Harford County officials say a powerful veterinary sedative nicknamed "rhino tranq" is increasingly crashing the local fentanyl supply, turning already deadly doses into medical minefields for people who use drugs and the first responders trying to save them. The drug can trigger prolonged sedation, dangerously slow breathing, and a slowed heart rate, and officials warn that those symptoms can keep going even after naloxone is given.
Maj. Lee Dunbar of the Harford County Sheriff's Office told CBS Baltimore the sedative has "made its way" into Harford County and that patrol units seized two suspected samples last year. Ronya Nassar with the Harford County Department of Health told CBS Baltimore that county testing found positive medetomidine results in 17% of samples in late 2025 and 32% in the first quarter of 2026. Nassar urged bystanders to use naloxone and call 911, while stressing that naloxone will not reverse the sedative's non-opioid effects.
What Is 'Rhino Tranq'?
Medetomidine, better known on the street as "rhino tranq," is an alpha-2 adrenergic agonist used as a veterinary sedative and is not approved for human use. The Maryland Department of Health's Rapid Analysis of Drugs program has flagged medetomidine as an emerging adulterant in the state drug supply, a warning that lines up with troubling hospital reports. Federal health investigators have documented clusters of severe medetomidine-related prolonged sedation and withdrawal in patients, highlighting the clinical risks. According to an MMWR report from the CDC, clinicians have, in some cases, had to escalate care for affected patients.
Why Naloxone May Not Be Enough
Because medetomidine is not an opioid, naloxone (Narcan) can pull someone back from the fentanyl component but will not touch the tranquilizer's sedative punch. Health officials say rescuers should focus on the basics: keeping the airway open, providing rescue breathing, and calling 911 so advanced care can step in.
The Southern Nevada Health District's advisory underscores that this is not a quick in-and-out emergency. Providers may need frequent reassessment and early supportive care, and in severe cases may turn to treatment strategies that address alpha-2 agonists, including medications such as clonidine. The Southern Nevada Health District laid out clinical signs to watch for and treatment considerations in a February advisory.
Policy And Local Context
State lawmakers are already trying to clamp down on these veterinary sedatives. HB0417, a bill that would add medetomidine and xylazine to Maryland's controlled substances schedule, passed the House in early March and now sits in the Senate Finance Committee. Other parts of Maryland are seeing the same pattern. Wicomico County reported medetomidine in roughly 10% of tested samples, according to WBOC, a sign the adulterant is not confined to a single hotspot.
The problem is not unique to Maryland either. For a broader context, local alerts elsewhere have surfaced, including Bay Area warnings like Rhino Tranq Hits Berkeley. Legislative records from the Maryland General Assembly track HB0417's recent movement through the statehouse.
If you encounter a suspected overdose, use naloxone immediately, start rescue breathing, and call 911 so emergency responders can provide airway support and advanced care. For local information on naloxone, drug checking, and harm reduction services, visit the Maryland Department of Health's RAD and overdose prevention pages through the Maryland Department of Health.
