Beta test rollout. This site is in community QA — please send feature requests, bug reports and data corrections on the Feedback page or on GitHub.

Home
    Disclaimer
    Furanylfentanyl molecular structure

    Furanylfentanyl Stats & Data

    Fu-f furanyl-fentanyl
    NPS DataHub
    MW374.48
    FormulaC24H26N2O2
    CAS101345-66-8
    IUPACN-phenyl-N-[1-(2-phenylethyl)piperidin-4-yl]furan-2-carboxamide
    SMILESc1ccc(cc1)CCN1CCC(CC1)N(c1ccccc1)C(=O)c1ccco1
    InChIKeyFZJVHWISUGFFQV-UHFFFAOYSA-N
    Phenethylamines Opioids
    Chemical Class Anilidopiperidine
    Psychoactive Class Depressant

    Receptor Profile

    Receptor Actions

    Agonists
    μ-Opioid receptor agonist (full)

    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. Despite this early pharmacological characterization, the compound remained largely obscure outside of research contexts for several decades. The substance emerged on the illicit drug market in 2015, appearing as part of a broader proliferation of novel synthetic opioids. This wave of designer fentanyl analogs represented a continuation of trends that had begun in Estonia in the early 2000s, subsequently spreading throughout Europe and the former Soviet republics, where fentanyl derivatives had already caused hundreds of fatalities by the time furanylfentanyl appeared. By 2016, life-threatening adverse reactions attributed to furanylfentanyl had been documented in Sweden and Canada. In the United States, at least seven deaths in Cook County, Illinois were linked to the substance during 2016, with additional fatalities reported in suburban Chicago the following year. These incidents contributed to growing international concern regarding the rapid emergence of potent synthetic opioids on illicit drug markets.

    Effect Profile

    Curated + 2 Reports
    Opioid 7.0

    Strong euphoria and pain relief with strong itching/nausea, low sedation

    Euphoria / Warmth×3
    10
    Analgesia×2
    8
    Sedation / Relaxation×1
    3
    Itching / Nausea×1
    10
    Based on reports from:

    Tolerance & Pharmacokinetics

    drugs.wiki
    Half-Life
    ≈2–4 h (plasma elimination)
    Addiction Potential
    Very high; dependence and rapid tolerance develop after repeated exposure.

    No tolerance chart. Our decay curves for opioids were estimates, and a curve can make tolerance look longer-lasting than it is, which is the dangerous direction.

    Opioid tolerance drops fast when you stop, and even a few days off can be enough, so a dose that used to be normal can now stop your breathing. Overdose deaths rise sharply after prison, detox or leaving treatment, and tolerance also falls during a hospital stay. After any break, start with a much smaller amount, try a test dose first, don't use alone, and keep naloxone within reach. Alcohol, benzodiazepines, gabapentinoids and other sedatives make an opioid overdose much more likely.

    Sources: FRANK: heroin · National Harm Reduction Coalition · WHO: opioid overdose · Merrall et al. 2010 · Binswanger et al. 2007 · Strang et al. 2003 · FDA 2019: gabapentinoids and breathing

    Cross-Tolerances

    opioids

    Experience Report Analysis

    Erowid
    3 Reports
    2 Single-substance
    2016–2017 Date Range
    3 With Age Data

    Demographics

    Gender Distribution

    Too few reports for a chart: gender is known from 3 reports, and a split is drawn only from 20 reports or more. Counts are shown instead. Why 20?

    • Male 1 of 3
    • Not Specified 2 of 3

    Age Distribution

    Reports Over Time

    Form / Preparation

    Most common forms and preparations, as a share of the 2 reports that give one

    Too few reports for bars: these forms come from 2 reports, and a bar is drawn only from 20 reports or more. With fewer, a percentage cannot tell a common effect from a rare one. Counts are shown instead. Why 20?

    • Powder / Crystals 2 of 2

    Harm Reduction

    drugs.wiki

    Evidence from the EU Early Warning System shows furanylfentanyl has been sold as powders and liquids, including ready‑to‑use nasal sprays and e‑liquids, which can deliver unpredictable doses and increase overdose risk due to concentration errors and non‑uniform mixing. Carry naloxone and be prepared to give repeat doses: synthetic opioids often require redosing every 2–5 minutes and larger total amounts to restore breathing; the aim is ventilation, not full arousal, and medical help should be called immediately. Naloxone will not reverse the effects of non‑opioid adulterants such as xylazine or medetomidine, both of which have been frequently found alongside fentanyl‑class opioids; persistent heavy sedation after naloxone suggests these may be present and requires airway support and monitoring until help arrives. Fentanyl test strips can detect fentanyl and certain analogues at very low levels but are binary only and can give false positives or false negatives depending on sample composition and preparation; follow manufacturer or local drug‑checking instructions and do not assume a negative result means safety. Drug‑checking programs regularly find veterinary tranquilizers (xylazine, medetomidine), benzodiazepine‑related drugs, and multiple high‑potency opioids co‑present in expected fentanyl samples; co‑use greatly increases risk of respiratory depression and prolonged sedation. Because psychoactive doses are in the microgram range, volumetric dosing is strongly preferred over attempting to weigh single doses; use appropriately dilute solutions and labeled containers to reduce dosing error risk. Avoid using alone, avoid rapid redosing during the first 30–45 minutes, and be aware that re‑narcotization can occur after naloxone wears off (30–90 minutes), especially with long‑acting co‑depressants. Ready‑made nasal sprays purchased online or self‑prepared from powders have been seized in Europe; without analytical confirmation, assume concentration may vary bottle‑to‑bottle and within a bottle. Practice basic respiratory first aid during suspected overdose (rescue breaths while awaiting naloxone effect), and continue monitoring due to frequent polydrug contamination in current supplies. Treat any white powder or pressed tablet as potentially containing fentanyl‑class substances; test a small, well‑dissolved sample when possible and start with a sub‑threshold microdose to assess sensitivity.

    References

    Data Sources

    Additional references

    ← Back to Furanylfentanyl