Emergence of Medetomidine in the Unregulated Drug Supply and Its Association With Hallucinogenic Effects.
Drug and alcohol review November 1, 2025 Adams L Sibley, Madigan L Bedard, Samuel Tobias et al.
Medetomidine, a veterinary tranquilizer more potent than xylazine, has emerged as an adulterant in the U.S. illicit fentanyl supply. Analysis of 11,363 drug samples from a national mail-based drug checking program between December 2022 and April 2025 found medetomidine in 2.4% of samples, with growth beginning June 2024. It commonly appeared with fentanyl (58.8%) and xylazine (55.9%). Samples where medetomidine was the primary ingredient were nearly 12 times more likely to be associated with reported hallucinations (17.6%) compared to all other samples (1.2%). These unexpected hallucinations may serve as a signal for medetomidine's presence in local drug markets, contradicting its clinical use for preventing delirium.