Health officials finding different illicit veterinary sedative in US drug supply

Illicit medetomidine bulk powder has emerged as a dangerous adulterant in the U.S. illegal drug supply, often mixed with other illicit drugs such as fentanyl or heroin.

First identified in Maryland in 2022, illicit medetomidine bulk powder quickly spread to California, Colorado, Illinois, Missouri, and Pennsylvania, culminating in overdose clusters in Chicago, Philadelphia, and Pittsburgh, by early 2025, according to the findings in the Centers for Disease Control and Prevention’s May 1 edition of the Morbidity and Mortality Weekly Report.

Medetomidine is approved by the Food and Drug Administration (FDA) for dogs for sedation and analgesia and can be used under extra label drug use regulations for cats, pocket-pets, exotics, zoo and wildlife species for restraint and sedation. FDA-approved pharmaceuticals with medetomidine as the active ingredient have not been implicated.

Medetomidine, a racemic mixture of dexmedetomidine and levomedetomidine, is not a controlled substance, nor is it approved for human use. However, the dexmedetomidine enantiomer is considered the pharmacologically active component responsible for medetomidine’s sedative and analgesic effects. Dexmedetomidine has separate FDA approvals for use in animals and in humans. In humans, it is often used for sedation in intensive care unit (ICU) patients.

Over a seven-day period in May 2024 in Chicago, 181 suspected opioid overdoses were reported in just three hospitals. Of these, 12 were confirmed illicit medetomidine-involved cases, and most exhibited a slow heart rate, altered mental status, and a poor response to naloxone, the standard opioid overdose reversal agent.

In Philadelphia, between September 2024 and January 2025, 165 people were hospitalized with a previously unseen withdrawal syndrome now linked to illicit medetomidine. Most patients required ICU visits, and nearly a quarter were intubated. While traditional opioid withdrawal treatments failed, dexmedetomidine, proved effective in controlling symptoms given the drug’s similar pharmacological properties to medetomidine.

It was a similar story with nearly two dozen patients evaluated between October 2024 and March 2025 in Pittsburgh. Ten were confirmed to have illicit medetomidine exposure. Most deteriorated rapidly after arriving at the hospital, with symptoms of extreme autonomic hyperactivity, including tachycardia, hypertension and agitation. Nine of the 10 required ICU admission. Once again, all responded to dexmedetomidine when other medications failed.

Illicit medetomidine’s rapid emergence as an adulterant in the illegal drug supply has some public health officials calling for action now. “Medetomidine, an α2-adrenergic receptor agonist approved exclusively for veterinary use, has increasingly been implicated in illicit fentanyl-related overdoses,” stated a commentary in an April 2025 edition of “The Lancet.” “Its high potency—200- to 300-fold greater than xylazine—and rapid geographic spread underscore the need for heightened clinical vigilance and coordinated interventions.”

“The burgeoning medetomidine overdose crisis demands coordinated actions from clinicians, public health agencies, and policymakers,” the article continues. “The tools for an effective response are within reach: developing medetomidine-specific clinical guidelines, expanding epidemiological surveillance, and fostering multi-sectoral collaborations. However, their success hinges upon our collective resolve to implement them.”