4-FA (4-fluoroamphetamine)

An amphetamine-type stimulant designer drug (4-fluoroamphetamine) with MDMA-like effects, used recreationally; not FDA-approved for medical use.

psilodex.org/m/4-fluoroamphetamine · 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: ~8–9 h; Approximate, in adults. Source under Interaction below.

Named in state rules?

Not namedColorado

Not namedOregon

PendingNew Mexico

Cite asPsilodex, “4-FA (4-fluoroamphetamine)”, v2026.10.05. psilodex.org/m/4-fluoroamphetamine

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

Availability

Unregulated novel psychoactive substance; not FDA-approved

01 Interaction with psilocybin

Not studied with psilocybin; this stimulant strongly raises blood pressure and heart rate, so adding to psilocybin's own rises is possible.

Detail 4-Fluoroamphetamine (4-FA) is an amphetamine-type stimulant with serotonin effects. In a controlled human study, it strongly raised blood pressure for 4–5 hours, followed by a sustained heart-rate rise (de Sousa Fernandes Perna 2018). Emergency cases show higher blood pressure than with MDMA or amphetamine (Gresnigt 2022). Six deaths followed 4-FA combined with 25C-NBOMe, a potent 5-HT2A agonist that acts at the receptor psilocybin works through (Gerostamoulos 2023). It has not been studied with psilocybin; its blood pressure and heart-rate rises may add to psilocybin's. Sources [1][2][3][6]

Human data with psilocybin: No psilocybin data; based on how it works
Half-life: ~8–9 h (article, checked 2026-10-04) Marked variation (5.5–16.8 h) after 100 mg oral in 12 volunteers.

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

2 listed · counted on reports

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 [3][4]

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

de Sousa Fernandes Perna EB, Theunissen EL, Dolder PC, et al. Safety profile and neurocognitive function following acute 4-fluoroamphetamine (4-FA) administration in humans. Front Pharmacol 2018;9:713. — Raises blood pressure or heart rate: Abstract "Overall, 4-FA produced a strong elevation in blood pressure up until 4-5 h after administration that was followed by a sustained increase in heart rate."
Gresnigt FMJ, Snik A, Franssen EJF, et al. 4-Fluoroamphetamine (4-FA) intoxication results in exaggerated blood pressure effects compared to MDMA and amphetamine: a retrospective analysis. J Am Coll Emerg Physicians Open 2022;3(5):e12813. — Abstract: "Severe 4-FA-related cardiovascular complications occurred in 40% of mono-intoxications."
Gerostamoulos D, Glowacki L, Pricone M, et al. Fatal intoxications from a combination of 4-fluoroamphetamine and 25C-NBOMe. J Anal Toxicol 2023;47(2):191–196. — Serotonergic: Abstract "These cases illustrate a possible increased risk of sudden death with this combination of drugs, both of which can elevate serotonin concentrations as well as act as strong stimulants."
Luethi D, Walter M, Zhou X, et al. Para-halogenation affects monoamine transporter inhibition properties and hepatocellular toxicity of amphetamines and methcathinones. Front Pharmacol 2019;10:438. — Serotonergic: Abstract "The selectivity of the compounds to inhibit the dopamine versus serotonin transporter decreased with increasing size of the para-substituent, resulting in potent serotonin uptake inhibition for the halogenated derivatives."
Toennes SW, Schneider D, Pogoda W, et al. Pharmacokinetic properties of 4-fluoroamphetamine in serum and oral fluid after oral ingestion. Drug Test Anal 2019;11(7):1028–1034. — Abstract "The elimination half-life was approximately 8-9 hours and shorter than that of amphetamine but it exhibited a marked variation (5.5-16.8 hours)."
Kuypers KPC, De Sousa Fernandes Perna EB, Theunissen EL, et al. A first-in-man study with 4-fluoroamphetamine demonstrates it produces a mild psychedelic state. J Psychoactive Drugs 2019;51(3):225–235. — Abstract: "It is concluded that while the 4-FA-induced psychedelic state is mild in intensity and in between that produced by amphetamine and MDMA as hypothesized"

Record history

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

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