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WARNINGDANGER OF DEATH
High doses alone or ordinary doses in combination with other depressants can fatally stop breathing.
Furanylfentanyl
Furanylfentanyl
Fu-F
Furanylfentanyl is a potent synthetic opioid analgesic of the anilinopiperidine class and a structural analogue of fentanyl.citation needed Classified as a research chemical, it has extremely limited pharmacological and toxicological documentation available. It is thought to be somewhat less potent and shorter-acting than butyrfentanyl. Due to the scarcity of reliable information and its high potency, exercising extreme caution with this substance is strongly recommended.
Dosage & Duration
Dosage
Doses are population estimates that vary widely between individuals.
Threshold~200 µg
Light200-400 µg
Moderate400-800 µg
Strong800-1600 µg
Heavy1600+ µg
Duration
Onset1-10 minutes
After Effects1-3 hours
Total1-3 hours
Subjective Effects
Legacy content. A statistically backed ontology from Mindstate Design Labs is coming soon.
The experience is that of a short-acting, extremely potent opioid, dominated by analgesia, sedation, and the characteristic opioid sense of physical and emotional comfort. Its effects closely mirror those of fentanyl itself, though it is roughly half as potent and believed to be somewhat shorter in duration than related analogs such as butyrfentanyl. The margin between an active dose and dangerous respiratory depression is narrow, and sensory alteration beyond bodily sensation is minimal.
Physical
Physical effects follow the fentanyl-analog pattern: pain relief and heavy sedation accompanied by itching and nausea, with potentially life-threatening respiratory depression at higher doses.
Cognitive
The headspace is one of opioid sedation and relief, with little in the way of complex cognitive alteration reported.
Pharmacology
Pharmacodynamics
Furanylfentanyl is an opioid analgesic and a structural analog of fentanyl.23 It exhibits an ED50 of 0.02 mg/kg in mice, and in humans it has been estimated to be 50 to 100 times more potent than morphine, placing it at roughly half the potency of fentanyl.
Pharmacokinetics
The metabolism of Furanylfentanyl has been characterised. Metabolites were formed via N-dealkylation, hydroxylation, amide hydrolysis followed by hydroxylation with glucuronidation or sulfation, dihydrodiol formation followed by hydroxylation or N-dealkylation, oxidative N-dealkylation and reduction of the keto group, and furanyl ring opening and carboxylation.citation needed
Metabolitesnone documented yet
Dangerous
Highest riskThese combinations are considered extremely harmful and should always be avoided. Reactions to these drugs taken in combination are highly unpredictable and have a potential to cause death.
Unsafe
AvoidThere is considerable risk of physical harm when taking these combinations, they should be avoided where possible.
Caution
Use cautionThese combinations are not usually physically harmful, but may produce undesirable effects, such as physical discomfort or overstimulation. Extreme use may cause physical health issues. Synergistic effects may be unpredictable. Care should be taken when choosing to use this combination.
Tolerance
Tolerance timelines are rules of thumb, not exact schedules, and vary widely between individuals and use patterns.
Cross Tolerance
Opioids (full cross-tolerance expected with all μ-opioid receptor agonists)
Harm Potential
Addiction & Dependence
Psychological
HighClassified as habit-forming. As a potent fentanyl analog, it carries significant risk of psychological dependence consistent with other opioids.citation needed
Toxicity
Respiratory
Potentially serious respiratory depression can occur at active doses and is life-threatening; this is the primary mechanism of fatal opioid overdose and represents the most significant acute risk with this substance.citation needed
History & Culture
Furanylfentanyl was first characterized during research conducted in the 1980s, when studies in humans demonstrated it to be approximately 50 to 100 times more potent than morphine, placing it at roughly half the potency of fentanyl.citation needed Despite this early pharmacological…
Legality
International
Furanylfentanyl is included in Schedule I of the 1961 Single Convention on Narcotic Drugs. UNODC records its scheduling year as 2018.
By Country
Illegal6
United StatesIllegal
AustraliaIllegalFuranylfentanyl is expressly listed in Schedule 9 of the current, in-force Poisons Standard. The Federal Register records F2026L00633 as registered and effective on 28 May 2026. Schedule 9 recommends prohibition of manufacture, possession, supply and use except for approved medical or scientific research, analytical, teaching or training purposes. Furanylfentanyl is also listed separately under the Customs (Prohibited Imports) Regulations 1956 for border control.
BrazilIllegalANVISA RDC No. 227 of 17 May 20188
Brazil placed furanilfentanil, the Portuguese name used for furanylfentanyl, on ANVISA's Lista F1 in RDC No. 227 of 17 May 2018. Lista F1 is the list of proscribed substances.
NetherlandsIllegalOpiumwet, lijst I11
Furanylfentanyl staat als zelfstandige vermelding op lijst I bij de Opiumwet. Artikel 2 van de Opiumwet verbiedt onder meer het binnen of buiten Nederland brengen, verkopen, aanwezig hebben en vervaardigen van middelen op lijst I.
SwedenIllegalFörordning (1992:1554) om kontroll av narkotika, bilaga 112
Furanylfentanyl (Fu-F) is expressly listed in the current consolidated Annex 1 to Sweden's narcotics-control ordinance. Substances in that annex are deemed narcotics under the Narcotics Penal Law. The effective date of 25 January 2017 is not established.
UkraineIllegalCabinet of Ministers Resolution No. 770, Table I, List No. 113
Furanylfentanyl (Fu-F; Furanyl fentanyl) is expressly listed in Table I, List No. 1 of the controlled-substances list approved by Cabinet Resolution No. 770. List No. 1 designates especially dangerous narcotic drugs whose circulation is prohibited. The current official text retains the Furanylfentanyl entry and identifies it as N-феніл-N-[1-(2-фенілетил)піперидин-4-іл]фуран-2-карбоксамід.
Controlled / restricted1
References
Source Pages
Citations
- An Expanding World of Novel Psychoactive Substances: Opioids. pmc.ncbi.nlm.nih.gov (n.d.). https://doi.org/10.3389/fpsyt.2017.001101
- In Vitro and In Vivo Pharmacological Characterization of Fentanyl Analogs. (n.d.). https://pmc.ncbi.nlm.nih.gov/articles/PMC12408109/1
- Fentanyl decreases blood oxygen more than furanylfentanyl despite similar effects on breathing. (n.d.). https://pmc.ncbi.nlm.nih.gov/articles/PMC12869654/1
- Anders Helander, Matilda Bäckberg, & Olof Beck. (20 April 2016). Intoxications involving the fentanyl analogs acetylfentanyl, 4-methoxybutyrfentanyl and furanylfentanyl: results from the Swedish STRIDA project. Clinical Toxicology, 54(4), 324–332. https://doi.org/10.3109/15563650.2016.11397151
- Notes from the Field: Furanyl-Fentanyl Overdose Events Caused by Smoking Contaminated Crack Cocaine - British Columbia, Canada, July 15-18, 2016. MMWR. Morbidity and Mortality Weekly Report, 65(37), 1015–1016 (September 2016). https://doi.org/10.15585/mmwr.mm6537a61
- Therapeutic Goods (Poisons Standard—June 2026) Instrument 2026 (F2026L00633), Schedule 9. legislation.gov.au (n.d.). https://www.legislation.gov.au/F2026L00633/latest/text1
- Therapeutic Goods (Poisons Standard—June 2026) Instrument 2026 (F2026L00633), Schedule 9. legislation.gov.au (n.d.). https://www.legislation.gov.au/F2026L00633/latest/details1
- ANVISA RDC No. 227 of 17 May 2018. gov.br (n.d.). https://www.gov.br/anvisa/pt-br/assuntos/medicamentos/controlados/lista-substancias1
- Betäubungsmittelgesetz (BtMG), Anlage II (zu § 1 Abs. 1). gesetze-im-internet.de (n.d.). https://www.gesetze-im-internet.de/btmg_1981/index.html1
- Betäubungsmittelgesetz (BtMG), Anlage II (zu § 1 Abs. 1). gesetze-im-internet.de (n.d.). https://www.gesetze-im-internet.de/btmg_1981/anlage_ii.html1
Further Reading
Calderon SN et al., Respiratory ED50 comparison (PMID 34673011)
CDC HAN alert on fentanyl-laced pills (2016)
CDC MMWR: Furanylfentanyl Crack-Cocaine Overdose Cluster, BC 2016
DEA Final Order: Furanylfentanyl Schedule I (83 FR 61320)
DHS Master Question List: Synthetic Opioids (2024)
DrugWatch Information Sheet: Fentanyls (2017)
EMCDDA Risk Assessment Report: Furanylfentanyl (2017)- Goggin et al.: Furanylfentanyl Metabolites in Urine, J Anal Toxicol (2017)
- Guerrieri et al.: Postmortem Findings in Furanylfentanyl Deaths, J Anal Toxicol (2017)
- Hudson S et al.: μ-Receptor Affinity Study (PMID 33091380)
- Mohr AL et al.: Furanylfentanyl Fatalities, J Anal Toxicol 40(9):709-717 (2016)
- PubChem: 11957557
- PubChem: Furanylfentanyl (CID 13653606)
UNODC: Fentanyl Analogues Identification Methods (2017)- Watanabe et al.: Furanylfentanyl Metabolism, Forensic Toxicol (2017)
Article Status
Step 1 · Automated synthesisAn autonomous workflow built by Josie Kins compiled this article's foundation from information published across the web.
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A first pass manual review and edit of article prose and copy has been performed by subject-matter expert Lyrea. This does not guarantee factual accuracy. An additional human review for each of this article's citations is yet to be performed.
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No one has reviewed this article's citations yet. That second pass checks each claim against the source it cites.
Recent changes8 human edits · latest
Times are UTCNewest first
16 August 2026
Lyrea · Added a citation in Pharmacology › Pharmacokinetics
Lyrea · Reworded 37 words in Pharmacology › Pharmacokinetics
Lyrea · Reworded 6 words in Pharmacology › Pharmacokinetics
Lyrea · Reworded 2 words in Pharmacology › Pharmacokinetics
Lyrea · Added a source: In Vitro and In Vivo Metabolite Identification Studies for the New Synthetic Opioids Acetylfentanyl, Acrylfentanyl, Furanylfentanyl, and 4-Fluoro-Isobutyrylfentanyl
24 January 2026
Josie Kins · Updated the article · also 1,4-Butanediol, 1B-LSD, 1cP-AL-LAD and 573 more
Josie Kins · Updated the article · also 1,4-Butanediol, 1B-LSD, 1cP-AL-LAD and 573 more
Josie Kins · Updated the article · also 1,4-Butanediol, 1B-LSD, 1cP-AL-LAD and 573 more
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