Skip to main content
Psychedex
Article

4-FA Facts

Stimulant; Entactogen; Substituted amphetamine; Monoamine releasing agent

Description

4-FA (4-fluoroamphetamine) is a synthetic stimulant and entactogen of the substituted amphetamine class. It floods the brain with dopamine, norepinephrine, and serotonin simultaneously, producing both stimulant drive and emotional warmth.[1][2][3]

Subjective effects include stimulant arousal, emotional warmth, sociability, mood elevation, mild visual distortion, and increased energy.[4] The experience blends amphetamine-like drive with a softer empathogenic glow — more sociable than speed, more clear-headed than MDMA — though the deep emotional attunement of MDMA is absent.[5]

4-FA carries moderate psychological dependence potential and disproportionate cardiovascular toxicity — blood pressure elevation exceeds both MDMA and amphetamine.[6] The greatest danger is cardiovascular: documented outcomes include stress cardiomyopathy, hemorrhagic stroke, and death — and combining it with other serotonergic substances has proven fatal.[7]

Dose and durationby route · individual sensitivity varies

Oral(mg)
Threshold< 25 mgLight25 – 75 mgCommon75 – 130 mgStrong130 – 150 mgHeavy150+ mg

Starts in 45 – 75 minLasts 5 – 8 hoursAfter-effects 6 – 12 hours

Body and dependence

Acute toxicity
High
Chronic toxicity
Moderate
Physical dependence
Low
Psychological dependence
Moderate
Withdrawal
Mild
Compulsive redosing
Moderate

Tolerance

Builds
Moderate
Fully resets after
10 days
Carries over to
amphetamine; methamphetamine; MDMA; methylphenidate

Effectslikely at a common dose

Perception
none likely · 10 possible
Body
Dry mouth; Pupil dilation; Appetite suppression; Stimulation; Insomnia; Wakefulness; +25 possible, including Dehydration sensation, Heart rate perception changes, Vasoconstriction
Thinking
Cognitive euphoria; Thought acceleration; +24 possible, including Cognitive dysphoria, Compulsive redosing urge, Thought disorganization
Feeling
Euphoria; +12 possible, including Anxiety, Depression, Anhedonia
Self
none likely · 9 possible, including Craving, Ego inflation
Time
none likely · 2 possible
Awareness
none likely · 2 possible

Who shouldn't take it

Absolute
Cardiovascular disease; Uncontrolled hypertension; Pregnancy; Concurrent MAOI use
Relative
Psychotic disorders; Concurrent serotonergic drug use; Concurrent antiretroviral therapy (CYP2D6 inhibitors)

Combinations61 recorded

Lethal (2)
MAOIs; Tramadol
Dangerous (33)
Alpha-2 adrenergic receptor antagonist; Anticholinergics; Atypical antipsychotics; Caffeine; Dopamine agonists; Ephedrine, Pseudoephedrine; Local anesthetics; MDMA, Amphetamines; MDMA, MDA; NDRIs (Wellbutrin); NRIs; Opioids; SNRIs; SSRIs; Stimulants; 5-HTP, Tryptophan; Antihistamines; Antipsychotics; Buspirone; Clonidine, Guanfacine; DXM; GHB, Baclofen; GHB, GBL; Ibogaine; and 9 more, see full page
Caution (23)
See full page: psychedex.org/substances/4-fa
Not graded (3)
Not listed never means safe.

Seek help immediately if

  • Overheating / very high body temperature — heavy sweating, then hot dry skin (the leading cause of MDMA deaths, worse when dancing in hot venues)
  • Muscle rigidity, jaw clenching, tremor, or twitching (possible serotonin syndrome)
  • Fast, pounding heartbeat; chest pain
  • Agitation, confusion; seizures
  • Hyponatremia (water intoxication) — headache, confusion, drowsiness, vomiting, and seizures from drinking too much water
  • Nausea/vomiting; collapse or unconsciousness

What to do

  1. Move them somewhere cool and help them cool down — overheating is the main danger
  2. Sip water to stay hydrated but DO NOT overdrink — roughly a cup (250 ml) per hour if active; too much water can be deadly (hyponatremia)
  3. Get them to rest and stop dancing
  4. For overheating, seizures, chest pain, muscle rigidity/tremor, confusion, or unresponsiveness, call emergency services
  5. Recovery position if drowsy or vomiting; stay with them
  6. Be ready to give rescue breaths / CPR

Most resolve with cooling, rest, sensible hydration, and time. The life-threatening dangers are hyperthermia, serotonin syndrome, and hyponatremia (too much water) — each a medical emergency, not something to wait out.

988 Suicide & Crisis LifelineFireside Project: 62-FIRESIDE

Version r1.a1 · Not medical advice

References

  1. [1]
    ^Baumann MH, Clark RD, Woolverton WL, Wee S, Blough BE, Rothman RB (2011) In vivo effects of amphetamine analogs reveal evidence for serotonergic inhibition of mesolimbic dopamine transmission in the rat — Journal of Pharmacology and Experimental Therapeutics doi:10.1124/jpet.110.176271
  2. [2]
    ^Wee S, Anderson KG, Baumann MH, Rothman RB, Blough BE, Woolverton WL (2005) Relationship between the serotonergic activity and reinforcing effects of a series of amphetamine analogs — Journal of Pharmacology and Experimental Therapeutics PMID:15677348
  3. [3]
    ^Rickli A, Hoener MC, Liechti ME (2015) Monoamine transporter and receptor interaction profiles of novel psychoactive substances: para-halogenated amphetamines and pyrovalerone cathinones — European Neuropsychopharmacology doi:10.1016/j.euroneuro.2014.12.012
  4. [4]
    ^Kuypers KPC, De Sousa Fernandes Perna EB, Theunissen EL, Toennes SW, Mason NL, Hutten NRPW, Ramaekers JG (2019) A First-in-Man Study with 4-Fluoroamphetamine Demonstrates it Produces a Mild Psychedelic State — Journal of Psychoactive Drugs doi:10.1080/02791072.2019.1569286
  5. [5]
    ^Dolder PC, de Sousa Fernandes Perna EB, Mason NL, Hutten NRPW, Toennes SW, Theunissen EL, Ramaekers JG, Kuypers KPC (2018) Independent elevation of peripheral oxytocin concentrations and reduction in cognitive empathy during 4-fluoroamphetamine intoxication — Human Psychopharmacology doi:10.1002/hup.2680
  6. [6]
    ^Gresnigt FMJ, Snik A, Franssen EJF, Vanhommerig JW, de Lange DW, Riezebos RK (2022) 4-Fluoroamphetamine (4-FA) intoxication results in exaggerated blood pressure effects compared to MDMA and amphetamine: A retrospective analysis — Journal of the American College of Emergency Physicians Open doi:10.1002/emp2.12813
Print version
Report an issue