Slow Heart Rate: A Deadly Sign of Xylazine-Fentanyl Overdose
Press Release: Unveiling a Lifesaving Discovery
A groundbreaking study from Mount Sinai researchers has uncovered a critical link between an abnormally slow heart rate and xylazine-fentanyl overdose, a combination that has become a growing concern in the Northeastern United States. This discovery could be a game-changer for emergency medicine, enabling doctors to identify and treat this novel drug overdose more effectively.
New York, NY, January 13, 2026 -- A team of dedicated researchers has made a significant breakthrough in understanding the symptoms of xylazine-opioid overdose. Led by Dr. Jennifer Love, Assistant Professor of Emergency Medicine, the study reveals that bradycardia, a condition characterized by an unusually slow heart rate, is a key indicator of exposure to xylazine, a powerful animal sedative often mixed with illicit fentanyl.
But here's where it gets controversial: xylazine is not intended for human use, yet it's increasingly found in the fentanyl supply, particularly in the Northeast. This study, published in Addiction, highlights the urgent need for better detection methods and raises questions about the unknown health effects of this drug combination.
"Opioid users are unknowingly exposed to xylazine, and we're still in the dark about its full impact on patients," says Dr. Love. "Doctors in emergency rooms can't test for xylazine at the bedside, so they often miss this crucial piece of information. By associating bradycardia with xylazine overdose, we can empower ER doctors to provide better harm reduction counseling and resources to patients."
Xylazine, a veterinary drug, has been found in 25% of the U.S. fentanyl supply. Its overdose can lead to severe skin lesions, sedation, hypothermia, and heart problems. However, due to its unauthorized use in humans, there's a knowledge gap about its effects on patients.
The Mount Sinai team, in collaboration with the American College of Medical Toxicology's Toxicology Investigators Consortium, conducted a comprehensive study of 1,289 adult patients suspected of opioid overdose across 10 healthcare institutions in the U.S. from 2020 to 2023. They discovered that 238 patients had xylazine in their blood, and 6% of these patients exhibited bradycardia upon arrival at the ER, compared to only 2% of patients without xylazine.
"Bradycardia is a significant indicator of xylazine-fentanyl overdose in this specific patient group," explains Dr. Love. "It's a clinical sign that can help doctors identify and treat these cases more effectively."
Interestingly, 75% of xylazine-positive patients were from the Northeast, with a significantly lower likelihood of detection in other regions. This finding underscores the regional prevalence of xylazine-adulterated fentanyl.
"Xylazine's presence in the Northeast is a growing concern," says senior author Dr. Alex Manini, Professor of Emergency Medicine. "Our study not only highlights this regional trend but also establishes a vital connection between xylazine exposure and decreased heart rate. This knowledge contributes to our understanding of the toxic effects of xylazine-fentanyl overdose and empowers emergency clinicians to enhance patient care."
The research team is now delving deeper into xylazine's impact on patient outcomes and its relationship with vital signs.
This study was made possible by funding from the National Institute on Drug Abuse and the Centers for Disease Control and Prevention.
About Mount Sinai Health System
Mount Sinai is a leading academic medical system in New York, employing 48,000 people across seven hospitals, over 400 outpatient practices, and numerous research and clinical labs. They are dedicated to tackling complex healthcare challenges, advancing scientific knowledge, and providing high-quality care to all.
Mount Sinai's integrated approach, combining hospitals, labs, and schools, offers comprehensive healthcare solutions from birth to old age. Their innovative methods, including AI and informatics, ensure patient-centric care. The system includes thousands of physicians and joint-venture centers, consistently ranking among the top hospitals in the U.S.
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