Phenelzine

Clinical contraindication: Absolute; The clinical literature treats the combination as contraindicated.
Best available evidence: Case reports; Also: other psychedelic.
Half-life: 11.6 h; Approximate, in adults. Detail in 01.

Named in state rules?

CONot named

ORNot named

NMPending

Cite asPsilodex: phenelzine · v2026.10.02

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

01 Interaction with psilocybin

CR · XP

One case report: psilocybin mushrooms taken during phenelzine (with nortriptyline) produced full effects and no serious adverse events (Barnett 2024). With LSD, chronic phenelzine (alone or with tranylcypromine) nearly abolished the response in both people interviewed (Bonson & Murphy 1996). MAO inhibition can raise blood pressure with psilocybin (see tranylcypromine); serotonin toxicity is theoretical, with no reported human case.

Human data with psilocybin: Case reports or surveys only
Common practice: Where discontinuation is considered, product labeling describes a washout of at least two weeks before starting a serotonergic drug. Any change is prescriber-managed.
Half-life: mean 11.6 h (single dose); 14 days off before serotonergic drugs per label (FDA label, checked 2026-09-30)

Evidence types on this record

CRCase reports or online surveys

XPHuman data with another classic psychedelic (e.g. LSD), not psilocybin; named in the text

02 Pharmacology relevant to psilocybin

3 listed · counted on reports

MAO inhibition: Inhibits monoamine oxidase, the enzyme that breaks down serotonin and other monoamines. MAO also helps clear psilocin, so it can change how strong and how long the psilocybin effect is, and it raises serotonin levels. Sources [1]
Raises blood pressure or heart rate: Raises blood pressure or heart rate. Psilocybin raises both for several hours, so the effects can add. Sources [1]
Serotonergic: Increases serotonin activity, for example by blocking its reuptake or releasing it. Psilocybin acts on serotonin receptors, so effects can add together. With antidepressant use, the psilocybin response can be weaker. Sources [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 2026-09-30

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 2026-09-30

04 Conditions to ask about

None linked

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

05 Sources

NARDIL ® (Phenelzine Sulfate Tablets, USP) · FDA label (DailyMed)
Preston CL (ed). Stockley’s Drug Interactions, 11th ed. Pharmaceutical Press, 2016., p. 1399
Barnett BS, Koons CJ, Van den Eynde V, et al. Hypertensive emergency secondary to combining psilocybin mushrooms, extended release dextroamphetamine-amphetamine, and tranylcypromine. J Psychoactive Drugs 2024;57(3):297–303.
Bonson KR, Murphy DL. Alterations in responses to LSD in humans associated with chronic administration of tricyclic antidepressants, monoamine oxidase inhibitors or lithium. Behav Brain Res 1996;73:229–233.

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