The veterinary sedative is spreading through North American drug markets and may be missed by most toxicology tests.
Medetomidine is an α2-adrenergic drug used in veterinary medicine. The review describes its spread through North American illicit drug markets and notes that most toxicology testing does not detect it. The drug is about 200 times more potent than xylazine and has different activity at some receptors, which may affect its effects and treatment.
The main clinical concern described is withdrawal rather than intoxication alone. Patients may develop autonomic dysregulation, intractable vomiting and encephalopathy, or altered brain function, and treatment often requires several α2-agonist medicines, including injected dexmedetomidine. The authors hypothesize that local prevalence and the amount of medetomidine in the drug supply help explain why severe withdrawal has appeared in some regions but not others.
What medetomidine does
The review reports that medetomidine has been used as an adulterant in illicitly manufactured opioids since 2022 and has spread through North American drug markets. It often evades standard toxicology testing. The authors describe medetomidine as roughly 200 times more potent than xylazine, with greater selectivity for α2 receptors and activity at imidazoline-1 receptors.
Intoxication can resemble that caused by other α2-agonist drugs, including sedation and bradycardia, or an unusually slow heart rate. The review identifies withdrawal as the dominant clinical problem. Reported features include autonomic dysregulation, intractable vomiting and encephalopathy, and cases frequently require intensive care. Treatment often involves multimodal α2-agonist therapy, with escalation to parenteral, or injected, dexmedetomidine. In regions where medetomidine is established, withdrawal-related encounters and hospital admissions have risen.
Why the drug matters
Medetomidine may be present in illicit opioids without being identified by most toxicology tests, making it harder to recognize the cause of a patient’s illness. Severe withdrawal can require intensive care and a treatment approach that combines addiction care with critical care.
The regional differences described in the review also matter for health systems responding to the drug supply. The authors say better prospective, multicenter research, a validated tool for measuring withdrawal and integrated addiction-critical care models are needed.
// Source
Current Addiction Reports · 2026 · DOI: 10.1007/s40429-026-00786-4
Authors: Kory London, Philip Durney, B. I. Hart, Ashish Thakrar, Dennis Goodstein, Alex J. Krotulski, Daniel Teixeira Silva, Joseph D’Orazio, Lara Carson Weinstein, Jeanmarie Perrone, Michael J. Lynch
Institutions: University of Pittsburgh, University of Pennsylvania, Temple University, Thomas Jefferson University Hospital, Harm Reduction Services, Cooper Medical School of Rowan University, Cooper University Health Care, Thomas Jefferson University, Washington Poison Center, Fredric Rieders Family Foundation
