Baltimore Health Officials Issue Urgent Warning on Medetomidine, the 'Rhino Tranq' Invading Opioid Supply

Baltimore City Health Commissioner Dr. Michelle Taylor's office issued a stark advisory this week that signals a dangerous evolution in America's overdose crisis. Medetomidine—a veterinary sedative used to immobilize rhinoceroses and other large animals—has established itself as a persistent threat in Maryland's illicit drug supply, complicating overdose response and creating unprecedented withdrawal challenges for people who use opioids.

The warning arrives as public health officials across the Mid-Atlantic grapple with a substance that defies conventional intervention strategies. Unlike fentanyl, which can be reversed with naloxone, medetomidine operates through entirely different biological pathways, leaving even prepared responders struggling to save lives.

From Veterinary Clinics to City Streets

Medetomidine first appeared in Maryland's drug supply in July 2022, initially concentrated in Cecil County due to its proximity to Philadelphia. Since then, the substance has spread geographically and now registers in Baltimore City, Harford County, St. Mary's County, and Wicomico County. The sedative was detected in samples from the Penn-North neighborhood overdose cluster last October—a community still recovering from its central role in the 2015 Freddie Gray unrest and subsequent opioid devastation.

The numbers tell a story of rapid proliferation. According to CDC data released earlier this year, medetomidine detections surged 950 percent between 2023 and 2024, then rose an additional 215 percent in 2025. The drug now appears in 18 states and has reached all 20 CDC sentinel surveillance sites.

What makes medetomidine particularly alarming is its pharmacological profile. As an alpha-2 adrenergic agonist, the drug produces profound sedation, bradycardia, hypotension, and respiratory depression—but none of these effects respond to naloxone. When combined with fentanyl, which remains the dominant opioid in Baltimore's drug supply, medetomidine creates a dual-threat overdose scenario where standard reversal medication addresses only half the problem.

The Withdrawal Crisis Nobody Prepared For

Perhaps most concerning for treatment providers is medetomidine's withdrawal syndrome, which differs fundamentally from both opioid and xylazine withdrawal. Reports from Philadelphia, where the drug first gained prominence, describe a severe constellation of symptoms including dangerous hypertension, tachycardia, and violent vomiting that often requires intensive care unit management.

"Medetomidine withdrawal almost always occurs alongside opioid use disorder," explains the Baltimore advisory, emphasizing that clinicians must treat both conditions simultaneously rather than addressing them sequentially. The withdrawal can begin within hours of last use, catching patients and providers off guard with its intensity and medical complexity.

This withdrawal profile creates particular challenges for correctional facilities, where medication-assisted treatment access remains inconsistent. A recent STAT News investigation documented cases of inmates receiving only ibuprofen and Pepto-Bismol during medetomidine withdrawal—grossly inadequate interventions for a condition that can produce life-threatening cardiovascular instability.

New Protocols for First Responders

The Baltimore City Health Department's advisory includes specific guidance for clinicians and emergency responders encountering medetomidine-involved cases:

Assessment priorities have shifted. With medetomidine, responders must check breathing first, then responsiveness—a reversal of the traditional approach. The drug can leave individuals deeply sedated yet breathing adequately, creating a deceptive clinical picture where patients appear to be in immediate danger when they are stable, or conversely, seem stable when they are not.

Naloxone administration requires recalibration. The advisory stresses continuing to administer naloxone for suspected overdoses, as opioids are frequently co-present. However, responders should use the lowest effective dose to restore breathing and anticipate persistent sedation even after successful opioid reversal. Critically, naloxone administration will not trigger medetomidine withdrawal, since the sedative does not operate on opioid receptors.

Supportive care becomes essential. Medical providers must monitor vital signs closely and prepare for airway management and advanced cardiac life support. The prolonged sedation associated with medetomidine—sometimes lasting hours beyond fentanyl's effects—requires extended observation periods that strain already burdened emergency departments.

Community Adaptation and Harm Reduction

For community partners and people who use drugs, the advisory emphasizes several harm reduction strategies: never using alone, utilizing drug checking services where available, and seeking immediate medical care if severe vomiting, pounding headache, chest pain, or marked changes in blood pressure or heart rate appear after use.

Unlike xylazine, which produces distinctive necrotic wounds, medetomidine has not been associated with similar tissue damage. In fact, health officials have observed decreasing wound presentations in areas where medetomidine has replaced xylazine—a small silver lining in an otherwise concerning development.

Maryland's Overdose Response Programs can now order medetomidine test strips (MTS) to help people who use drugs identify the substance's presence before consumption. The state's Rapid Analysis of Drugs (RAD) program allows syringe service participants to submit paraphernalia samples for laboratory testing, with results typically available within a week.

A National Pattern with Local Consequences

Baltimore's warning reflects a broader national pattern as medetomidine establishes itself as the successor to xylazine—the veterinary tranquilizer that began appearing in fentanyl supplies in 2019 and now contaminates approximately 90 percent of Philadelphia's opioid supply. Where xylazine earned the street name "tranq," medetomidine has acquired the even more ominous moniker "rhino tranq" reflecting its original veterinary purpose.

The emergence of medetomidine illustrates a fundamental challenge in addressing synthetic drug markets: when regulators and public health systems develop responses to one threat, illicit manufacturers pivot to alternatives. Medetomidine, like xylazine before it, is not controlled under the Controlled Substances Act, though the DEA has proposed emergency scheduling for both substances.

For Baltimore—a city that has lost thousands of residents to overdose deaths in recent years—the medetomidine warning arrives at a particularly fraught moment. The city has made progress in reducing mortality through expanded naloxone distribution and harm reduction initiatives, but those gains depend on interventions that medetomidine partially neutralizes.

The Path Forward

The Baltimore City Health Department will host a training session on medetomidine intoxication and withdrawal management on June 22, targeting medical providers who increasingly encounter this unfamiliar substance. Similar trainings are proliferating across the Northeast and Midwest as the drug's geographic footprint expands.

Public health officials emphasize that despite medetomidine's challenges, the fundamental principles of overdose response remain unchanged: carry naloxone, use it promptly for suspected overdoses, and call emergency services. The sedative's presence complicates but does not eliminate the life-saving potential of timely intervention.

Yet the medetomidine crisis also underscores the limitations of a purely reactive approach to drug policy. As long as fentanyl dominates the illicit opioid market, adulterants will continue proliferating—each bringing new clinical challenges and requiring new adaptations from providers, responders, and people who use drugs.

For now, Baltimore's health department has issued its warning. The question is whether the broader system—treatment facilities, correctional institutions, emergency departments, and federal policymakers—can adapt quickly enough to prevent medetomidine from erasing the hard-won progress of recent years.