This week, the NDEWS Weekly Briefing focuses on medetomidine, a alpha-2 adrenergic agonist traditionally used in veterinary medicine for sedation and analgesia. While most prevalent in the Northeast region of the US, this potent non-opioid sedative has been increasingly detected as an adulterant in the unregulated drug supply in other areas of the country via community drug checking, wastewater samples, and in law enforcement seizures of drugs. Ongoing discussions with members of the NDEWS Early Warning Network have confirmed similar trends.

Last month, the Centers for Disease Control and Prevention (CDC) and the White House Office of National Drug Control Policy (ONDCP) issued a joint Health Advisory in response to the nationwide increasing reports of medetomidine detection and a severe withdrawal syndrome associated with medetomidine exposure. The advisory is intended to inform and guide public health professionals, clinicians, laboratorians, and community members on recognizing and responding to harms associated with medetomidine.

Previous medetomidine-related NDEWS Briefings:
Issue 270: February 13, 2026

Issue 226: April 11, 2025

As always, we welcome your input.

From January 1, 2023 to April 30, 2026, there were 182 reported EMS encounters for nonfatal drug-related overdoses involving medetomidine (n=182) nationally. The demographic characteristics of the non-suppressed EMS encounters are shown below including age, sex, and race. Counts fewer than 10 encounters are suppressed.

Nonfatal drug-related EMS encounters involving medetomidine were included when the emergency response involved patient contact and the record contained a documented mention of medetomidine or “rhino tranq” (including common misspellings) in the patient complaint or narrative. Selected nonfatal encounters were classified using the CDC DOSE overdose syndrome, the Nonfatal Overdose syndrome, and the Substance Use Disorder composite syndrome. All dispatch types included follow the guidelines set by the National Emergency Medical Services Information System (NEMSIS).

Limitations: biospatial.io data reflect pre-hospital EMS encounters and do not include hospital outcomes, toxicology confirmation, medical history, or prescription information. Much of the data relies on clinical impressions, self-report, or bystander accounts. Additionally, EMS encounters for nonfatal drug-related overdoses involving medetomidine may be underreported, overreported or misclassified. biospatial.io syndromes and symptoms are not mutually exclusive. Click here to view the full report.

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Why are we reporting on this? Medetomidine has continued to appear in online discussions amid concerns about its presence as an adulterant in the unregulated opioid supply. Reddit discussions reveal concerning patterns regarding its role as a potent non-opioid sedative added to fentanyl. Although opioid overdose reversal medications like naloxone should still be administered (as opioids are involved in most medetomidine overdoses), medetomidine may complicate overdose response with commenters highlighting difficulty managing overdoses, in addition to severe life-threatening complications during withdrawal.

What is Medetomidine? Medetomidine is a potent alpha-2 adrenergic agonist traditionally used in veterinary medicine for sedation and analgesia. It has increasingly appeared as a highly potent illicit drug additive, serving as a replacement or companion to xylazine in fentanyl mixtures.

Previous NDEWS Web Monitoring Reports:
February 13, 2026
April 11, 2025
June 14th, 2024

Public Health Impacts: Reddit discussants report significant adverse effects associated with medetomidine exposure, including profound and sudden sedation, severe dry mouth, extreme dizziness upon standing, and intense hot flashes. Commenters frequently describe experiencing vivid, terrifying hallucinations and acute psychological distress shortly after administration. Multiple discussants note severe physiological complications such as extreme edema in the lower extremities that severely impairs mobility, acute gastrointestinal distress, and fluid retention around vital organs. Furthermore, abrupt cessation is reported to trigger complex withdrawal syndromes characterized by dangerously severe chest pains, heart palpitations, migraines, and intense 'brain zaps'.

How is it Being Discussed? Reddit commenters believe that medetomidine is rapidly spreading through the domestic drug supply, noting that it frequently adulterates fentanyl and heroin without the knowledge of consumers. There is frequent discussion regarding the challenges of detection, with discussants sharing experiences where substances tested negative on standard xylazine test strips but later proved positive for medetomidine through advanced drug checking methods like fourier-transform infrared spectroscopy and gas chromatography-mass spectrometry. Discussants actively seek advice on the accuracy of new rapid test strips to mitigate the long turnaround times of laboratory testing. The drug is consistently discussed in the context of minimizing harms associated with substance use, with commenters sharing the difficulties that outreach programs and medical staff face due to a widespread lack of clinical protocol for medetomidine withdrawal. The substance is discussed alongside other unregulated and/or alternative substances, including fentanyl analogs, xylazine, methadone, gabapentin, and kratom.

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A recently published brief report in Journal of Addiction Medicine by Hilton et al. analyzed 2017-2025 intensive care unit (ICU) data from two hospitals in Philadelphia, Pennsylvania, to assess how medetomidine’s emergence affected ICU use and opioid withdrawal costs, compared with the fentanyl-only and xylazine eras. Median quarterly ICU charges dramatically increased from ~$1.4 million (fentanyl-only) to $2.9 million (xylazine) and over $17 million after medetomidine. Quarterly admissions for opioid withdrawal also increased (~62 in the xylazine era vs. ~261 with medetomidine). Although medetomidine-related withdrawal requires more complex care, higher per-patient costs were not the main driver; instead, the surge in ICU admissions drove overall costs. These findings highlight a growing public health challenge requiring system-level responses, including resource reallocation. Read the full brief report here.

A study published earlier this year in the Harm Reduction Journal by Amate and Lieberman examined how well commercial test strips detect different forms of medetomidine. Researchers tested varying ratios of its two forms, dexmedetomidine (dex) and levomedetomidine (levo), as well as a racemic mixture (1:1 mix) to evaluate the accuracy of medetomidine and dexmedetomidine test strips (MTS) across different water types and temperature conditions. Results showed reduced reliability of MTS in hard water, performing best when soft or purified water was used, with decreased accuracy at higher temperatures (above 37 °C/98.6 °F). Test consistency also varied across brands and batches. Some strips detected only certain forms, while others produced false positives unless both were present. Test strips are a useful tool for drug checking, but differences in design and real-world conditions may limit reliablibility, making addressing medetomidine-related harms challenging. The authors recommend distributing purified water and standardized measuring tools alongside test strips to improve accuracy in overdose prevention settings. Read the full study here.

In November 2024, hospitals and behavioral health providers in Philadelphia, Pennsylvania reported severe, atypical withdrawal cases requiring intensive care unit (ICU) care, later linked to medetomidine. Drawing on first hand experience, University of Pennsylvania Health System physicians Chetok and Roder published an editorial in American Family Physician outlining recognition and management of medetomidine-related overdose and withdrawal. They emphasize adapting overdose response by administering naloxone followed by rescue breathing when medetomidine is suspected. Withdrawal presents rapidly, often within hours, peaking at 18-36 hours, and includes high blood pressure, tachycardia (fast heart rate), vomiting, and altered state of consciousness. Patients may shift quickly from sedation-related low blood pressure and bradycardia (slow heart rate) severe withdrawal symptoms, frequently requiring hospitalization or ICU care. Effective management of medetomidine withdrawal requires frequent monitoring, early initiation of alpha-2-agonist therapy, and long-acting opioid treatments. Read the full editorial here.

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Dear friends of NDEWS,

Have you ever been to a College on Problems of Drug Dependence meeting? If not, you are missing an opportunity to learn about drugs from the bench to the community. Many of us have made lifelong friends by attending the annual meeting. This year, the conference will be held on 13 - 17, 2026 in delightful Portland, Oregon! If you have never been before and want to learn more about the meeting and organization, click here.

Register for CPDD’s 88th Annual Meeting here.

We’d also love to see you at the Annual NDEWS Summit, which will be held as a hybrid event on Saturday, June 13 from 2:00–6:00 PM PT. While it is held in conjunction with CPDD, registration for the CPDD conference is not required to attend the NDEWS Summit.

Register for NDEWS Summit here.

📅 Date: Saturday, June 13, 2026

🕑 Time: 2:00 pm - 6:00 pm PT

📍 Location: In person at the Oregon Convention Center & Hyatt Regency Portland or virtually via Zoom.

We hope to see you there!

The NDEWS team

The NDEWS Weekly Briefing curates emerging data and findings from across the Early Warning Network, which includes three core components: our Scientific Advisory Group (SAG), comprised of national experts and federal partners; our Sentinel Site Directors (SSDs), who lead local surveillance in key geographic regions; and our Community-Based Health Experts, who provide on-the-ground insights from populations most impacted by drug trends. Together, these contributors generate timely, multidisciplinary and impactful information, ranging from peer-reviewed research findings to local surveillance data. These contributions inform public health and research communities.

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If you miss or want to learn more about NDEWS Original Content, you can find our archived content on the NDEWS website:

     • NDEWS Hotspot Alerts using substance-related EMS data
     • NDEWS Rapid Street Reporting (RSR) survey data reports
     • NDEWS Web Monitoring Team Reddit Alerts
     • NDEWS Sentinel Site Reports
     • Previous issues of the NDEWS Weekly Briefings

The Weekly Briefing is a newsletter published each week by the National Drug Early Warning System (NDEWS) Coordinating Center, which is funded by the National Institute on Drug Abuse (U01DA051126) to the University of Florida (MPI: Cottler (contact), Co-Is: Goldberger, Nixon, Striley), NYU Langone Health (MPI: Palamar), and Florida Atlantic University (Co-I: Barenholtz).Any item may be reproduced provided the source is acknowledged.