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Hyd2.5
Hydrafinil (Fluorenol) Research
Mostly mechanism / observational
5 peer-reviewed studies
What the evidence says
Mostly mechanism / observational
Most Hydrafinil (Fluorenol) studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from mixed-quality randomised trials published 1997–2026.
Based on 5 studies · 2 RCTs
Confidence
Low confidence
By outcome
Safety profile
Mostly mechanism / observational5 studies
Focus & attention (modafinil-class, unproven for hydrafinil)Focus/attention is extrapolated from modafinil and unproven for hydrafinil; insomnia, anxiety, raised BP/HR and grey-market identity risk. · Not established (no human data)
Mostly mechanism / observational4 studies
Wakefulness & fatigueVendor-claimed wakefulness/alertness in the eugeroic class; essentially unstudied, with no human efficacy data and uncharacterised pharmacology. · Not established (no human data)
Mostly mechanism / observational3 studies
Cognition (modafinil-class evidence)
Too few graded studies2 studies
Sleep disruption / insomnia
Too few graded studies1 study
Wakefulness timing & vigilance
Too few graded studies1 study
Active research area
2 studies in the last 5 years
199720112026
1Crossover1997
In plain English: Compared with placebo, modafinil 200 and 400 mg significantly increased the mean sleep latency on the Maintenance of Wakefulness Test by 40% and 54% ... As little as a 200-mg daily dose of modafinil is therefore an effective and well-tolerated treatment.
Broughton RJ, Fleming JA, George CF, Hill JD, Kryger MH, Moldofsky H, Montplaisir JY, Morehouse RL, Moscovitch A, Murphy WF. · Neurology (1997)
MODAFINIL (a DIFFERENT drug), NOT HYDRAFINIL: a randomized, double-blind, placebo-controlled crossover trial of modafinil for excessive daytime sleepiness in narcolepsy — real human evidence for the modafinil-class drug
Modafinil reduced objective and subjective daytime sleepiness vs placebo and was generally well tolerated in this supervised clinical population
Establishes the modafinil-class wakefulness effect in humans — but for modafinil, NOT for the essentially unstudied hydrafinil
In plain English: Modafinil may well deserve the title of the first well-validated pharmaceutical nootropic agent ... modafinil appears to consistently engender enhancement of attention, executive functions, and learning. Importantly, we did not observe any preponderances for side effects or mood changes.
Battleday RM, Brem AK. · European Neuropsychopharmacology (2015)
MODAFINIL (a DIFFERENT drug), NOT HYDRAFINIL: a systematic review of modafinil for cognitive neuroenhancement in healthy non-sleep-deprived adults — included only to show what the modafinil-class drug does, not what hydrafinil does
Found modest, task-dependent benefits to attention, executive function and learning with modafinil, especially on more complex tasks
Gestured at by hydrafinil vendors as if it were hydrafinil evidence — it is NOT; hydrafinil is a distinct fluorene alcohol with no human cognition trials and no established structural equivalence
In plain English: Modafinil significantly improved the ability to stay awake compared with placebo ... The most common adverse events were headache, nausea, and nervousness. Modafinil was well tolerated and was not associated with any serious adverse events.
US Modafinil in Narcolepsy Multicenter Study Group. · Neurology (2000)
MODAFINIL (a DIFFERENT drug), NOT HYDRAFINIL: a large multicenter randomized placebo-controlled trial of modafinil for excessive daytime somnolence in narcolepsy — modafinil-class human evidence
Modafinil improved objective wakefulness vs placebo; the most common adverse events were headache, nausea and nervousness — the same symptoms extrapolated to hydrafinil
Reinforces the modafinil-class effect AND its typical adverse-event profile in supervised humans, for the modafinil-class drug only
In plain English: Little information on the human metabolism and urinary elimination of hydrafinil (9-fluorenol) exists. In order to support preventive anti-doping activities concerning compounds such as hydrafinil, a pilot elimination study was conducted with three healthy male volunteers receiving a single oral dose of 50 mg of hydrafinil.
Knoop A, Fußhöller G, Haenelt N, Goergens C, Guddat S, Geyer H, Thevis M. · Drug Testing and Analysis (2021)
HYDRAFINIL-SPECIFIC (the only direct human study): a doping-control pilot in which three healthy male volunteers each took a single 50 mg oral dose of hydrafinil (9-fluorenol), characterizing how it and its phase I/II metabolites are excreted in urine and detected
Explicitly states that 'little information on the human metabolism and urinary elimination of hydrafinil exists' — documenting the near-total absence of human pharmacology, not any clinical benefit
Identified intact hydrafinil plus primarily hydroxylated and glucuronidated/sulfo-conjugated metabolites — human pharmacokinetic/metabolite data, relevant to detection windows
In plain English: We have disclosed the 9-fluorenol-catalyzed reductive dehalogenation of aryl halides. 9-Fluorenol, a readily available and structurally simple organic compound, serves as a catalytic single-electron reductant under light- and electricity-free conditions.
Koike S, Kashihara M, Nakao Y. · Chemistry, an Asian Journal (2026)
NOT a nootropic study: this is synthetic organic chemistry in which 9-fluorenol (the chemical sold as hydrafinil) is used as a catalytic single-electron reductant to dehalogenate aryl halides
Included to illustrate what the genuine peer-reviewed literature on 9-fluorenol actually consists of — analytical and synthetic chemistry of the molecule, NOT human or animal nootropic pharmacology
Confirms 9-fluorenol is a simple, readily-available organic compound; it says nothing about cognition, wakefulness, efficacy or safety in any organism