Phenibut
GABA-B agonist (anxiolytic)
What it is
A Soviet-developed anti-anxiety compound — a GABA analog that crosses the blood-brain barrier and acts mainly on GABA-B receptors (the same receptor family as baclofen). Sold online as a "nootropic" for anxiety and sleep.
What human evidence shows
Human evidence is thin and mostly Russian: small trials for anxiety and asthenia decades old. Western clinical literature about phenibut is dominated not by efficacy studies but by case reports of dependence and withdrawal — which is itself the evidence picture worth knowing.
Risks
The standout risk in this entire list for dependence: tolerance builds within weeks of regular use, and withdrawal — documented in numerous case reports — can be severe (rebound anxiety, insomnia, agitation, psychosis in the worst cases) and medically complicated. Combining with alcohol or other depressants adds respiratory-depression risk. Poison-control calls for phenibut rose sharply through the 2010s.
Legal status
US: unscheduled federally but NOT a lawful dietary ingredient (FDA has warned sellers); banned in a few states. Prescription drug in Russia; controlled in Australia and Hungary.
Evidence base
substantial literature
Real human evidence: randomised trial reports, or review-level evidence backed by at least one human trial report.
- phase 3/4
- 0
- randomised
- 1
- reviews
- 3
- human trials
- 4
Counts are of published papers, not distinct trials, and measure how much research exists — not whether this works or is safe for you.
Research (12)
- Phenibut: A drug with one too many "buts"Basic Clin Pharmacol Toxicol · 2024
- Phenibut: Review and Pharmacologic Approaches to Treating WithdrawalJ Clin Pharmacol · 2024
- A Systematic Review of Phenibut WithdrawalsCureus · 2024
- Phenibut (β-Phenyl-γ-Aminobutyric Acid): an Easily Obtainable "Dietary Supplement" With Propensities for Physical Dependence and AddictionCurr Psychiatry Rep · 2019
- Clinical Presentations and Treatment of Phenibut Toxicity and Withdrawal: A Systematic Literature ReviewJ Addict Med · 2023
- A systematic review of phenibut withdrawal focusing on complications, therapeutic approaches, and single substance versus polysubstance withdrawalClin Toxicol (Phila) · 2023
- Phenibut overdoseAm J Emerg Med · 2017
- Phenibut (beta-phenyl-GABA): a tranquilizer and nootropic drugCNS Drug Rev · 2001
- Acute phenibut withdrawal: A comprehensive literature review and illustrative case reportBosn J Basic Med Sci · 2019
- Quantity of phenibut in dietary supplements before and after FDA warningsClin Toxicol (Phila) · 2022
- Phenibut withdrawal management in a neonatePediatr Neonatol · 2022
- Phenibut Dependence and WithdrawalPrim Care Companion CNS Disord · 2021
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