yellow2 → orange2 → red2 → brown2 → yellow2
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WARNINGMIXING OR WITHDRAWAL CAN BE DANGEROUS
Ordinary doses in combination with other depressants can fatally stop breathing. After prolonged dependency, stopping suddenly can also cause seizures or delirium; seek medical help.
Phenibut
beta-phenyl-gamma-aminobutyric acid
Fenibut, Phenybut, PhGABA, Noofen, Anvifen
Phenibut is a depressant and anxiolytic of the gabapentinoid class, structurally derived from the neurotransmitter GABA. Developed in the Soviet Union during the 1960s under Professor V. V. Perekalin, it remains a prescribed pharmaceutical in Russia for conditions including anxiety, insomnia, depression, and PTSD. Outside Russia, it is unapproved for clinical use and typically sold as a nutritional supplement.citation needed At common doses, it is noted for producing less drowsiness than other GABAergic substances such as benzodiazepines.
Dosage & Duration
Dosage
Doses are population estimates that vary widely between individuals.
Threshold~0.25 g
Light0.5-1 g
Moderate1-2 g
Strong2-3.5 g
Heavy3.5+ g
The onset of effects is considerably slower than most other central nervous system depressants. To reduce the risk of accidental overdose, a minimum interval of two to three hours should be observed before considering any additional dose.
Duration
Onset1.5-3 hours
Come Up1.5-3 hours
Peak3-4 hours
Offset4-6 hours
After Effects6-24 hours
Total10-16 hours
Half-life
~5.3 hours
Subjective Effects
Legacy content. A statistically backed ontology from Mindstate Design Labs is coming soon.
In comparison to other commonly used GABAgenic depressants such as alcohol or benzodiazepines, this compound is significantly longer lasting, more euphoric and more recreational.
Physical
Cognitive
Pharmacology
Pharmacodynamics
Phenibut acts as a full agonist of the GABA-B receptor and as a blocker of α2δ subunit-containing voltage-dependent calcium channels (VDCCs), the latter mechanism being shared with gabapentinoids such as gabapentin and pregabalin.citation needed Phenibut's affinity for α2δ-containing VDCCs is higher than for the GABA-B receptor, and in rodent models, analgesic effects appear mediated by VDCC blockade rather than GABA-B agonism. Only (R)-phenibut has meaningful activity at GABA-B, while both enantiomers block VDCCs with similar potency. At higher doses, phenibut loses its GABA-B selectivity and gains additional activity as a GABA-A receptor agonist. Phenibut has also been reported to increase calcium-dependent spontaneous release of GABA in vitro, and its effects on dopamine remain unclear, with conflicting reports regarding whether it meaningfully raises dopamine levels.
Pharmacokinetics
Phenibut is not significantly metabolized and is largely excreted unchanged in the urine, with approximately 63-65% of the dose recovered renally.citation needed Following a single 250 mg oral dose in healthy volunteers, the elimination half-life was approximately 5.3 hours.
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.
DissociativesStimulants
Tolerance
Tolerance timelines are rules of thumb, not exact schedules, and vary widely between individuals and use patterns.
Full Tolerance
Tolerance to the sedative-hypnotic effects develops rapidly, typically within a couple of days of continuous use. Some users report noticeable tolerance after a single week of daily dosing. The Russian clinical literature indicates the substance is intended for only a few weeks of continuous use at the same dose due to this rapid tolerance development. Notably, tolerance to different effects may develop at different rates—sedative effects diminish while nootropic effects may be preserved or even enhanced with chronic dosing.
Baseline Reset
Full baseline tolerance is typically restored within 7-14 days of abstinence. Neuroadaptive changes to GABA receptor systems, including downregulation of GABA-B receptors and alterations in benzodiazepine and GABA-A receptor binding, have been observed to normalize within 24-48 hours after cessation in animal studies, though complete functional recovery in humans may take longer.
Half Tolerance
Tolerance begins to decrease after cessation, though specific half-tolerance timelines are not well-established in the literature.
Cross Tolerance
GABAergic depressants (benzodiazepines, alcohol, GHB), Other GABA-B agonists (baclofen)
Harm Potential
Addiction & Dependence
Psychological
ModeratePhenibut is moderately psychologically addictive, particularly with heavy or frequent use.citation needed The extended onset period can lead to compulsive redosing when users mistakenly believe the substance is not working, and rebound anxiety commonly drives continued use.
Physical
ModeratePhysical dependence develops with daily or near-daily use, sometimes within weeks of regular dosing.citation needed Withdrawal symptoms can be severe and include anxiety, insomnia, tremors, agitation, rapid heartbeat, nausea, vomiting, irritability, and fatigue. Baclofen has been used successfully to treat phenibut dependence.2
Toxicity
Hepatic
Prolonged use at high doses may cause fatty liver disease; doses above 7 grams have been associated with fatty liver degeneration in overdose cases.citation needed
Renal
Renal impairment has been reported in overdose cases; this is not a typical concern at standard doses.citation needed
Gastrointestinal
Phenibut hydrochloride is highly caustic and may cause intestinal discomfort, diarrhea, and potentially lower digestive tract bleeding in sensitive users.
Hematological
Eosinophilia has been reported with prolonged high-dose use and in overdose cases.citation needed
Psychosis Risk
Acute psychosis and visual/auditory hallucinations have been reported primarily as withdrawal symptoms in recreational users discontinuing heavy use, rather than during intoxication.citation needed Withdrawal-associated psychosis appears to occur in cases of abrupt cessation following prolonged high-dose use.
Seizure Risk
Tonic-clonic seizures have been reported in recreational users who have overdosed.citation needed Seizures are not a typical occurrence at standard doses and appear to be associated with significant overdose.
History & Culture
Development and Soviet Adoption
Phenibut was synthesized during the 1960s at the Department of Organic Chemistry at the Al Gertsen Leningrad Pedagogical Institute under the supervision of Professor V. V. Perekalin.3 Following its development, the compound was researched for potential…
Legality
International
Phenibut is not internationally scheduled under the 1961 Single Convention, the 1971 Convention on Psychotropic Substances, or the 1988 Convention against Illicit Traffic. The official convention schedules and INCB consolidated narcotic and psychotropic lists do not name phenibut, fenibut, or 4-amino-3-phenylbutanoic acid.
By Country
Illegal8
ArgentinaIllegalPhenibut (Fenibut; ácido 4-amino-3-fenilbutírico) is an individually listed estupefaciente in Argentina’s Anexo I to Decreto 560/2019. Decreto 122/2026 replaces that annex and keeps the national criminal-control list current; substances in the list are estupefacientes for article 77 of the Código Penal and the offences in Ley 23.737. Unauthorized production, possession, supply, and trafficking of a listed substance are therefore subject to Argentina’s narcotics-law prohibitions.
FranceIllegalArrêté du 9 septembre 2020 modifiant l'arrêté du 22 février 1990 fixant la liste des substances psychotropes12131415
Phenibut (acide 4-amino-3-phénylbutanoïque) is listed in France's list of psychotropic substances from 12 September 2020. Its production, manufacture, transport, import, export, possession, offer, transfer, acquisition, and use are prohibited unless expressly authorised under Article R. 5132-88 of the Code de la santé publique.
GermanyIllegal (analog/blanket ban)Phenibut (4-amino-3-phenylbutanoic acid) is covered by the NpSG’s Annex 1 structural group for compounds derived from 2-phenethylamine, rather than by an individual name. The NpSG prohibits trading, placing on the market, manufacture, import, export, acquisition, possession, and administration of covered substances, subject to statutory exemptions for recognised industrial, commercial, and scientific uses. The Act has been in force since 26 November 2016; the consolidated text is current through the amendment of 7 January 2026.
NetherlandsIllegal (analog/blanket ban)Phenibut is prohibited in the Netherlands as a substance derived from 2-phenethylamine under List IA of the Opium Act. The generic List IA prohibition has applied since 1 July 2025 and prohibits importing, exporting, preparing, processing, selling, supplying, transporting, possessing, and manufacturing substances in its listed structural groups. Phenibut’s 4-amino-3-phenylbutanoic-acid structure is a substituted 2-phenethylamine within that statutory group.
NorwayIllegalForskrift om narkotika (narkotikaforskriften), FOR-2013-02-14-199, as amended by FOR-2023-12-11-2000293031
Phenibut (fenibut; 4-amino-3-fenylbutansyre) is a narcotic in Norway because it is named in the Narkotikalisten, which was amended with immediate effect on 11 December 2023. Possession and use are prohibited without lawful authority. Manufacture, import, wholesale activity and retail sale require the applicable express authorisation, and narcotic supply, sale and dispatch are permitted only for medical and scientific use.
South AfricaIllegal (analog/blanket ban)Drugs and Drug Trafficking Act, 1992, as amended by the Drugs and Drug Trafficking Amendment Act 14 of 202232133
Phenibut is covered under Part III of Schedule 2 to the Drugs and Drug Trafficking Act, 1992, as substituted by the Drugs and Drug Trafficking Amendment Act 14 of 2022. Part III lists gamma-hydroxybutyrate (GHB) and extends coverage to chemically related substances with a similar structural fragment and/or similar pharmacodynamic properties; phenibut and GHB both act at GABA-B receptors. Dealing in or possessing a covered undesirable dependence-producing substance is prohibited unless authorized under the Act, and the substituted Schedule was published in Government Gazette 47736 on 14 December 2022.
Controlled / restricted2
United StatesRestrictedNot a federally scheduled substance. Legal to possess without license or prescription. Sales, distribution, and labeling are regulated by FDA rules when sold for human consumption.48 Note that Alabama classified phenibut as a Schedule II controlled substance at the state level as of November 21st, 2021.49
By state
Across the 50 states, D.C., and the permanent territories, most jurisdictions treat Phenibut consistently with federal control; listed entries record independently verified differences in state classification or coverage.
IowaNot scheduledIowa Code § 124.204 (Schedule I) and Iowa Code ch. 124 schedules50
Phenibut is not a scheduled controlled substance in Iowa. Iowa's controlled-substances chapter enumerates its scheduled substances and does not designate phenibut, fenibut, or beta-phenyl-gamma-aminobutyric acid.
KentuckyNot scheduled902 KAR 55:01551
Phenibut is not a designated controlled substance in Kentucky. Kentucky adopts federally scheduled substances into the corresponding state schedule and separately names its state-only designations; phenibut is in neither category.
MaineNot scheduled17-A M.R.S. § 110252
Phenibut is not scheduled in Maine's controlled-drug schedules. The statutory schedules enumerate the substances assigned to schedules W, X, Y, and Z and do not designate phenibut, fenibut, or beta-phenyl-gamma-aminobutyric acid.
MassachusettsNot scheduledM.G.L. c. 94C, § 3153
Phenibut is not classified as a controlled substance in Massachusetts. The Commonwealth's five statutory classes enumerate controlled substances and do not designate phenibut, fenibut, or beta-phenyl-gamma-aminobutyric acid.
MichiganNot scheduled
MinnesotaNot scheduledMinn. Stat. § 152.0256
Phenibut is not scheduled as a controlled substance in Minnesota. Minnesota's schedule statute lists substances by official, common, usual, chemical, or trade name, and its lists do not designate phenibut.
MissouriNot scheduledRSMo § 195.01757
Phenibut is not scheduled as a controlled substance in Missouri. Missouri's schedule statute lists Schedule I through V controlled substances and does not designate phenibut, fenibut, or beta-phenyl-gamma-aminobutyric acid.
NebraskaNot scheduledNeb. Rev. Stat. § 28-40558
Phenibut is not scheduled as a controlled substance in Nebraska. Nebraska's statutory schedules enumerate covered controlled substances and do not designate phenibut, fenibut, or beta-phenyl-gamma-aminobutyric acid.
NevadaNot scheduled
South DakotaIllegalSDCL § 34-20B-12(37), as amended by 2026 S.D. Sess. Laws ch. 148 (HB 1162)61
Phenibut is a Schedule I controlled substance in South Dakota. The Schedule I designation places it in the state controlled-substances regime rather than solely the federal food-and-drug restriction applicable nationally.
United KingdomRestrictedPhenibut is a psychoactive substance for the purposes of the Psychoactive Substances Act 2016 when it is not an exempted substance. The Act prohibits producing, supplying, offering to supply, importing, or exporting it where the statutory knowledge and intended psychoactive-consumption conditions are met. The Act does not create a general offence of simple possession outside a custodial institution; medicinal products and controlled drugs are among the statutory exemptions. The Medicines and Healthcare products Regulatory Agency describes phenibut as a central depressant and GABA analogue with anxiolytic effects.
Prescription2
New ZealandPrescription onlyPhenibut is a prescription medicine listed in Part 1 of Schedule 1 to the Medicines Regulations 1984. The current Schedule 1 was replaced by the Medicines Amendment Regulations (No 2) 2021, which came into force on 1 September 2021. Retail sale or supply of a prescription medicine is restricted by the Medicines Act 1981 to statutory routes and exemptions, including authorised prescribing and dispensing routes.
Not scheduled4
RussiaApproved pharmaceuticalAdded to the State Drug Register in 1974 under Order No. 1126 by the USSR Ministry of Public Health.3 Remains available as a neuropsychotropic medication for conditions including anxiety, depression, PTSD, insomnia, and vestibular disorders.
SwedenNot scheduledFörordning (1992:1554) om kontroll av narkotika; Förordning (1999:58) om förbud mot vissa hälsofarliga varor343536
Phenibut (4-amino-3-fenylbutansyra) is not named in the current annexes to Sweden's narcotics-control regulation or regulation on goods dangerous to health. Swedish narcotics and hazardous-goods controls apply to substances specified in those respective annexes. Sweden does not use analogue, effect-based, or generic chemical-structure definitions to classify narcotics or goods dangerous to health; the separately named 4-fluorophenibut entry does not extend to phenibut.
References
Source Pages
Citations
- Maija Dambrova, Liga Zvejniece, Edgars Liepinsh, Helena Cirule, Olga Zharkova, Grigory Veinberg, & Ivars Kalvinsh. (March 2008). Comparative pharmacological activity of optical isomers of phenibut. European Journal of Pharmacology, 583(1), 128–134. https://doi.org/10.1016/j.ejphar.2008.01.01512
- A Case of Phenibut Withdrawal Management and Detoxification Using Baclofen in the Outpatient Setting. (2024). https://pmc.ncbi.nlm.nih.gov/articles/PMC11239229/1
- Izyaslav Lapin. (2001). Phenibut (beta-phenyl-GABA): a tranquilizer and nootropic drug. CNS Drug Reviews, 7(4), 471–81. https://doi.org/10.1111/j.1527-3458.2001.tb00211.x12
- Decreto 560/2019, Anexo I, sustituido por Decreto 122/2026. boletinoficial.gob.ar (n.d.). https://www.boletinoficial.gob.ar/detalleAviso/primera/338915/20260302?anexos=11
- Decreto 560/2019, Anexo I, sustituido por Decreto 122/2026. servicios.infoleg.gob.ar (n.d.). https://servicios.infoleg.gob.ar/infolegInternet/anexos/325000-329999/326675/dec560-1.pdf1
- Decreto 560/2019, Anexo I, sustituido por Decreto 122/2026. argentina.gob.ar (n.d.). https://www.argentina.gob.ar/normativa/nacional/ley-23737-138/texto1
- Poisons Standard June 2018. legislation.gov.au (n.d.). https://www.legislation.gov.au/F2018L00625/latest/text1
- Poisons Standard June 2018. legislation.gov.au (n.d.). https://www.legislation.gov.au/F2018L00625/asmade/2018-05-17/text/original/epub/OEBPS/document_1/document_1.html1
- Final decisions and reasons for decisions by delegates of the Secretary to the Department of Health, October 2017 – Phenibut. Therapeutic Goods Administration, Australian Government Department of Health (2017). https://www.tga.gov.au/sites/default/files/final-decision-and-reasons-for-decision-by-delegate-october-2017.pdf1
- Controlled Drugs and Substances Act (Canada), consolidated to 2026-06-21. laws-lois.justice.gc.ca (n.d.). https://laws-lois.justice.gc.ca/eng/acts/c-38.8/FullText.html1
Further Reading
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Recent changes7 human edits · latest
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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
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
Josie Kins · Updated the article · also 1,4-Butanediol, 1B-LSD, 1cP-AL-LAD and 573 more
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