Xylazine: An Increasingly Frequent Adulterant in Fentanyl Street Drugs

Xylazine — a U.S. FDA-approved veterinary sedative used since the 1970s — is a centrally acting α₂-agonist (in the same class of drugs as dexmedetomidine [Precedex], clonidine, and tizanidine) that is increasingly prevalent in illicitly manufactured fentanyl in the U.S. Several overviews of xylazine's clinical effects and its emerging threat have been published recently in major journals (N Engl J Med 2023; 388:2209; Ann Intern Med 2023; 176:1370); here we provide a quick synopsis.

Xylazine was detected in only a small proportion (2%) of fentanyl overdoses in the late 2000s and early 2010s, but it has been detected increasingly in illicitly manufactured fentanyl powder (23% of seized samples) and fentanyl pills (7% of seized samples) in the …