I wanted to write this experience report because I have never seen any documentation of addiction to research chemical (halogenated) amphetamines. Not a single forum post or report that someone was hooked on this dirty halogenated amphetamine class like I was. So I figured I'd tell my story.
4-FMA
Well-documented
Well-documented
Multiple authoritative sources agree on dosing and effects.
- 3 corroborating sources
- 1 ROA with full dose ladder
- duration data present
- 20 combo interactions documented
- PubChem toxicity data
- classified Research-chemical
Well-documented
Multiple authoritative sources agree on dosing and effects.
- 3 corroborating sources
- 1 ROA with full dose ladder
- duration data present
- 20 combo interactions documented
- PubChem toxicity data
- classified Research-chemical
Aliases: 4-fluromethamphetamine, 4fma
Summary
4-Fluoromethamphetamine (also known as 4-FMA) is a lesser-known novel stimulant-entactogen substance of the amphetamine class. 4-FMA is chemically related to 4-FA and methamphetamine. Little is known about its pharmacology, but it likely produces its effects by increasing levels of dopamine, norepinephrine, and serotonin in the brain.
Dose Information
| ROA | Light | Common | Strong | Heavy |
|---|---|---|---|---|
| Oral | 25-50mg | 50-75mg | 100-125mg | 125mg+ |
Light
Common
Strong
Heavy
Onset, Duration & After-effects
| ROA | Onset | Comeup | Peak | Offset | Total |
|---|---|---|---|---|---|
| Oral | 18-42 min | 18-42 min | 2-5 hrs | 1-2 hrs | 3-5 hrs |
Effect Profile
2 reportsScores (1–10) curated from multiple sources:
- Effect keyword matching from PsychonautWiki catalog
- Weighted by importance: core (×3), major (×2), minor (×1)
Psychedelic
0.6
Threshold
1/10
Strong body load with low headspace
Visual Intensity
×3
0
Headspace Depth
×3
1
time distortion
Auditory Effects
×1
0
Body Load / Somatic Effects
×1
8
vasoconstriction
bruxism
teeth grinding
sweating
increased heart rate
Empathogen
6.1
Strong
6/10
Strong euphoria with moderate stimulation, mild empathy, low sensory enhancement
Empathy / Social Openness
×3
5
empathy, affection and sociability enhancement
increased sociability
Euphoria / Mood Elevation
×2
10
physical euphoria
euphoria
cognitive euphoria
mood lift
Stimulation
×1
7
stimulation
wakefulness
teeth grinding
increased heart rate
Sensory Enhancement
×1
1
increased libido
Stimulant
5.9
Strong
6/10
Strong euphoria and anxiety/jitters with moderate focus, mild stimulation
Stimulation / Energy
×3
5
stimulation
wakefulness
Euphoria / Mood Lift
×2
10
physical euphoria
euphoria
cognitive euphoria
mood lift
motivation enhancement
Focus / Productivity
×2
6
analysis enhancement
motivation enhancement
thought acceleration
Anxiety / Jitters
×1
10
anxiety
paranoia
bruxism
increased heart rate
teeth grinding
vasoconstriction
+1 more
Based on reports from:
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
1d
Half tolerance
12d
Baseline
~21d
Acute tolerance: develops within a single session — the reset numbers above apply after sustained heavy use, not after one binge. Within-session tachyphylaxis usually resets largely overnight.
Cross-Tolerances
Stimulants
Amphetamine
75%
Methamphetamine
75%
Lisdexamfetamine
75%
2-FA
75%
2-FMA
75%
3-FA
75%
Methylphenidate
75%
Empathogens
4-FA
40%
Effects
Positive
- Increased energy/alertness
- Physical euphoria
- Bronchodilation
- Stimulation
Negative
- Weight loss
- Sweating
- Bruxism
- Headache
- Vasoconstriction
- Temporary erectile dysfunction
- Pupil dilation
- Increased heart rate
- Increased perspiration
- Abnormal heartbeat
- Teeth grinding
- Tremor
- Decreased need for sleep
- Decreased appetite
- Disturbed sleep patterns
- Itchiness
- Restless legs
- Muscle contractions
- Increased bodily temperature
- Stamina intensification
Positive
- Euphoria
- Increased sociability
- Mood lift
- Empathy, affection and sociability enhancement
- Motivation enhancement
- Novelty enhancement
- Analysis enhancement
- Cognitive euphoria
- Wakefulness
- Immersion intensification
Negative
- Aggressiveness
- Dizziness
- Delusion
- Depression
- Anxiety
- Paranoia
- Irritability
- Thought deceleration
- Depersonalization
- Compulsive redosing
- Cognitive fatigue
- Suicidal ideation
- Psychosis
- Motivation depression
- Excessive talking
- Moodiness
- Thought acceleration
- Ego inflation
- Time distortion
- Focus intensification
Positive
- Increased libido
- Bodily control enhancement
- Increased music appreciation
Negative
- Dehydration
- Disinhibition
- Appetite suppression
- Orgasm depression
- Increased sexuality
- Visual and auditory hallucinations
- Vibrating vision
- Tactile intensification
Combinations
Cross-Check 4-FMA with another substanceCommunity Trip Reports
Anecdotal first-person accounts from Reddit, Erowid, and Bluelight. Click a source to expand. Reports are harm-reduction context, not medical guidance.
Erowid 2 reports 2 neutral visit
Well would only be fair to share some background for reference. now I am 25 used extensively psycho actives, from pharms to rcs to natural to all others. basically its my biggest hobby and has been going strong since day one.
Bluelight 1 thread 1 neutral visit
I have used 4-FMA a lot as it's a higher quality amphetamine and provides a great amphetamine high with a MDMA like buzz to it. I waited until 1pm and I dropped 125mg my ideal dose.
4-FMA's nerd page
Pharmacology, chemical data, effect profiles, and more
→
Helpful Links
Report an issue or suggest an edit
Spotted incorrect or dangerous information, have a correction, a new study, or a useful addition for 4-FMA? Let us know. Reports are reviewed by moderators — this is not posted publicly.