The share of patients with opioid use disorder who needed dexmedetomidine, an intensive care sedative, to control withdrawal rose from about 6% to about 20% at two Philadelphia hospitals after dexmedetomidine entered the local fentanyl supply, according to a Penn Medicine study in JAMA Internal Medicine. In the final three months studied, ending in September 2025, the figure reached about 32%.
The findings put hospital-level numbers on what Philadelphia doctors have described for more than a year. Withdrawal from fentanyl mixed with medetomidine can drive heart rate and blood pressure to dangerous levels, and a growing share of patients need ICU-level care just to get through it.
For families of people who use drugs, and for hospitals in other cities, the data matter because this withdrawal cannot be handled like ordinary opioid withdrawal. Stopping suddenly, whether during an arrest, a hospital stay, or a gap in supply, can quickly become a medical emergency.
Hospital Records Show a Sharp Climb
Researchers reviewed records from two Philadelphia hospitals from 2020 through September 2025. They used dexmedetomidine treatment as a marker of severe withdrawal, because the drug is chemically related to medetomidine and is used to treat the syndrome.
Before medetomidine appeared in the local drug supply, around mid-2024, just under 6% of patients with opioid use disorder received dexmedetomidine, according to a Penn Medicine announcement. That rose to roughly 20% afterward. Patients who received dexmedetomidine were also more likely to receive methadone than patients who did not, 79% compared with 50%, and more likely to receive buprenorphine, 36% compared with 26%.
"It was striking that, in the last quarter of our study, a third of patients required intensive care unit management for withdrawal from fentanyl mixed with medetomidine," said Dr. Ashish Thakrar, an assistant professor of general internal medicine at Penn. "Clinically, we recognize that we are in a new era of withdrawal management."
A Withdrawal Syndrome That Strains the Heart
Medetomidine is a veterinary sedative that Penn researchers describe as 100 to 200 times more powerful than xylazine, an earlier additive in the illicit opioid supply. Withdrawal can bring a racing heart, extreme anxiety, nausea, and vomiting. Treatment with dexmedetomidine infusions usually happens in intensive care, because the drug can push heart rate and blood pressure dangerously low.
A CDC report from Philadelphia described 165 patients at three health systems with suspected medetomidine withdrawal between September 2024 and January 2025. Of those, 91% needed ICU care, and 24% required a breathing tube. Medetomidine appeared in 72% of illegal opioid samples tested in the city in late 2024, while xylazine detection fell from 98% to 31%.
"Historically, heroin withdrawal without these adulterants could be managed in outpatient or minimally monitored inpatient settings," Thakrar said. Dr. Margaret Lowenstein, research director for the Penn Center for Addiction Medicine and Policy, added, "Patients are coming to us very sick, and we have had to rapidly adapt our treatments to serve the patients in front of us."
MedicalDaily previously reported that medetomidine had overtaken xylazine in the illicit drug supply, with withdrawal emerging as the bigger danger. A later report shared patients' own accounts of extreme sedation and withdrawal. The Penn study adds a measure of how fast demand for ICU-level withdrawal treatment grew at the hospital level.
Limits of a Two-Hospital Study
The data come from two hospitals in one city. Philadelphia's drug supply changed earlier and more completely than in many places, so the numbers may not reflect what hospitals elsewhere are seeing.
The study used dexmedetomidine treatment as a stand-in for severe cases. That is an indirect measure, and changes in how doctors chose to treat withdrawal over time could also affect the numbers. The data end in September 2025, so current rates may differ. The research was funded by the National Institute on Drug Abuse.
"You can't address something you can't see," said Dr. Tyler Boyce, a fellow in pulmonary and critical care medicine at Penn, who said the tracking approach could help hospitals and public health officials plan their responses.
Guidance for Families and Hospitals Beyond Philadelphia
People who use illicit fentanyl in areas where medetomidine is spreading face the greatest risk, along with anyone forced to stop suddenly, such as during an arrest or hospital admission. Hospitals with limited ICU beds may feel the strain most if cases rise.
Each patient who needs an ICU bed for withdrawal takes a bed that could otherwise go to someone with a heart attack, stroke, or serious infection. Smaller community hospitals may need to transfer patients, which can mean longer trips and higher bills for families. Jails and detox programs that are not set up for intensive monitoring may also struggle when people arrive in withdrawal.
Naloxone should still be given in any suspected overdose because it reverses fentanyl, even though it does not reverse medetomidine sedation. A person who is breathing but still very sleepy after naloxone needs emergency care. A racing heart, severe vomiting, confusion, or extreme agitation after stopping fentanyl also calls for prompt medical evaluation.
People seeking treatment can call SAMHSA's National Helpline at 1-800-662-4357, which is free and confidential. Telling clinicians about recent fentanyl use can help them anticipate severe withdrawal. Health departments in other cities may use similar hospital data to spot medetomidine's arrival earlier.
Key Questions Answered
What did the Penn study find? At two Philadelphia hospitals, the share of patients with opioid use disorder needing dexmedetomidine for withdrawal rose from about 6% to about 20% after medetomidine arrived in mid-2024, reaching about 32% in the final quarter studied.
What is medetomidine? It is a veterinary sedative, described by Penn researchers as 100 to 200 times more powerful than xylazine, that has been mixed into illicit fentanyl.
Why is the withdrawal so dangerous? It can cause a racing heart, extreme anxiety, and vomiting, and treatment often requires ICU care because the medicine used can drop heart rate and blood pressure.
Does naloxone still work? Naloxone reverses fentanyl and should still be used in any suspected overdose, but it does not reverse medetomidine sedation.
Do the results apply outside Philadelphia? Not necessarily. The study covered only two hospitals, and drug supplies vary by region.
Published by Medicaldaily.com
