DOSEGUY

Flmodafinil

guinea pig

Also seen as: CRL-40,940, Bisfluoromodafinil

The Dose Guy’s verdict
Sep 1, 2026
1 source

Flmodafinil is sold as a more potent, better-absorbed version of modafinil. It might be, but nobody has tested the claim. The one human study dosed a few volunteers at 20 mg for drug-test analysis, not wakefulness, and that’s the entire evidence base. No efficacy trial, no safety data, no dose comparison. If you’re picking a wakefulness tool, modafinil has the receipts, and adrafinil offers the same mechanism at the cost of liver conversion.

Would I take it?Probably not. Modafinil with the evidence stripped out.

What it is

Flmodafinil is a bisfluoro structural analog of modafinil, meaning two fluorine atoms replace two hydrogens on the diphenyl rings. The fluorination is why vendors claim higher potency and better oral absorption, and structurally the reasoning isn’t baseless, but it has never been tested in a study that measured wakefulness, cognition, or any outcome a person would care about. Fladrafinil is the prodrug form: your body converts fladrafinil into flmodafinil, so both compounds end up at the same place. The whole modafinil-analog family, flmodafinil, fladrafinil, hydrafinil myristate, lives in a gap between a proven drug and research chemicals sold on its reputation.

What the research shows

No human trials. Zero. Everything below is animal or in-vitro work. Read it as “interesting,” not “evidence it works in you.”

The human data is a single anti-doping study. Everything else is structural speculation:

In a study where six volunteers each ingested 20 mg of either flmodafinil or fladrafinil, flmodafinil acid and flmodafinil sulfone were detected as metabolites. Maximum blood concentrations ranged from 45 to 98 ng/mL, and maximum urinary concentrations from 191 to 891 ng/mL.Drug Test Anal 2026 · PK
No randomized or controlled human trial of flmodafinil for wakefulness, cognition, or any clinical outcome exists.as of Aug 2026
No human study reporting adverse events or clinical safety outcomes after flmodafinil use exists.as of Aug 2026

Realistic protocols

No studied human dose exists. The community runs flmodafinil at 50 to 200 mg orally, with most people landing around 100 mg for a work day. The logic is that it’s stronger than modafinil so you need less, but without a dose-comparison study no dose-comparison study supports that claim. If you’re reaching for this instead of modafinil, be honest about why: availability, not evidence. Keep the dose conservative, take it early in the day, and don’t combine it with other stimulants or modafinil-family compounds. The only studied human dose is 20 mg for drug-testing purposes, which tells you nothing about what works for wakefulness. Flmodafinil is a WADA class S6 prohibited stimulant. If you compete in tested sport, it will flag.

Side effects

Zero clinical safety data. Community anecdote, mapped onto what modafinil’s track record suggests:

anecdotalHeadache, appetite suppression, and jitteriness, the standard stimulant cluster.
anecdotalInsomnia when dosed late. Standard for the wakefulness class.
anecdotalOccasional anxiety or overstimulation, more common at higher doses and in people sensitive to modafinil.
unknownZero clinical safety data. The modafinil safety record does not transfer to its analogs automatically. A different molecule is a different risk profile until someone studies it.

Where to buy

No live listings from tracked vendors right now.