Emergency rooms across Philadelphia have reported a rise in patients experiencing withdrawal from medetomidine, a veterinary sedative increasingly mixed with fentanyl.
The citywide crisis — which first drew attention in May 2024 — is fueled by medetmodine’s rapid and life-threatening onset of withdrawal symptoms. In interviews with The Daily Pennsylvanian, physicians and researchers at Penn Medicine highlighted their ongoing efforts to treat cases, both at the hospital and following a patient’s discharge.
“There is overlap in withdrawal from medetomidine and withdrawal from opioids,” Ashish Thakrar, an assistant professor at the Perelman School of Medicine, said in an interview with the DP. He added that withdrawal from both types of drugs has been linked to elevations in blood pressure and heart rate, along with nausea, vomiting, and tremors.
The increase in medetomidine within the city’s fentanyl supply comes amid the declining use of xylazine, a veterinary tranquilizer typically mixed with fentanyl that was made illegal for human use in Pennsylvania in May 2024.
According to research by the Philadelphia Department of Public Health, the percentage of street opioid samples with medetomidine grew from 29% to 87% by November 2024, while xylazine’s percentage in samples across the city decreased from 97% to 42% during the same period.
Thakrar emphasized the difficulty of predicting severe cases of withdrawal, adding that the increase in medetomidine has led to an overall rise in hospital visits. According to The New York Times, Philadelphia public health records indicate an increase of nearly 4,500 hospital emergency department admissions between 2023 and 2025.
Emily Casey — a clinical pharmacy specialist in pain management and substance use disorders at Penn Medicine — told the DP that the Philadelphia health system “responded really well” to the crisis by making changes “very quickly in terms of the level of care that patients were needing.”
She added that the health system also responded by “changing the protocols and policies” associated with the drug’s withdrawal.
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“It’s really hard,” Casey said. “We’re on the front lines. Us, Jefferson, and Temple are some of the only places in the United States seeing this.”
Despite the difficulty, some professionals pointed to the success of initial treatment measures.
In an interview with the DP, Associate Professor of Family Medicine and Community Health at Penn Medicine Judy Chertok compared the rise of medetomidine to the beginning of the COVID-19 pandemic, in which the healthcare system rushed to assess symptoms and develop guidelines.
She said it has “been incredible to watch” pharmacists across the city collaborate on how to address the issue.
According to Thakrar, many approaches rely on tracking illicit drugs throughout the city. Multiple organizations — including PA Groundhogs and the Philadelphia Department of Public Health — release quarterly drug-checking reports.
“I think it’s vitally important for us to keep track of what is in the unregulated drug supply,” Thakrar said. “I think if we fund and invest in that, then we’ll be able to keep track early of what these changes are.”
The crisis also led to concerns about how to safely discharge patients, as many are homeless or cognitively impaired.
In an interview with the DP, Emily Avellino — the program manager for the Center for Opioid Recovery and Engagement at Penn Medicine — spoke to the need for more providers, better housing options, and improved overall stability for people with addiction, particularly in neighborhoods like Kensington.
“That is our whole goal, to let them know that they’re still human,” Avellino said. “It’s up to us to provide that — even if it’s clothing, a snack, whatever that looks like — to get them to stay, go into treatment, and try to recreate a new life.”
