Medetomidine, a veterinary sedative, mixed into fentanyl has sent thousands to hospitals, not only for overdose but for life-threatening withdrawal. It is spreading to other cities.
By Jan Hoffman
Photographs by Hannah Yoon
Dec. 15, 2025Updated 6:59 a.m. ET
Around 2 a.m., Joseph felt the withdrawal coming on, sudden and hard. He fell to the floor convulsing, vomiting ferociously. The delirium and hallucinations were starting.
He shook awake his friend, who had let him in earlier to shower, wash his clothes and grab some sleep. “Do you have a few dollars?” he pleaded. “I have to get right.”
The friend, a community outreach worker who had been trying for years to get him into treatment, looked up at him standing over her raving and unfocused.
“Either leave or let me call an ambulance,” she demanded.
At 34, Joseph (who, with his friend, recounted the evening in interviews with The New York Times) had been through opioid withdrawals many times — on Philadelphia streets, in jail, in rehab. But he had never experienced anything as terrifyingly all-consuming as this.
A new drug has been saturating the fentanyl supply in Philadelphia and moving to other cities throughout the East and Midwestern United States: medetomidine, a powerful veterinary sedative that causes almost instantaneous blackouts and, if not used every few hours, brings on life-threatening withdrawal symptoms.
It has created a new type of drug crisis — one that is occasioned not by overdosing on the drug, but by withdrawing from it.
Since the middle of last year, Philadelphia’s hospitals have been strained by patients coming in with what doctors have identified as medetomidine withdrawal. Although the heart rate slows drastically right after use, in withdrawal the opposite occurs: The heart rate and blood pressure become catastrophically high. Patients experience tremors and unstoppable vomiting. Many require intensive care.
Joseph didn’t have time to go to a hospital. His heart was pounding so frantically that he felt trapped in a never-ending panic attack. Slick with sweat and retching, nerves firing in pain, he clutched the bills his friend had angrily thrust at him and left her house in South Philly. He lurched down the dark street, hoping to buy just enough dope to feel less sick.
A city under a new siege
Philadelphia has long been a sentinel in the country’s ever-changing drug crisis. It was only a few years ago that xylazine, a large-animal tranquilizer that can cause rot and abscess in human tissue, appeared in the fentanyl throughout the drug-battered Kensington neighborhood. Soon, it began churning across the country.
Now xylazine is fading from Philadelphia, replaced by medetomidine, a 30-year-old veterinary sedative and anesthetic that is up to 200 times as potent. It has been detected in 91 percent of the city’s tested supplies of fentanyl, according to the Center for Forensic Science Research and Education, a national drug-checking lab.
In withdrawal, some patients become mute, appearing unaware as they defecate on the floor or vomit on nurses. The very high blood pressure can cause brain damage.
“Our I.C.U.s have been overwhelmed,” said Dr. Daniel del Portal, an emergency room physician and hospital administrator at Temple Health, adding that doctors, emergency medical workers and outreach teams now refer to “the withdrawal crisis.”
According to Philadelphia public health records, in the first nine months of 2025, there were 7,252 admissions to hospital emergency departments for withdrawal, compared with 2,787 for all of 2023.
Medetomidine has also been reported in Massachusetts, Maryland, North Carolina, Florida, Missouri, Colorado, Ohio and, increasingly, in New Jersey and Delaware. Chicago had a cluster. Pittsburgh is beginning to be inundated.
From a drug dealer’s grimly economic perspective, medetomidine is a smart choice. It is mostly manufactured in China and can be purchased cheaply online from suppliers of veterinary medicine and research chemicals. It is so addictive that dealers don’t need to mix much into fentanyl.
Right after snorting, injecting or smoking fentanyl with medetomidine, users collapse. At 8:30 a.m. on a busy weekday, people were splayed along Kensington Avenue, oblivious to trains roaring overhead and ambulances shrieking by. A man lay on his side, his weight crushing an arm and leg. Another sprawled on his back, his head pillowed by the curb. When the drug wears off, people come to, wakened by fresh craving.
Kelli Murray, a peer support specialist with the University of Pennsylvania addiction medicine program, lugged a wagon filled with sweatpants, underwear, deodorant, water bottles, Doritos and wound care kits.
A brittle-thin young woman named Jessica wobbled over to the wagon and pulled out a hoodie. She felt imprisoned by the drug, she said. “I feel so stuck. I don’t know how to get off it. It’s making me crazy.”
Ms. Murray, who is herself in recovery, asked: “You want to come into the hospital?”
Jessica shook her head. “I’m too scared.”
People have such a dread of withdrawal that many refuse to go to treatment centers, which, they fear, will manage their symptoms inadequately. Some speak of making it to a hospital, only to spend hours in escalating distress, watching as patients with other emergencies — car accidents, stabbings — are taken first. In agony, they leave, to medicate themselves on the street.
One last taste
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