Medetomidine at a glance: schedule, half-life, and class
- Drug class
- Alpha-2 adrenergic agonist sedative
- Approved use
- Veterinary sedation (Domitor); its active half, dexmedetomidine, is approved for people as Precedex and Igalmi
- US legal status
- Not federally controlled (as of 2026)
- How it appears
- Mixed into illicit fentanyl
- Potency
- Much more potent than xylazine
- Naloxone
- Does not reverse it, but reverses fentanyl
- Withdrawal
- Severe high blood pressure, fast heartbeat, agitation
What is medetomidine?
Medetomidine is used by veterinarians to sedate animals. Dexmedetomidine, one of its two mirror-image forms, is approved for sedation in intensive care.[1]
Medetomidine replaced xylazine as the most common adulterant in Philadelphia's opioid supply in the last months of 2024, and has since been reported in many states.[1]
Medetomidine effects and how long they last
Medetomidine causes deep sedation, a slow heartbeat, and low blood pressure that can last hours. Mixed with fentanyl, people may stay unresponsive even after naloxone restores breathing.[1]
Medetomidine side effects and risks
Prolonged sedation and slow heartbeat: dangerously slow heart rate and low blood pressure.[1]
Severe withdrawal: people exposed daily have developed severe withdrawal with very high blood pressure, fast heartbeat, vomiting, tremor, and agitation, often needing intensive care.[1][2]
Overdose with opioids: naloxone reverses the fentanyl but not the medetomidine.
Warning: Give naloxone to anyone who may be overdosing on fentanyl, even if medetomidine is suspected. If breathing returns but the person stays sedated, keep them on their side and call 911.
Medetomidine interactions: what is dangerous to mix with it
Choose what it would be combined with:
| Combined with | What happens | Guidance |
|---|---|---|
| Fentanyl and other opioids | Deep, prolonged sedation; stopped breathing | Dangerous |
| Benzodiazepines and alcohol | Deeper sedation | Dangerous |
| Blood pressure medicines and beta blockers | Very slow heartbeat, low blood pressure | High risk |
This is not a full list. Combining substances raises the risk of harm, especially when the contents of street drugs are unknown.
Medetomidine overdose: signs and what to do
Overdose causes deep sedation, a very slow heartbeat, low blood pressure, and, with fentanyl, slowed breathing. Naloxone reverses the opioid part only.[1]
If someone may have overdosed
- Call 911 if the person is unresponsive, cannot be woken, has blue or gray lips, or is breathing slowly or not at all.
- Give naloxone (Narcan or a generic nasal spray, sold without a prescription) into one nostril. If there is no response after 2 to 3 minutes, give another dose.
- If you are trained, give rescue breaths. Otherwise place the person on their side so they do not choke.
- Stay with them. Naloxone can wear off before medetomidine does, so the overdose can return even after the person wakes up.
- Most states have Good Samaritan laws that protect people who call 911 for an overdose from some drug charges.
Medetomidine withdrawal timeline: symptoms and how long it lasts
Medetomidine withdrawal is a newly recognized, life-threatening syndrome among people exposed to it in fentanyl. It does not respond well to the usual opioid withdrawal treatments.[1][2]
- HoursRapid onsetRestlessness, anxiety, tremor, vomiting, and sweating.
- Day 1 to 3PeakVery high blood pressure, fast heartbeat, agitation, and confusion; many patients need intensive care.
- Days to a weekResolvesWith treatment, usually including dexmedetomidine, symptoms ease.
Warning: Medetomidine withdrawal can be life-threatening. Anyone with severe vomiting, agitation, chest pain, or very high blood pressure after stopping should go to an emergency department.
Hospitals have treated it with dexmedetomidine infusions, clonidine or guanfacine, and treatment for opioid use disorder.
Is medetomidine legal in the US? Schedule and legal status
Medetomidine is not a federally controlled substance. It is an FDA-approved veterinary drug, and diversion is not tracked by the DEA.[3]
- State action: some states, including Pennsylvania, have proposed adding it to their controlled substance schedules.
Where can someone get help with medetomidine use?
- SAMHSA National Helpline: 1-800-662-4357. Free, confidential, 24 hours a day, in English and Spanish. It gives referrals to local treatment and support.[4]
- FindTreatment.gov: a federal locator for state-licensed treatment programs, searchable by location, payment, and type of care.[5]
- 988 Suicide and Crisis Lifeline: call or text 988 for a mental health or substance use crisis.
- Your own clinician: a primary care doctor can screen, treat, and refer, and can discuss medicines that support recovery where they exist.
Medetomidine legal status in other countries
| Country | Status |
|---|---|
| International | Not under UN control |
Laws change and differ in detail. Check current rules before carrying any controlled medicine across a border.[6]
Common questions about medetomidine
What is rhino tranq?
A street name for medetomidine, a veterinary sedative mixed into fentanyl.
Does naloxone reverse medetomidine?
No, but it reverses the fentanyl it is usually mixed with, so always give it.
Is medetomidine worse than xylazine?
It is more potent, and its withdrawal can be severe and life-threatening.
Can medetomidine withdrawal kill?
It can cause dangerous blood pressure and heart rate spikes that need intensive care.
Is medetomidine a controlled substance?
Not federally, as of 2026.
Sources
- Notes from the Field: Suspected Medetomidine Withdrawal Syndrome Among Fentanyl-Exposed Patients, Philadelphia, Pennsylvania, September 2024 to January 2025. Centers for Disease Control and Prevention, MMWR, 2025.
- Notes from the Field: Severe Medetomidine Withdrawal Syndrome in Patients Using Illegally Manufactured Opioids, Pittsburgh, Pennsylvania. MMWR, 2025.
- Medetomidine Emerging as a Significant Adulterant in Indiana. US Drug Enforcement Administration, July 2026.
- National Helpline. Substance Abuse and Mental Health Services Administration.
- FindTreatment.gov. Substance Abuse and Mental Health Services Administration.
- International drug control conventions. United Nations Office on Drugs and Crime.
