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    🧪 This is a research chemical with limited data on its long-term health effects, toxicity profile, and safe dosage ranges.

    4-FA

    Aliases: Pfa, Rdj, Flux, 4-fmp, Pal-303, 4-Fluoroamphetamine, 4fa

    Psychedelic Stimulant Empathogen Research-chemical

    Summary TheDrug.Wiki Erowid TripSit PsychonautWiki

    4-Fluoroamphetamine (also known as 4-FA, 4-FMP, para-Fluoroamphetamine, PAL-303 and colloquially as Flux) is a novel synthetic amphetamine compound that produces a unique progressive mixture of entactogenic and stimulant effects when administered. It is part of a series of fluorinated amphetamine analog that initially included such compounds as 2-FA, 2-FMA, and 3-FA. Anecdotal reports have described the subjective effects of 4-FA as having a moderate MDMA-like entactogenic onset for the initial few hours of the experience that then gradually transitions into traditional amphetamine-type stimulation (for a total duration of around 6 to 8 hours) with residual effects that can last a few hours afterward.

    Dose Information TheDrug.Wiki TripSit PsychonautWiki

    ROA Light Common Strong Heavy
    Oral 40-100mg 100-130mg 130-150mg 150mg+
    Light Common Strong Heavy

    Onset, Duration & After-effects TheDrug.Wiki TripSit PsychonautWiki

    ROA Onset Comeup Peak Offset After Effects Total
    Oral 30-60 min 30-75 min 2.5-3.5 hrs 2-3 hrs 6-12 hrs 5.5-8.8 hrs
    Insufflated 2-10 min 15-30 min 2-3 hrs 2-3 hrs 6-12 hrs 4.3-6.7 hrs

    Effect Profile

    75 reports

    Scores (1–10) curated from multiple sources:

    • Effect keyword matching from PsychonautWiki catalog
    • Validated against 57 Erowid trip reports
    • Weighted by importance: core (×3), major (×2), minor (×1)

    Full methodology

    Psychedelic 6.1
    Strong 6/10

    Strong auditory effects and body load with moderate visuals and headspace

    Visual Intensity ×3
    7
    color enhancement pattern recognition enhancement
    Headspace Depth ×3
    6
    thought connectivity time distortion confusion
    Auditory Effects ×1
    10
    auditory distortion auditory hallucination
    ⚠ Body Load / Somatic Effects ×1
    10
    temperature regulation suppression teeth grinding bruxism increased heart rate sweating
    Empathogen 10.0
    Extreme 10/10

    Strong empathy, euphoria, stimulation, and sensory enhancement

    Empathy / Social Openness ×3
    10
    empathy, affection, and sociability enhancement empathy, love, and sociability enhancement increased sociability
    Euphoria / Mood Elevation ×2
    10
    physical euphoria cognitive euphoria euphoria mood lift
    Stimulation ×1
    10
    stimulation wakefulness teeth grinding increased heart rate
    Sensory Enhancement ×1
    10
    tactile enhancement color enhancement increased libido
    Stimulant 8.8
    Intense+ 9/10

    Strong stimulation, euphoria, focus, and anxiety/jitters

    Stimulation / Energy ×3
    10
    stimulation wakefulness
    Euphoria / Mood Lift ×2
    10
    physical euphoria cognitive euphoria euphoria mood lift motivation enhancement
    Focus / Productivity ×2
    10
    focus enhancement analysis enhancement motivation enhancement thought acceleration
    ⚠ Anxiety / Jitters ×1
    10
    anxiety teeth grinding increased heart rate bruxism sweating
    Based on reports from:
    Erowid Experience Reports PsychonautWiki 4-FA The Drug Users Bible 4-FA
    View methodology →

    Tolerance

    Build-up develops over days to weeks of regular use
    Reset 3–7 days for acute; 1–3 weeks for full reset

    Tolerance Decay

    Full tolerance 2d Half tolerance 7d Baseline ~14d

    Anecdotal: tolerance builds quickly with repeated/weekly use and decays over 2–4+ weeks; cross-tolerance likely overlaps with other amphetamine-like stimulants and serotonergic releasers. Data quality is limited.

    Cross-Tolerances

    amphetamine
    50%
    methamphetamine
    40%
    MDMA
    30%

    Effects Erowid Bluelight

    Aggregated from 57 Erowid and 18 Bluelight experience reports

    Positive Effects 29

    Stimulation 76.0% 89%
    Euphoria 72.0% 92%
    Sociability Enhancement 66.7% 86%
    Empathy 42.7% 82%
    Music Enhancement 41.3% 90%
    Focus Enhancement 37.3% 84%
    Tactile Enhancement 30.7% 85%
    Body High 18.7% 82%
    Color Enhancement 17.3% 82%
    Thought Acceleration 16.7% 83%
    Happiness 16.7% 90%
    Joy 11.1% 90%
    Mood Elevation 11.1% 82%
    Confidence 11.1% 88%
    Libido Enhancement 11.1% 78%
    Introspection 10.7% 75%
    Creativity Enhancement 6.7% 85%
    Lightness 5.6% 85%
    Buzzing 5.6% 85%
    Thought Connectivity 5.6% 70%

    Adverse Effects 32

    Body Load 38.9% 74%
    Anxiety 38.7% 72%
    Increased Heart Rate 35.1% 70%
    Pupil Dilation 29.8% 70%
    Insomnia 27.8% 85%
    Nausea 24.6% 70%
    Visual Distortions 22.7% 68%
    Muscle Tension 19.3% 70%
    Headache 14.6% 75%
    Confusion 13.3% 85%
    Paranoia 11.1% 82%
    Tremor 11.1% 78%
    Delusion 11.1% 80%
    Hot Flashes 11.1% 80%
    Dry Mouth 11.1% 80%
    Sweating 10.7% 85%
    Memory Suppression 10.5% 70%
    Disrupted Sleep Architecture 5.6% 80%
    Distractibility 5.6% 75%
    Focus Suppression 5.6% 75%

    Combinations TripSit

    4-FA's nerd page Pharmacology, chemical data, effect profiles, and more
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    Helpful Links

    📘 Experience Reports 📖 TheDrug.Wiki 📖 PsychonautWiki 📖 TripSit 📖 The Drug Users Bible