Research chemicalStimulantResearch chemicalSubstituted methamphetamine

4-Fluoromethamphetamine (4-FMA)

Also known as 4-FMA · para-fluoromethamphetamine

Written by enwyReviewed 4 Aug 20262 sources0 comments

4-Fluoromethamphetamine (4-FMA) is the para-fluoro analogue of methamphetamine, reported as a euphoric but harsh stimulant with a pronounced comedown. It is less favoured than 2-FMA. Human data is limited to anecdote and analytical reports.

01 Overview

4-FMA is a ring-fluorinated methamphetamine analogue. Compared with the 2-fluoro isomer, users describe more euphoria but a harsher body load, more anxiety and a heavier comedown, which has made it less popular among people seeking a functional stimulant.

No controlled human research exists. Its cardiovascular, psychiatric and neurotoxic risks are inferred from its close relationship to methamphetamine and remain unconfirmed in humans.

02 Mechanism

Releases and inhibits reuptake of dopamine, noradrenaline and, to a lesser extent, serotonin. The para-fluoro substitution is associated with somewhat greater serotonergic activity than the 2-fluoro isomer.

03 Dosing

Tier	Dose	Route	Notes
Common	15–40 mg	Insufflated	Faster, harsher; raises redosing and cardiovascular risk.
Light	20–40 mg	Oral	Anecdotal; harsher than 2-FMA at comparable doses.
Common	40–80 mg	Oral	More euphoric but heavier body load and comedown.

04 Effects

Effect	Magnitude	Evidence
Euphoria and stimulationMore euphoric than 2-FMA, with typical stimulant energy and wakefulness.	moderate-strong	Anecdotal
SociabilityIncreased talkativeness and confidence reported at moderate doses.		Anecdotal
Appetite suppressionReduced hunger during the active period.		Anecdotal

05 Side effects

Effect	Severity	Frequency	Evidence
Anxiety and harsh comedownAnxiety during use and a pronounced low-mood, fatigued comedown are commonly reported.	Moderate	Very common	Anecdotal
Compulsive redosingEuphoria and short-lived peak encourage repeated dosing.	Moderate	Common	Anecdotal
Cardiovascular strainTachycardia, hypertension and chest discomfort; harsh body load reported at higher doses.	Severe	Common	Unconfirmed

06 Legal status

Psychoactive Substances Act 2016

Production and supply prohibited. · as of Jan 2026

United States

Not federally scheduled by name

Possible analogue under the Federal Analogue Act. · as of Jan 2026

07 References

New psychoactive substances overviewEUDA (European Union Drugs Agency)

Fluoromethamphetamine isomers: analytical and pharmacological dataPubMed

08 Discussion0 comments

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This page is reference information, not medical advice. Doses and protocols are documented as they appear in the clinical literature and in practice — describing them is not a recommendation to use them. Countermeasures listed here are not a substitute for a physician. Legal status varies by jurisdiction and changes.