Fenfluramine

A serotonergic antiseizure medicine, FDA-approved for seizures of Dravet syndrome and Lennox-Gastaut syndrome in patients 2 years and older.

psilodex.org/m/fenfluramine · 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: ~20 h; Approximate, in adults. Source under Interaction below.

Named in state rules?

Not namedColorado Condition rules (3)

Not namedOregon

PendingNew Mexico

Cite asPsilodex, “Fenfluramine”, v2026.10.05. psilodex.org/m/fenfluramine

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

Seizures associated with Dravet syndrome
Seizures associated with Lennox-Gastaut syndrome

Sources [1]

Other safety

Boxed warning: valvular heart disease and pulmonary arterial hypertension, with echocardiograms before, during and after treatment under a restricted REMS program.

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

Sources [1]

01 Interaction with psilocybin

Not studied with psilocybin; it acts on the same serotonin receptors as psilocybin, so added or competing effects are possible.

Detail There are no psilocybin data for fenfluramine. Its label states that fenfluramine and norfenfluramine act at serotonin 5-HT2 receptors, the receptor family through which psilocin acts. So combined effects may add or interfere. Its label warns of serotonin syndrome with other serotonin-boosting drugs; none has been reported with psilocybin. Its label also warns of increased blood pressure, including rare hypertensive crisis (a dangerous spike). Psilocybin also briefly raises blood pressure and heart rate. Separately, its label lists somnolence (sleepiness) and suicidal thoughts (a warning for all antiepileptic drugs). Abrupt withdrawal can increase seizure frequency. Sources [1]

Human data with psilocybin: No psilocybin data; based on how it works and its label
Half-life: ~20 h (FDA label, checked 2026-10-04)

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

5 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]
Psychiatric reactions: The label or source warns of psychiatric effects such as psychosis, mania, hallucinations, suicidal thoughts or severe mood or behavior changes. Psilocybin can also bring up strong emotions, so these warnings are relevant to screening. 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 [1]

03 State rules

Plain-language summary · official text governs

CO4 CCR 755-1

Not namedCondition rules (3)

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

Screening items in state rules

This medication is usually taken for a condition. State rules screen for some conditions directly, so the medication is a prompt to ask about them. Confirm with the participant; never assume a condition from the medication.

Seizure disorder (usual indication)
- CO 2.5(A)(2) · Clinical Facilitator licensees
- CO 6.16(F)(2)(a) · Facilitators without a clinical facilitator license
- CO 6.16(F)(1) · All licensees

05 Sources

FINTEPLA (fenfluramine) oral solution (UCB) · FDA label (DailyMed) — Serotonergic: 5.7 "Serotonin syndrome, a potentially life-threatening condition, may occur with FINTEPLA, particularly with concomitant administration of FINTEPLA with other serotonergic drugs" | Raises blood pressure or heart rate: 5.8 "FINTEPLA can cause an increase in blood pressure" | Sedating or CNS depressant: 5.4 "FINTEPLA can cause somnolence, sedation, and lethargy." | Psychiatric reactions: 5.5 "Antiepileptic drugs (AEDs), including FINTEPLA, increase the risk of suicidal thoughts or behavior in patients taking these drugs for any indication." | Withdrawal or rebound if stopped abruptly: 5.6 "FINTEPLA should generally be withdrawn gradually because of the risk of increased seizure frequency and status epilepticus." | 12.1 "Fenfluramine and the metabolite, norfenfluramine, exhibit agonist activity at serotonin 5-HT2 receptors." | 12.3 "The elimination half-life of fenfluramine was 20 hours"

Record history

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

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