Medetomidine ("rhino tranq")

A veterinary sedative (alpha-2 agonist) now found as an adulterant in illicit fentanyl; FDA-approved only for animals. Its relative dexmedetomidine is approved for humans.

psilodex.org/m/medetomidine · data v2026.10.04

Clinical contraindication: None listed; No clinical contraindication identified.
Psilocybin evidence: No psilocybin data
Half-life: Not stated in label or references

Named in state rules?

Not namedColorado

Not namedOregon

PendingNew Mexico

Cite asPsilodex, “Medetomidine ("rhino tranq")”, v2026.10.04. psilodex.org/m/medetomidine

Clinical data and state rules are separate facts. Both are shown; neither is a decision.

What it is used for

FDA status

Not FDA-approved

FDA-approved only for veterinary use (e.g. Domitor) as a sedative, analgesic or preanesthetic; not approved for humans. Its relative dexmedetomidine is approved for human use in intensive care and procedures.

Availability

Illicit

Sources [4]

01 Interaction with psilocybin

No psilocybin data; animal sedative in street fentanyl; its low heart rate and blood pressure naloxone does not reverse; withdrawal can cause high blood pressure.

Detail Veterinary alpha-2 sedative, more potent and longer-acting than xylazine, now found in illicit fentanyl; fentanyl is almost always also involved. It causes slow heart rate, low blood pressure and prolonged sedation that naloxone does not reverse, though naloxone reverses the fentanyl. Withdrawal can bring severe hypertension, fast heart rate and vomiting within hours, peaking 18–36 hours after last use. Sources [1][3][4]

Human data with psilocybin: None known: no published human data with psilocybin

Evidence types on this record

No psilocybin dataNo psilocybin data; record based on general references (product label, reference works, reviews)

02 Pharmacology relevant to psilocybin

3 listed · counted on reports

Sedating or CNS depressant: Slows the central nervous system: drowsiness, slower reactions and impaired coordination, and slowed breathing at high doses. Effects add with other sedating substances. Sources [1]
Withdrawal or rebound if stopped abruptly: Stopping suddenly can cause withdrawal or a rebound of symptoms. Sources [1][2]
Lowers blood pressure or causes orthostasis: Lowers blood pressure, or causes a drop on standing (orthostasis) that can bring dizziness or fainting. Sources [1]

03 State rules

Plain-language summary · official text governs

CO4 CCR 755-1

Not named

No provision names this medication or its class.

Colorado · checked 2026-09-30

OROAR 333-333

Not named

No provision names this medication or its class.

Oregon · checked 2026-09-30

NM7.35.3 NMAC (proposed)

Pending

New Mexico's clinical rules (proposed 7.35.3 NMAC) are not final. No provision naming this medication has been found.

New Mexico · checked 2026-10-02

04 Conditions to ask about

None linked

No condition named in state rules is linked to this medication.

05 Sources

Centers for Disease Control and Prevention. Medetomidine in the U.S. illegal fentanyl supply increasing risk for overdose and severe withdrawal syndrome. Health Alert Network HAN-00527, April 2, 2026. — alpha-2 agonist more potent and longer-acting than xylazine; bradycardia, hypotension, prolonged sedation; withdrawal with tachycardia and severe hypertension peaking 18–36 h
Huo S, London K, Murphy L, et al. Notes from the field: suspected medetomidine withdrawal syndrome among fentanyl-exposed patients — Philadelphia, Pennsylvania, September 2024–January 2025. MMWR 2025;74:266–268. — suspected medetomidine withdrawal syndrome, Philadelphia; 165 patients
US Drug Enforcement Administration. 2025 National Drug Threat Assessment. May 2025. — xylazine veterinary-only; 'rhino tranq' medetomidine 200–300x xylazine potency (pp. 30–32)
DEA Diversion Control Division. Medetomidine (including dexmedetomidine) fact sheet, March 2026.

Record history

v2026.10.02First published.
2026-10-03Last reviewed against its sources.

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