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4-FMA Facts

Stimulant; Substituted amphetamine; Monoamine releasing agent

Description

4-FMA (4-fluoromethamphetamine) is a synthetic stimulant of the substituted amphetamine class. It floods the brain with dopamine, serotonin, and norepinephrine simultaneously,[1] producing a hybrid stimulant-entactogen effect.

Subjective effects include euphoria, empathy enhancement, sociability enhancement, stimulation, and focus enhancement.[2] The experience sits between MDMA's emotional warmth and methamphetamine's driven energy — prosocial openness and physical activation in one state.[1]

Dependence liability is moderate, and the most characterized physical danger is liver toxicity that can strike unpredictably regardless of dose.[3] The liver risk is shaped by genetic variation in drug-metabolizing enzymes — some people produce more toxic breakdown products than others, and alcohol worsens this.[3]

Dose and durationby route · individual sensitivity varies

Oral(mg)
Threshold< 10 mgLight25 – 50 mgCommon50 – 75 mgStrong100 – 125 mgHeavy125+ mg

Starts in 20 – 40 minLasts 4 – 8 hoursAfter-effects 3 – 12 hours

Body and dependence

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

Tolerance

Builds
Moderate
Fully resets after
10.5 days
Carries over to
amphetamine; methamphetamine; cocaine; MDMA; other dopaminergic stimulants

Effectslikely at a common dose

Perception
none likely · 8 possible
Body
Appetite suppression; Dry mouth; Pupil dilation; Stimulation; Wakefulness; +24 possible, including Dehydration sensation, Heart rate perception changes, Insomnia
Thinking
Cognitive euphoria; Thought acceleration; +20 possible, including Compulsive redosing urge, Suggestibility enhancement
Feeling
Euphoria; +9 possible, including Anhedonia, Anxiety, Depression
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
Concurrent MAOI use; Concurrent tramadol use
Relative
Pre-existing cardiovascular or cerebrovascular disease; Pre-existing hypertension; Seizure disorder; Hepatic impairment; CYP2D6 poor metabolizer phenotype; Concurrent CYP2D6 or CYP3A4 inhibitors; Pregnancy; Concurrent serotonergic medications

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-fma
Not graded (3)
Not listed never means safe.

Seek help immediately if

  • Chest pain; racing, pounding, or irregular heartbeat
  • Very high body temperature; heavy sweating; hot, flushed skin
  • Severe agitation, paranoia, panic, or confusion
  • Severe headache; muscle rigidity or twitching
  • Seizures
  • Signs of stroke — face drooping, one-sided weakness, slurred speech
  • Difficulty breathing; collapse or unconsciousness

What to do

  1. Call emergency services for chest pain, overheating, seizure, or unresponsiveness
  2. Move them to a cool, quiet place and reduce stimulation
  3. Cool the body — remove excess clothing, apply cool damp cloths, fan them
  4. Keep them calm; reassure — panic worsens the cardiovascular strain
  5. If seizing, protect from injury (don't restrain); recovery position afterward
  6. Monitor breathing and be ready to give rescue breaths / CPR

Most stimulant overdoses settle with cooling, a calm environment, and time. The medical danger is hyperthermia, cardiac events (arrhythmia, heart attack, stroke), and seizures — get help immediately if any appear.

988 Suicide & Crisis LifelineFireside Project: 62-FIRESIDE

Version r1 · Not medical advice

References

  1. [1]
    ^abRickli 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
  2. [2]
    ^(2024) 4-FMA - PsychonautWiki Link
  3. [3]
    ^abRoque Bravo R, Carmo H, Valente MJ, Silva JP, Carvalho F, Bastos ML, Dias da Silva D (2021) 4-Fluoromethamphetamine (4-FMA) induces in vitro hepatotoxicity mediated by CYP2E1, CYP2D6, and CYP3A4 metabolism — Toxicology doi:10.1016/j.tox.2021.152988
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