan.
It’s difficult to determine whether medetomidine is actually causing overdose deaths, Lynch said, as the opioid often is the main contributor.
“It’s certainly found in people who die from overdose,” he said. “What’s harder to know is how much medetomidine is causing overdose deaths.”
Adding cutting agents has been a common practice with all illicit drugs, Todd said. Another veterinary medicine, xylazine, started being used before medetomidine.
Medetomidine is 100 to 200 times more potent than xylazine and can cause longer-lasting sedation, low heart rates and more severe withdrawal symptoms, according to the Allegheny County Health Department.
In some cases, medetomidine is used to sedate horses, which are hundreds of pounds heavier than humans.
When people buy illicit drugs, the doctors said, there’s no way of knowing what’s actually inside them, including cutting agents.
Pervading local hospitals
Medetomidine was first documented in illicit drug supply in Maryland in 2022. Since then, it has been identified in states including New Jersey, Ohio, California, Colorado, Illinois and Missouri.
However, “most have not had the same degree of experience as we have,” Lynch said. The drug is coming into Western Pennsylvania from supply in both the east and west, which can lead to some variations in mixtures, he added.
Medetomidine wasn’t identified at all in Pennsylvania when drug supply was tested in the first quarter of 2024, Lynch said. But, by the second quarter of 2025, it was present in 83% of samples tested in Pennsylvania, he said, according to the most recent PA Groundhogs Adulterant Report.
“It went from none to a lot very quickly,” Lynch said. “Starting around October or so, we started seeing patients presenting with withdrawal. At the time, we weren’t sure what it was that was causing such severe withdrawal — it was very unusual.”
At UPMC, hospitals used to see a few cases a month or week, but since an acceleration from March through May, hospitals have been seing a few cases a day, he said, totaling several hundred since the beginning of 2025.
“It seemed to really take off,” Lynch said. “It’s continued to gradually grow from there.”
UPMC Mercy is admitting about two or three patients per day for withdrawal from medetomidine, part of a three- or four-patient admitting total across all of UPMC’s Pittsburgh hospitals, according to Lynch.
At any one time, an intensive care unit’s patients at one hospital could include a third going through withdrawal from medetomidine, he said.
“If it’s not treated, people can die from it,” Lynch said.
Dr. Brent Rau, medical director for emergency medicine at Allegheny General Hospital, said there’s been a surge of what is believed to be mostly medetomidine and related illnesses. He believes about one patient or so per day or a few per week can be assumed to be undergoing medetomidine withdrawal.
And those patients are “pretty notable,” he said, as they are time-intensive.
“Any time you have a recreational drug that … doesn’t respond to reversal agents, it’s very concerning,” Rau said.
However, it’s hard to know exact data and numbers because it doesn’t show on a urine drug screen, according to Rau. Tests can take many days to come back, which isn’t helpful for the patient in the short term.
“We generally make (the) assumption that that’s what that is, and I think that’s a correct assumption,” he said. “This is a relatively new thing for us.”
In the emergency department, Rau said, it doesn’t matter what drug is the cause — only that the patient is treated. The most important thing with medetomidine withdrawal is making sure they can breathe, either through supplemental oxygen or a tube.
“I would say it’s definitely ramped up over the summer months compared to last winter,” he said. “It’s been a steady summer of this — it hasn’t shown evidence of slowing down.”
Dr. William Jenkins is director of the emergency department at Independence Health System’s Frick Hospital and EMS medical director for the health system and for Mutual Aid EMS. He concurred that medetomidine is part of the “growing trend” of adulterating either heroin or fentanyl with substances that aren’t narcotic.
Jenkins said Independence Health System is seeing the effects of medetomidine. There’s no way yet to quantify it because the cases are “hard to immediately identify,” he said.
“It’s a very dangerous, almost roulette, game that is played with patients with opioid-use disorders,” Jenkins said.
Life-threatening withdrawal
In the brain, medetomidine turns down the adrenaline system, making heart and blood pressure low, Lynch said, which is why it can make people sleepy and have respiratory effects.
“When people use medetomidine regularly, and their body gets used to having their adrenaline system turned down … missing that means their adrenaline system essentially turns way up,” he said, causing nausea, vomiting, high blood pressure, confusion or delirium, high heart rate, tremors or shaking, flushing and sweating, plus other symptoms.
That’s why people end up being admitted to the ICU, which is not usual for typical opioid withdrawal, Lynch said.
“It leads to a new and different kind of toxicity,” he said of the drug.
The nausea and vomiting can be so bad that people can’t even get pills down that may help them, he said.
Treatment protocols are still being developed statewide and nationwide, but Lynch said UPMC has been using dexmedetomidine, a non-opioid drug typically used to manage pain and sedation in humans, according to the National Institutes of Health. It’s only allowed to be used in the ICU, Lynch said.
Jenkins said when patients are given Narcan, sometimes they wake up a little agitated in various states of withdrawal, which can be dangerous not only to the patient but to the staff. These challenges are faced weekly in Independence’s emergency departments, he said.
“We’re giving these people Narcan, we’re expecting them to wake up — and they’re not,” he said of medetomidine patients. “It’s hard to stay ahead of it. Tomorrow’s drug creates a new learning challenge and new problem.”
Combating medetomidine
Jenkins said what’s needed is a more rapid way to identify medetomidine and other adulterants sooner in the process.
He said Prevention Point Pittsburgh offers rapid-test strips that can be used to test a drug for medetomidine. Lynch just purchased some and is hoping to distribute them to UPMC’s emergency departments.
“There’s some pause to make sure that they work as well as we want them to,” he said. “It’s something to try, but it’s not a perfect solution.”
And without a substantial understanding of chemistry and the right equipment, as well as significant laboratory testing, there’s no way of knowing what’s inside street drugs, Rau said.
“If there’s illegal narcotics … the adulterations are there,” Jenkins said. “It’s around us — I’m sure of it.”
Megan Swift is a TribLive reporter covering trending news in Western Pennsylvania. A Murrysville native, she joined the Trib full time in 2023 after serving as editor-in-chief of The Daily Collegian at Penn State. She previously worked as a Jim Borden Scholarship intern at the Trib for three summers. She can be reached at mswift@triblive.com.