University of Wisconsin–Madison Medical College of Wisconsin

Epidemiology of Xylazine-Positive Fatal Overdoses in Milwaukee County, Wisconsin, 2019-2023

Max Mantych, MS; Cassandra Laibly, MS; Hunter Russell; Kirsten M.M. Beyer, MS, PhD; Yuhong Zhou, MS, PhD, ME; Ronald Anguzu, MD, PhD

WMJ. 2025;124(2): 148-152

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ABSTRACT

Introduction: Xylazine association with fentanyl poses an emerging threat to public health. We conducted a retrospective study to analyze xylazine-related fatal overdoses in Milwaukee County, Wisconsin from 2019 through 2023.

Methods: Using medical examiner data, we compared fatal xylazine overdoses (n = 243) with fentanyl overdoses without xylazine (n = 1946). Demographic, polysubstance, temporal, and geographic characteristics were analyzed.

Results: Xylazine fatalities have surged since 2019, exhibiting different polysubstance profiles than fentanyl overdoses without xylazine. We identified 8 geospatial clusters contributing to 64% of xylazine overdoses.

Discussion: We encourage localized interventions to address the xylazine-fentanyl syndemic. Policy measures such as Wisconsin Act 217, which legalized xylazine testing materials, promote evidence-based harm reduction tools to mitigate the risks associated with xylazine’s increasing prevalence in the Midwest.


Author Affiliations: Graduate School, Medical College of Wisconsin (MCW), Milwaukee, Wisconsin (Mantych, Laibly); Milwaukee County Medical Examiner’s Office, Milwaukee, Wisconsin (Russell); Division of Epidemiology, Institute for Health and Equity, MCW, Milwaukee, Wisconsin (Beyer, Zhou, Anguzu); Center for Advancing Population Sciences, MCW, Milwaukee, Wisconsin (Beyer, Anguzu).
Corresponding Author: Max Mantych, MS, 8701 W Watertown Plank Rd, Milwaukee, WI 53226; email mmantych@mcw.edu; ORCID ID 0009-0005-4641-6751
Financial Disclosures: None declared.
Funding/Support: None declared.
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