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Summary sheet: 4F-MPH
Chemical Nomenclature
Common names 4F-MPH, 4-FMPH
Substitutive name 4-Fluoromethylphenidate
Systematic name Methyl 2-(4-fluorophenyl)-2-(piperidin-2-yl)acetate
Class Membership
Psychoactive class Stimulant
Chemical class Phenidate
Routes of Administration

WARNING: Always start with lower doses due to differences between individual body weight, tolerance, metabolism, and personal sensitivity. See responsible use section.

Threshold < 5 mg
Light 5 - 10 mg
Common 10 - 15 mg
Strong 15 - 20 mg
Heavy 20 mg +
Total 4 - 8 hours
Onset 30 - 60 minutes
Peak 2 - 4 hours
Offset 1 - 2 hours
After effects 5 - 10 hours

Threshold 5 mg
Light 5 - 8 mg
Common 8 - 14 mg
Strong 14 - 20 mg
Heavy 20 mg +
Total 3 - 6 hours
Onset 10 - 30 minutes
Peak 1 - 2 hours
Offset 1 - 2 hours
After effects 4 - 8 hours

DISCLAIMER: PW's dosage information is gathered from users and resources for educational purposes only. It is not a recommendation and should be verified with other sources for accuracy.


4-Fluoromethylphenidate (commonly known as 4F-MPH) is a novel synthetic stimulant of the phenidate class that produces long-lasting euphoriant, and stimulating effects when administered. It is a closely related structural analog of the commonly prescribed ADHD drug methylphenidate (known by the brand-names Ritalin and Concerta).

The two substances are believed to have very similar pharmacological mechanisms as monoamine reuptake inhibitors but have been reported to display distinctive subjective effects, with 4F-MPH being considered significantly more euphoric and recreational. Anecdotal reports suggest that it is considerably more potent with fewer uncomfortable side effects such as anxiety, muscle spasms and compulsive redosing.[1] This perhaps owes to the fact that it has been shown to act as a higher efficiency dopamine reuptake inhibitor than the parent compound methylphenidate.[2][3][4][5][6]

4F-MPH has an extremely short history of recreational use. It was initially developed as a replacement for ethylphenidate which became illegal in the United Kingdom on April 2015 following a temporary blanket ban. Shortly after, it became available for sale on the online gray market as a research chemical for global distribution.

Due to its potent, long-lasting stimulant effect, likely habit-forming properties as well as unknown toxicity profile, it is strongly recommended that one use proper harm reduction practices if choosing to use this substance.


4F-MPH is a synthetic molecule of the substituted phenethylamine and substituted phenidate classes, and a fluorinated analog of methylphenidate. It contains a phenethylamine core featuring a phenyl ring bound to an amino -NH2 group through an ethyl chain. It is structurally similar to amphetamine, featuring a substitution at Rα which is incorporated into a piperidine ring ending at the terminal amine of the phenethylamine chain. Additionally, it contains a methyl acetate bound to Rβ or its structure. 4F-MPH is structurally identical to methylphenidate with the exception of a single fluorine atom bound to the four position on the phenethylamine core.

With respect to nomenclature, the methyl- in methylphenidate regards the side chain of one carbon atom, while phen- indicates the phenyl ring. Id- is contracted from a piperidine ring, and -ate indicates the acetate group containing the oxygen atoms. Like its parent molecule, 4F-MPH is a chiral compound, presumably produced as a racemic mixture.

Of note is the scientific finding that amphetamine analogs containing fluorine, chlorine, bromine and methyl groups are typically stronger than those without.[citation needed]



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As such, it may contain incomplete or wrong information. You can help by expanding it.

4F-MPH is thought to act primarily as a dopamine and norepinephrine reuptake inhibitor, meaning it effectively boosts the levels of dopamine and norepinephrine neurotransmitters in the brain by binding to and partially blocking the transporter proteins that normally clear these catecholamines from the synaptic cleft. This allows dopamine and norepinephrine to accumulate within the reward pathways in the brain, resulting in stimulating and euphoric effects.

According to a pharmacological evaluation, the (±)-threo isomer of 4F-MPH is 2.15 times more effective at dopamine reuptake inhibition, and 2.7 times more at norepinephrine reuptake inhibition, than its parent compound methylphenidate. The (±)-erythro isomer, however, is 65 times less effective at dopamine reuptake inhibition and 45.6 times less effective at norepinephrine reuptake inhibition than methylphenidate. Neither racemate of 4F-MPH has a significant impact on serotonin reuptake.[7]

Subjective effects

Disclaimer: The effects listed below cite the Subjective Effect Index (SEI), an open research literature based on anecdotal user reports and the personal analyses of PsychonautWiki contributors. As a result, they should be viewed with a healthy degree of skepticism.

It is also worth noting that these effects will not necessarily occur in a predictable or reliable manner, although higher doses are more liable to induce the full spectrum of effects. Likewise, adverse effects become increasingly likely with higher doses and may include addiction, severe injury, or death ☠.

Physical effects

After effects
Aftereffects (3).svg

Cognitive effects

Experience reports

There are currently no anecdotal reports which describe the effects of this compound within our experience index. Additional experience reports can be found here:

Toxicity and harm potential


This toxicity and harm potential section is a stub.

As a result, it may contain incomplete or even dangerously wrong information! You can help by expanding upon or correcting it.
Note: Always conduct independent research and use harm reduction practices if using this substance.

The toxicity and long-term health effects of recreational 4F-MPH use do not seem to have been studied in any scientific context and the exact toxic dosage is unknown. This is because 4F-MPH is a research chemical with very little history of human usage. Anecdotal evidence from people who have tried 4F-MPH suggests that there are no negative health effects attributed to simply trying the drug by itself at low to moderate doses and using it very sparingly (but nothing can be completely guaranteed). Independent researchshould always be done to ensure that a combination of two or more substances is safe before consumption.

It is strongly recommended that one use harm reduction practices when using this drug.

Tolerance and addiction potential

In terms of its tolerance, 4F-MPH can be used multiple days in a row for extended periods of time, but acute tolerance does exist and builds up gradually over repeated extended use. This results in the user requiring an increase in dosage to achieve the same effects. Tolerance is reported to build quicker than methylphenidate.

4F-MPH has potential for abuse on par with that of amphetamine or MDMA due to its lack of significant tolerance, euphoric effects and action upon dopamine transporters.

Dangerous interactions

Warning: Many psychoactive substances that are reasonably safe to use on their own can suddenly become dangerous and even life-threatening when combined with certain other substances. The following list provides some known dangerous interactions (although it is not guaranteed to include all of them).

Always conduct independent research (e.g. Google, DuckDuckGo, PubMed) to ensure that a combination of two or more substances is safe to consume. Some of the listed interactions have been sourced from TripSit.

  • 25x-NBOMe & 25x-NBOH - 25x compounds are highly stimulating and physically straining. Combinations with 4F-MPH should be strictly avoided due to the risk of excessive stimulation and heart strain. This can result in increased blood pressure, vasoconstriction, panic attacks, thought loops, seizures, and heart failure in extreme cases.
  • Alcohol - Combining alcohol with stimulants can be dangerous due to the risk of accidental over-intoxication. Stimulants mask alcohol's depressant effects, which is what most people use to assess their degree of intoxication. Once the stimulant wears off, the depressant effects will be left unopposed, which can result in blackouts and severe respiratory depression. If mixing, the user should strictly limit themselves to only drinking a certain amount of alcohol per hour.
  • DXM - Combinations with DXM should be avoided due to its inhibiting effects on serotonin and norepinephrine reuptake. There is an increased risk of panic attacks and hypertensive crisis, or serotonin syndrome with serotonin releasers (MDMA, methylone, mephedrone, etc.). Monitor blood pressure carefully and avoid strenuous physical activity.
  • MDMA - Any neurotoxic effects of MDMA are likely to be increased when other stimulants are present. There is also a risk of excessive blood pressure and heart strain (cardiotoxicity).
  • MXE - Some reports suggest combinations with MXE may dangerously increase blood pressure and increase the risk of mania and psychosis.
  • Dissociatives - Both classes carry a risk of delusions, mania and psychosis, and these risk may be multiplied when combined.
  • Stimulants - 4F-MPH may be dangerous to combine with other stimulants like cocaine as they can increase one's heart rate and blood pressure to dangerous levels.
  • Tramadol - Tramadol is known to lower the seizure threshold[8] and combinations with stimulants may further increase this risk.

Legal status


This legality section is a stub.

As such, it may contain incomplete or wrong information. You can help by expanding it.

  • Germany: 4-Fluoromethylphenidate was controlled under the NpSG (New Psychoactive Substances Act)[10] as of November 26, 2016.[11], but has been accidentally legalized in September 2022. It is considered to be legal again.
  • Italy: 4F-MPH is a schedule I substance and is illegal to possess, produce, sell and buy.
  • Switzerland: 4F-MPH is a controlled substance specifically named under Verzeichnis E.[12]
  • Turkey: 4F-MPH is a classed as drug and is illegal to possess, produce, supply, or import.[13]
  • United Kingdom: 4-Fluoromethylphenidate is a class B drug in the UK as of 31st May 2017 and is illegal to possess, produce or supply. [14]
  • United States: 4-Fluromethylphenidate is a Schedule I controlled substance in the state of Alabama.[15]

See also

External links


  1. http://www.bluelight.org/vb/threads/770658-4-Fluoromethylphenidate-(4F-MPH)
  2. Deutsch, H. M., Shi, Q., Gruszecka-Kowalik, E., Schweri, M. M. (15 March 1996). "Synthesis and Pharmacology of Potential Cocaine Antagonists. 2. Structure−Activity Relationship Studies of Aromatic Ring-Substituted Methylphenidate Analogs". Journal of Medicinal Chemistry. 39 (6): 1201–1209. doi:10.1021/jm950697c. ISSN 0022-2623. 
  3. Schweri, M. M., Deutsch, H. M., Massey, A. T., Holtzman, S. G. (May 2002). "Biochemical and behavioral characterization of novel methylphenidate analogs". The Journal of Pharmacology and Experimental Therapeutics. 301 (2): 527–535. doi:10.1124/jpet.301.2.527. ISSN 0022-3565. 
  4. Davies, H. M. L., Hopper, D. W., Hansen, T., Liu, Q., Childers, S. R. (5 April 2004). "Synthesis of methylphenidate analogues and their binding affinities at dopamine and serotonin transport sites". Bioorganic & Medicinal Chemistry Letters. 14 (7): 1799–1802. doi:10.1016/j.bmcl.2003.12.097. ISSN 0960-894X. 
  5. Misra, M., Shi, Q., Ye, X., Gruszecka-Kowalik, E., Bu, W., Liu, Z., Schweri, M. M., Deutsch, H. M., Venanzi, C. A. (15 October 2010). "Quantitative structure-activity relationship studies of threo-methylphenidate analogs". Bioorganic & Medicinal Chemistry. 18 (20): 7221–7238. doi:10.1016/j.bmc.2010.08.034. ISSN 1464-3391. 
  6. Singh, S. (1 March 2000). "Chemistry, Design, and Structure−Activity Relationship of Cocaine Antagonists". Chemical Reviews. 100 (3): 925–1024. doi:10.1021/cr9700538. ISSN 0009-2665. 
  7. McLaughlin, G., Morris, N., Kavanagh, P. V., Power, J. D., Dowling, G., Twamley, B., O’Brien, J., Hessman, G., Murphy, B., Walther, D., Partilla, J. S., Baumann, M. H., Brandt, S. D. (March 2017). "Analytical characterization and pharmacological evaluation of the new psychoactive substance 4-fluoromethylphenidate (4F-MPH) and differentiation between the (±)- threo and (±)- erythro diastereomers: Analytical characterization and pharmacological evaluation of 4-fluoromethylphenidate". Drug Testing and Analysis. 9 (3): 347–357. doi:10.1002/dta.2167. ISSN 1942-7603. 
  8. Talaie, H.; Panahandeh, R.; Fayaznouri, M. R.; Asadi, Z.; Abdollahi, M. (2009). "Dose-independent occurrence of seizure with tramadol". Journal of Medical Toxicology. 5 (2): 63–67. doi:10.1007/BF03161089. eISSN 1937-6995. ISSN 1556-9039. OCLC 163567183. 
  9. Gillman, P. K. (2005). "Monoamine oxidase inhibitors, opioid analgesics and serotonin toxicity". British Journal of Anaesthesia. 95 (4): 434–441. doi:10.1093/bja/aei210Freely accessible. eISSN 1471-6771. ISSN 0007-0912. OCLC 01537271. PMID 16051647. 
  10. "Anlage NpSG" (in German). Bundesministerium der Justiz und für Verbraucherschutz. Retrieved December 23, 2019. 
  11. "Gesetz zur Bekämpfung der Verbreitung neuer psychoaktiver Stoffe" (PDF) (in German). Bundesanzeiger Verlag. Retrieved December 23, 2019. 
  12. "Verordnung des EDI über die Verzeichnisse der Betäubungsmittel, psychotropen Stoffe, Vorläuferstoffe und Hilfschemikalien" (in German). Bundeskanzlei [Federal Chancellery of Switzerland]. Retrieved January 1, 2020. 
  13. Cumhurbaşkanı Kararı Karar Sayısı : 1335 | https://resmigazete.gov.tr/eskiler/2019/07/20190720-19.pdf
  14. The Misuse of Drugs Act 1971 (Amendment) Order 2017 
  15. Alabama SB333, 2014, Regular Session