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Death may occur when Acetylfentanyl is combined with depressants such as opiates, benzodiazepines, barbiturates, gabapentinoids, thienodiazepines or other GABAergic substances.[1]

It is strongly discouraged to combine either heavy or moderate dosages of these substances together.

Summary sheet: Acetylfentanyl
Chemical Nomenclature
Common names Acetylfentanyl
Systematic name N-(1-Phenethylpiperidin-4-yl)-N-phenylacetamide
Class Membership
Psychoactive class Opioid
Chemical class Piperidine
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 2 - 5 mg
Light 5 - 10 mg
Common 10 - 15 mg
Strong 15 - 20 mg
Heavy 20 mg +
Total 1 - 4 hours
Onset 20 - 40 minutes
Threshold 2 - 5 mg
Light 5 - 10 mg
Common 10 - 15 mg
Strong 15 - 20 mg
Heavy 20 mg +
Total 3 - 4 hours
Onset 7 - 10 minutes

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.

Serotonin releasers
Selective serotonin re-uptake inhibitors
Serotonin-norepinephrine reuptake inhibitors

Acetylfentanyl is a synthetic opioid substance of the piperidine chemical class that produces analgesic, anxiety suppressing, and euphoric effects when administered. It is a structural analog of fentanyl. Studies have estimated acetylfentanyl to be between five to fifteen times more potent than heroin, eighty times more potent than morphine, and fifteen times less potent than its parent compound, fentanyl.[2][3]

This compound has never been licensed for medical use and has only been sold as a designer drug. Acetylfentanyl was discovered at the same time as fentanyl and was rarely encountered on the illicit market in the late 1980s as it was never commonly used. However, recently in 2013, Canadian police discovered a group distributing over 3 kilograms and 12,400 pills of acetylfentanyl (equal to 117,400 doses).[citation needed]

As a μ-opioid receptor agonist, acetylfentanyl may serve as a direct substitute for heroin or other μ-opioid receptor agonist substances. The side effects of fentanyl analogs are similar to those of fentanyl itself, which include itchiness, nausea and potentially fatal respiratory depression. On the street market, it and its analogs are often misrepresented as traditional opioids like heroin due to its increased potency and substantially lower production costs.[citation needed]

Fentanyl analogs have killed hundreds of people throughout Europe and the former Soviet republics since the most recent resurgence in use began in Estonia in the early 2000s.[4][5]

It is highly advised to use harm reduction practices such as volumetric dosing if choosing to use this substance.


Acetylfentanyl is a member of the phenylpiperdine class of synthetic opioids. Its structure features a piperidine ring bound at its nitrogen constituent RN to a phenyl ring through an ethyl chain. The opposite carbon of the piperidine ring is bonded to the nitrogen member of a acetamide group, a two carbon chain with a nitrogen constituent adjacent to a carbon bonded to a ketone oxygen. This acetamide group is also substituted with an additional phenyl ring at RN. Acetylfentanyl is a structural homologue to fentanyl, with one less carbon on its amide chain.


The recreational effects of this compound occur because opioids structurally mimic endogenous endorphins which are naturally found within the body and also work upon the μ-opioid receptor set. The way in which opioids structurally mimic these natural endorphins results in their physical euphoria, pain relief and anxiolytic effects. This is because endorphins are responsible for reducing pain, causing sleepiness, and feelings of pleasure. They can be released in response to pain, strenuous exercise, orgasm, or general excitement.

Acetylfentanyl's strong potency in relation to that of morphine is largely due to its high lipophilicity, which is the ability of a chemical compound to dissolve in fats, oils, and lipids. Because of this, it can more easily penetrate the central nervous system in comparison to other opioids.

Subjective effects

The effects listed below are based upon the subjective effects index and personal experiences of PsychonautWiki contributors. These effects should be taken with a grain of salt and will rarely (if ever) occur all at once, but heavier doses will increase the chances of inducing a full range of effects. Likewise, adverse effects become much more likely on higher doses and may include serious injury or death.

Physical effects

Cognitive effects

Visual 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

Fentanyl analogs have killed hundreds of people throughout Europe and the former Soviet republics since the most recent resurgence in use began in Estonia in the early 2000s, and novel derivatives continue to appear.[6][7][8]

The United States Drug Enforcement Administration reported in July of 2015 that at least 52 confirmed fatalities involving acetylfentanyl in the United States had occurred between 2013-2015. Ten fatalities attributed to acetylfentanyl overdose were reported during March of 2013 alone in Rhode Island. [9]

Fentanyl is potentially fatal at heavy dosages and even those with opiate tolerances are at high risk for overdoses. Once the acetylfentanyl is in the user's system, it is extremely difficult to stop its course because of the nature of absorption. Because of the extremely high strength of pure acetylfentanyl powder, it is very difficult to dilute appropriately, and often the resulting mixture may be far too strong and, therefore, very dangerous. It is also potentially lethal when mixed with depressants like alcohol or benzodiazepines.

Like most opioids, unadulterated acetylfentanyl at appropriate dosages does not cause many long-term complications other than extreme physical dependence and constipation. Outside of physical and psychological addiction, the harmful aspects of opioid usage are associated with not taking the necessary precautions in regards to its administration, overdosing on the substance and using impure products within the substance. It is important to consider that particular care must be taken with acetylfentanyl due to its extreme potency and ability to be absorbed through the skin. This means that simply unintentionally spilling a very small amount of acetylfentanyl on one's skin could result in a fatal overdose.

Heavy dosages of acetylfentanyl can result in respiratory depression, leading onto fatal or dangerous levels of anoxia (oxygen deprivation). This occurs because the breathing reflex is suppressed by agonism of μ-opioid receptor proportional to the dosage consumed.

Acetylfentanyl can also cause nausea and vomiting; a significant number of deaths attributed to opioid overdose are caused by aspiration of vomit by an unconscious victim. This is when an unconscious or semi-conscious user who is lying on their back vomits into their mouth and unknowingly suffocates. It can be prevented by ensuring that one is lying on their side with their head tilted downwards so that the airways cannot be blocked in the event of vomiting while unconscious (also known as the recovery position). In case of overdose, it is advised to administer a dose of naloxone intravenously or intramuscularly to reverse the effects of opioid agonism.

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

Tolerance and addiction potential

As with other opioids, the chronic use of acetylfentanyl can be considered extremely addictive with a high potential for abuse and is capable of causing psychological dependence among certain users. When addiction has developed, cravings and withdrawal symptoms may occur if a person suddenly stops their usage.

Tolerance to many of the effects of acetylfentanyl develops with prolonged and repeated use. The rate at which this occurs develops at different rates for different effects, with tolerance to the constipation-inducing effects developing particularly slowly for instance. This results in users having to administer increasingly large doses to achieve the same effects. After that, it takes about 3 - 7 days for the tolerance to be reduced to half and 1 - 2 weeks to be back at baseline (in the absence of further consumption). Acetylfentanyl presents cross-tolerance with all other opioids, meaning that after the consumption of acetylfentanyl all opioids will have a reduced effect.

The risk of fatal opioid overdoses rise sharply after a period of cessation and relapse, largely because of reduced tolerance.[10] To account for this lack of tolerance, it is safer to only dose a fraction of one's usual dosage if relapsing. It has also been found that the environment one is in can play a role in opioid tolerance. In one scientific study, rats with the same history of heroin administration were significantly more likely to die after receiving their dose in an environment not associated with the drug in contrast to a familiar environment.[11]

Dangerous interactions

Although many drugs are safe on their own, they can become dangerous and even life-threatening when combined with other substances. The list below contains some common potentially dangerous combinations, but may not include all of them. Certain combinations may be safe in low doses of each but still increase the potential risk of death. Independent research should always be done to ensure that a combination of two or more substances is safe before consumption.

  • Depressants (1,4-Butanediol, 2m2b, alcohol, barbiturates, benzodiazepines, GHB/GBL, methaqualone) - This combination can result in dangerous or even fatal levels of respiratory depression. These substances potentiate the muscle relaxation, sedation and amnesia caused by one another and can lead to unexpected loss of consciousness at high doses. There is also an increased risk of vomiting during unconsciousness and death from the resulting suffocation. If this occurs, users should attempt to fall asleep in the recovery position or have a friend move them into it.
  • Dissociatives - This combination can result in an increased risk of vomiting during unconsciousness and death from the resulting suffocation. If this occurs, users should attempt to fall asleep in the recovery position or have a friend move them into it.
  • Stimulants - It is dangerous to combine acetylfentanyl, a depressant, with stimulants due to the risk of excessive intoxication. Stimulants decrease the sedative effect of acetylfentanyl, which is the main factor most people consider when determining their level of intoxication. Once the stimulant wears off, the effects of acetylfentanyl will be significantly increased, leading to intensified disinhibition as well as other effects. If combined, one should strictly limit themselves to taking a certain amount of acetylfentanyl.

Serotonin syndrome risk

Combinations with the following substances can cause dangerously high serotonin levels. Serotonin syndrome requires immediate medical attention and can be fatal if left untreated.



This legality section is a stub.

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

  • Canada - It is a Schedule 1 drug[13] as it is an analog of fentanyl[14] and all fentanyl analogs are Schedule 1.
  • China - As of October 2015, acetylfentanyl is a controlled substance in China.[15]
  • Germany: Acetylfentanyl is controlled under BtMG Anlage II, making it illegal to manufacture, import, possess, sell, or transfer it without a license.[16]
  • United States - Acetylfentanyl is a Schedule I controlled substance as of May 2015.[17] The illegality of the drug has been supported by the charges against individuals for distribution of acetylfentanyl and possession with the intent to distribute acetylfentanyl.[18] One individual was sentenced to 3 years in prison by a federal court.
  • Switzerland - Acetylfentanyl is illegal in Switzerland as of December 2015.[19]
  • United Kingdom - Acetylfentanyl was made a class A drug as an analogue of fentanyl in 1986.[20]

See also

External links


  1. Risks of Combining Depressants (Tripsit) |
  2. P. A. J. Janssen and C. A. M. van der Eycken in Drugs Affecting the Central Nervous System, Vol. 2, A. Burger, Ed., Marcel Dekker, New York, 1968, pp. 51-54.
  4. Mounteney, Jane; Giraudon, Isabelle; Denissov, Gleb; Griffiths, Paul (July 2015). "Fentanyls: Are we missing the signs? Highly potent and on the rise in Europe". International Journal of Drug Policy. 26 (7): 626–631. PMID 25976511.
  5. Ruangyuttikarn, Werawan; Law, Michael Y.; Rollins, Douglas E.; Moody, David E. (May–June 1990). "Detection of Fentanyl and its Analogs by Enzyme-Linked Immunosorbent Assay". Journal of Analytical Toxicology. 14 (3): 160–164. ISSN 0146-4760. PMID 2374405.
  6. Fentanyls: Are we missing the signs? Highly potent and on the rise in Europe ( / NCBI) |
  7. Detection of fentanyl and its analogs by enzyme-linked immunosorbent assay ( / NCBI) |
  8. Acetyl fentanyl overdose fatalities--Rhode Island, March-May 2013 ( / NCBI) |
  9. Acetylfentanyl Critical Review Report (World Health Organization)|
  10. Why Heroin Relapse Often Ends In Death - Lauren F Friedman (Business Insider) |
  11. Siegel, S., Hinson, R., Krank, M., & McCully, J. (1982). Heroin “overdose” death: contribution of drug-associated environmental cues. Science, 216(4544), 436–437.
  12. Gillman, P. K. (2005). Monoamine oxidase inhibitors, opioid analgesics and serotonin toxicity. British Journal of Anaesthesia, 95(4), 434-441.
  15. 关于印发《非药用类麻醉药品和精神药品列管办法》的通知 |
  17. 80 FR 29227 - Schedules of Controlled Substances: Temporary Placement of Acetyl Fentanyl into Schedule I |
  18. Two Charged With Witness Tampering In Joint Woonsocket Police, DEA Investigation |
  19. Verordnung des EDI über die Verzeichnisse der Betäubungsmittel, psychotropen Stoffe, Vorläuferstoffe und Hilfschemikalien |
  20. The Misuse of Drugs Act 1971 (Modification) Order 1986 |