"Xylazine, an alpha-2 receptor agonist, is used in veterinary medicine as a sedative and muscle relaxant; it is not approved for use in humans. However, reports of adulteration of illicit opioids with xylazine have been increasing in the United States (1–3). In humans, xylazine can cause respiratory depression, bradycardia, and hypotension (4). Typical doses of naloxone are not expected to reverse the effects of xylazine; therefore, persons who use xylazine-adulterated opioids are at high-risk for fatal overdose. Although some regions of the United States have reported increases in xylazine-involved deaths, xylazine was involved in <2% of overdose deaths nationally in 2019 (2,5). Most xylazine-involved deaths are associated with fentanyls, including fentanyl analogs (1,5)."
Chhabra, N., Mir, M., Hua, M. J., Berg, S., Nowinski-Konchak, J., Aks, S., Arunkumar, P., & Hinami, K. (2022). Notes From the Field: Xylazine-Related Deaths - Cook County, Illinois, 2017-2021. MMWR. Morbidity and mortality weekly report, 71(13), 503–504. doi.org/10.15585/mmwr.mm7113a3