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4-Fluoromethcathinone (4-FMC)
by Erowid
Caution :   Reactions and experiences may vary dramatically from person to person. [see below]
4-Fluoromethcathinone Duration
( tentative )
Total Duration
1.5 - 4 hrs
15 - 45 mins
Coming Up
15 - 30 mins
30 - 60 mins
Coming Down
30 - 90 mins
After Effects
2 - 4 hrs
Hangover / Day After
- - -
4-Fluoromethcathinone Duration
( tentative )
Total Duration
1 - 2.5 hrs
2 - 5 mins
Coming Up
5 - 10 mins
10 - 60 mins
Coming Down
45 - 90 mins
After Effects
2 - 4 hrs
Hangover / Day After
- - -
  • mental and physical stimulation
  • euphoria, mood lift
  • feelings of empathy, openness
  • increase in sociability, desire to talk with others
  • pleasurable rushing
  • increased concentration
  • increased sense of motivation
  • general change in consciousness (as with most psychoactives)
  • decreased appetite
  • pupil dilation
  • unusual body sensations (facial flushing, chills, goosebumps, body energy)
  • change in body temperature regulation
  • sweating
  • increase in heart rate and blood pressure
  • nystagmus
  • tremor
    (likelihood of negative side effects increases with higher doses)
  • desire to redose, craving to recapture initial euphoric rush
  • uncomfortable changes in body temperature (sweating/chills)
  • heart palpitations
  • significant increase in heart rate and blood pressure
  • impaired short term memory
  • tightened jaw muscles, grinding teeth (trismus and bruxia)
  • muscle twitching, stiffness, tension, pain
  • nystagmus
  • dizziness, light headedness, vertigo
  • headache
  • nausea
  • numbness/tingling in extremities
  • when insufflated: pain and swelling in nose and throat, sinusitis, nasal bleeding
General Effects Notes
The effects of 4-fluoromethcathinone are often compared to those of 4-methylmethcathinone (mephedrone), but with significantly less euphoria or feelings of empathy reported. Some users have noted that it feels "toxic", with lingering side effects such as headache, muscle tension and nausea.

Confusingly, both 4-FMC and, less frequently, its positional isomer 3-FMC have been referred to as "Flephedrone"; they seem to have similar effects.

Routes of Administration
As with other psychoactives, oral 4-fluoromethcathinone ingestion takes slightly longer to cause effects and lasts longer. Insufflation (snorting) is more associated with compulsive / addictive use patterns.

Addiction and Compulsive Use
As with 4-methylmethcathinone, compulsive use patterns that are similar to or stronger than those of other recreational euphoric stimulants have been reported. It is unlikely to be physically addictive, meaning that withdrawal symptoms are minimal and likely not life threatening, but psychological addiction seems likely to be a problem in some users with this substance.

"[unspecified dose and ROA] While 4-fluoromethcathinone is reasonably useful as a stimulant at various dosages, there are well-studied pharmaceuticals that perform much better. 4-FMC always left me with a sort of "'so what?' feeling and no urge whatsoever to take my experiments further." -- "Study of Four Cathinones", Erowid Extracts Jun 2012;(22)10.
"[30-50 mg, insufflated / 100-200 mg, oral] 4-FMC turned out to be a valuable tool for increasing energy, motivation, and, to some degree, concentration. [...] For general stimulation, insufflated doses of 3050 mg and oral doses of 100200 mg seemed to work best." -- "Study of Four Cathinones", Erowid Extracts Jun 2012;(22)11.
"[150 mg, rectal] Still working on my music collection. It seems a bit like amphetamine in that it encourages mindless repetitive activity. In small doses it could be used as a study aid, perhaps. It is much less more a plain stimulant than mephedrone, methylone, bk-MBDB, less empathic. It is has a low quotient (but not zero) of entactogenic qualities. I feel no uncomfortably elevated heart rate or other signs of physical discomfort so I decide the dose may be too low." -- Exp 86047
"[repeated, oral, total ~400 mg] [...] pain and feelings of numbness in all extremities, intense tingling sensations and extreme sensitivity to touch, where even slight contact causes intense pain. Dizzyness, even feeling faintish periodically. Hand & feet freezing cold. Intermittent attacks of nausia. Unusually intense bodily (muscular) stiffness. Headache." -- Exp 84061
Erowid's effects information is a summary of data gathered from users, research, and other resources. This information is intended to describe the range of effects people report experiencing. Effects may vary dramatically from one person to another or one experience to another based on a variety of factors such as body chemistry, age, gender, physical health, dose, form of material, etc.