4-FA is a synthetic substituted amphetamine that produces a distinctive combination of stimulant and entactogenic effects. It became commercially available as a research chemical in the early 2000s and gained particular popularity in the Netherlands. Users commonly describe its effects as intermediate between amphetamine and MDMA, with a moderate entactogenic onset that gradually transitions into traditional amphetamine-type stimulation. Very little data exists regarding its pharmacological properties, metabolism, and toxicity.
Also known as: Pfa, Rdj, Flux, 4-fmp, Pal-303, Para-fluoroamphetamine, P-fluoroamphetamine, 4-Fluoroamphetamine, 4-Fluoroamphetamin
Classification
Chemical: Amphetamine
Chemical: Phenethylamine
Psychoactive: Entactogen
Psychoactive: Psychedelic
Psychoactive: Stimulant
Tag: Common
Tag: Empathogen
Tag: Habit-Forming
Tag: Research-Chemical
Tag: Substituted amphetamine
Effects
Stimulation
Physical Euphoria
Increased Heart Rate
Increased Perspiration
Increased Energyalertness
Decreased Need For Sleep
Euphoria
Empathy Love And Sociability Enhancement
Thought Acceleration
Thought Connectivity
Focus Enhancement
Ego Inflation
Sexual Arousal
Tactile Enhancement
Dehydration
Appetite Suppression
Increased Sexuality
Visual And Auditory Hallucinations
Routes of Administration
Oral
Dosage
Heavy: 115-150 mg
Light: 40 – 100 mg
Common: 100 – 130 mg
Strong: 130 – 150 mg
Threshold: 10–15 mg
Duration
Onset: 0.33-0.67 h
Comeup: 0.5-1.25 h
Peak: 2.5-3.5 h
Offset: 2-3 h
After Effects: 6-12 h
Total Duration: 5-8 h
Insufflated
Dosage
Heavy: 60 mg+
Light: 5–15 mg
Common: 15–30 mg
Strong: 30–60 mg
Threshold: 5 mg
Duration
Onset: 0.08-0.17 h
Peak: 0.5-1.5 h
Offset: 1.5-3 h
After Effects: 2-8 h
Total Duration: 3-5 h
Harm Reduction
Check interactions before mixing substances, pay attention to dose spacing and hydration, and treat all dosage guidance as approximate rather than guaranteed safe.
Sources
Substance data is aggregated from the following public harm-reduction and reference sources.
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4-FA - Guide des substances DrugsPRO
4-FA: 4-FA is a synthetic substituted amphetamine that produces a distinctive combination of stimulant and entactogenic effects. It became commercially available as a research chemical in the early 2000s and gained particular popularity in the Netherlands. Users commonly describe its effects as inte
