4-Fluoroamphetamine (4-FA)
4-Fluoroamphetamine (4-FA) is a fluorinated amphetamine used recreationally as a stimulant with mild entactogenic qualities, sitting between amphetamine and MDMA in subjective profile. Human data is limited to surveys, poisoning case reports and small pharmacology studies; it has been associated with cardiovascular events including haemorrhagic stroke.
01 Overview
4-FA (4-fluoroamphetamine) is a ring-fluorinated analogue of amphetamine that gained popularity in the Netherlands and elsewhere in the 2010s, partly marketed as a shorter-acting, milder alternative to MDMA. Users report stimulation, mood elevation and mild empathogenic effects, with a comedown resembling that of amphetamines.
Evidence in humans is thin: it derives mainly from user surveys, emergency-department case series and a small number of controlled pharmacology studies. A cluster of severe cardiovascular events — including haemorrhagic and ischaemic stroke and cardiac complications — prompted regulatory review in several European countries. Long-term safety and neurotoxicity remain uncharacterised.
02 Mechanism
Acts as a releasing agent and reuptake inhibitor of dopamine, noradrenaline and serotonin. The 4-fluoro substitution shifts the monoamine balance relative to amphetamine, adding modest serotonergic (entactogen-like) activity.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Common | 30–70 mg | Insufflated | Insufflation reported as harsh; faster onset, shorter duration. |
| Light | 40–75 mg | Oral | Anecdotal ranges from user reports; no clinical dosing guidance exists. |
| Common | 75–125 mg | Oral | Duration commonly reported 4-6 hours. |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Stimulation and increased energyWakefulness, motivation and physical energy typical of amphetamines. | moderate-strong | Anecdotal | |
| Mood elevation and mild empathyUsers describe euphoria with a mild MDMA-like warmth, weaker than MDMA itself. | Anecdotal | ||
| Appetite suppressionReduced hunger during the active period, common to stimulants. | Anecdotal |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Comedown and mood disturbanceFatigue, low mood, anxiety and irritability in the hours to days after use. | Moderate | Very common | Anecdotal | |
| Compulsive redosingUrge to redose as effects fade, increasing total dose and cardiovascular exposure. | Moderate | Common | Anecdotal | |
| Cardiovascular strainTachycardia, hypertension and chest pain; case reports link 4-FA specifically to haemorrhagic and ischaemic stroke. | Severe | Common | Observational |