Nalmefene (nasal spray, injection)

A long-acting opioid blocker given as a nasal spray or injection for emergency treatment of known or suspected opioid overdose.

psilodex.org/m/nalmefene-injection-nasal · data v2026.10.05

Clinical contraindication: None listed; No label contraindication covering psilocybin was found. This is not a finding that the combination has been shown to be without risk.
Psilocybin evidence: No psilocybin data
Half-life: ~9–11 h; Approximate, in adults. Source under Interaction below.

Named in state rules?

Not namedColorado

Not namedOregon

PendingNew Mexico

Cite asPsilodex, “Nalmefene (nasal spray, injection)”, v2026.10.05. psilodex.org/m/nalmefene-injection-nasal

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

What it is used for

FDA status

FDA-approved

FDA-approved for

Emergency treatment of known or suspected opioid overdose (adults and children 12 and older)

Sources [1][2]

Other safety

In people physically dependent on opioids it can precipitate opioid withdrawal, including fast heart rate, fever, sweating, vomiting and increased blood pressure.

About the medication itself, separate from any interaction with psilocybin.

Sources [1]

01 Interaction with psilocybin

Not studied with psilocybin, and no mechanism linking them has been described. Separately, it can trigger sudden withdrawal in people dependent on opioids.

Detail Nalmefene has no known interaction with psilocybin. It blocks opioid receptors and lasts longer than naloxone (half-life about 9–11 h). Separately, in people who are physically dependent on opioids, it may precipitate withdrawal. This withdrawal includes fast heart rate and increased blood pressure. Sources [1]

Human data with psilocybin: No psilocybin data; based on its label
Half-life: ~9–11 h (FDA label, checked 2026-10-04) 11.4 h after 2.7 mg nasal spray (Opvee); 9.07 h after Zurnai auto-injector.

Evidence types on this record

No psilocybin dataNo psilocybin data: no human data with psilocybin or another classic psychedelic; the text draws on the medication's own pharmacology and its label or reference facts

02 Pharmacology relevant to psilocybin

1 listed · counted on reports

Opioid blocker: Blocks opioid receptors. It can trigger sudden withdrawal in someone taking opioids, and after it wears off, a usual opioid dose can cause overdose. Sources [1][2]

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 2026-10-04

OROAR 333-333

Not named

No provision names this medication or its class.

Oregon · checked 2026-10-04

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 2026-10-04

04 Conditions to ask about

None linked

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

05 Sources

OPVEE (nalmefene hydrochloride) nasal spray (Indivior) · FDA label (DailyMed) — Opioid blocker: 12.1 "OPVEE is an antagonist at opioid receptors." | 5.3 "The use of OPVEE in patients who are opioid dependent may precipitate opioid withdrawal" "tachycardia" "increased blood pressure" | "plasma concentrations have a terminal elimination half-life of 11.4 (%CV 20.8) hours"
ZURNAI (nalmefene hydrochloride) injection auto-injector · FDA label (DailyMed) — Opioid blocker: 12.1 "ZURNAI is an antagonist at opioid receptors." | "plasma concentrations have a terminal elimination half-life of 9.07 (%CV 26.2) hours"
Halman A, Kong G, Sarris J, Perkins D. Drug–drug interactions involving classic psychedelics: a systematic review. J Psychopharmacol 2024;38(1):3–18. — no reported interaction
Sarparast A, Thomas K, Malcolm B, Stauffer CS. Drug-drug interactions between psychiatric medications and MDMA or psilocybin: a systematic review. Psychopharmacology 2022;239(6):1945–1976. — no reported interaction

Record history

v2026.10.02First published.
2026-10-04Last reviewed against its sources.

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