Research chemicalCathinoneStimulantResearch chemical

Flephedrone (4-FMC)

Also known as Flephedrone · 4-FMC · 4-Fluoromethcathinone

Written by enwyReviewed 4 Aug 20262 sources0 comments

Flephedrone (4-fluoromethcathinone) is the 4-fluoro analogue of methcathinone, a stimulant research chemical that circulated in the early 2010s grey market. It has a coarser, more purely stimulant profile than mephedrone and essentially no human safety data beyond case reports.

01 Overview

Flephedrone (4-FMC) is a ring-fluorinated cathinone that appeared as a designer stimulant alongside the broader mephedrone wave. Users describe a stimulant-forward experience with limited euphoria and a harsh, jittery character, often with unpleasant vasoconstriction.

No controlled human trials exist. The compound is documented through seized-material analysis, non-clinical pharmacology, and scattered intoxication reports, and it has been scheduled across many jurisdictions as part of blanket cathinone controls.

02 Mechanism

Functions as a monoamine reuptake inhibitor and releaser with a dopamine/noradrenaline-weighted profile, producing predominantly stimulant rather than entactogenic effects.

03 Dosing

Tier	Dose	Route	Notes
Common	30–90 mg	Insufflated	Reported as harsh and strongly vasoconstrictive.
Light	40–80 mg	Oral	Anecdotal only.
Common	80–150 mg	Oral	User-reported range.

04 Effects

Effect	Magnitude	Evidence
StimulationEnergy, wakefulness and drive, more stimulant than empathogenic.		Anecdotal
Increased focusShort-lived heightened attention reported by some users.		Anecdotal
Mild euphoriaModest mood lift, generally weaker than mephedrone.		Anecdotal

05 Side effects

Effect	Severity	Frequency	Evidence
Compulsive redosingBrief effects and dopaminergic reward drive rapid repeated dosing.	Moderate	Near-universal in binges	Anecdotal
ComedownAnxiety, irritability, fatigue and insomnia after the session.	Moderate	Near-universal	Anecdotal
Cardiovascular strainMarked tachycardia, hypertension and vasoconstriction reported.	Severe	Common	Observational
Unknown neurotoxicityNo data on long-term neurological consequences.	Severe	Unknown	Unconfirmed

06 Legal status

Germany

NpSG / BtMG

as of Jan 2026

United Kingdom

Class B

Generic cathinone control. · as of Jan 2026

United States

Schedule I (cathinone analogue)

Prosecutable under the Federal Analogue Act. · as of Jan 2026

07 References

Flephedrone (4-fluoromethcathinone) toxicology reportsPubMed

EUDA — synthetic cathinones drug profileEuropean Union Drugs Agency

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.