Chemical Compound

Phenibut

beta-Phenyl-gamma-aminobutyric acid

Evidence TierDWADA NOT PROHIBITED

tuneTypical Dose

0.25-2 g/day in formal clinical discussion contexts

watchEffect Window

Most short-term effects are same-day to next-day. Withdrawal risks emerge with repeated exposure.

check_circleCompliance

WADA NOT PROHIBITED

Overview

Clinical Summary

Phenibut is a GABA-B agonist with some anxiolytic history, but dependence, withdrawal, and product-quality risk make it a poor candidate for unsupervised use.

Short-term anxiolytic and sleep-promoting effects are plausible and are reflected in older clinical literature and user reports about reduced stress reactivity or sociability. But those details are constrained by what matters more in practice: rapid tolerance, medically significant withdrawal, and large variation in the amount actually present in products sold as supplements.

Likely GABA-B agonist with sedative and anxiolytic-like signaling. Efficacy appears dose-sensitive and high-risk with repeated exposure.

Outcomes

What This Is Expected To Influence

Primary Outcomes

  • Possible short-term anxiety reduction in selected clinical settings

Secondary Outcomes

  • Sedation/mood-modulation signals

Safety

Contraindications and Interactions

Contraindications

  • Pregnancy
  • Lactation
  • Severe psychiatric illness
  • Hepatic/renal failure
  • Substance use disorder

Side effects

  • Drowsiness
  • Nausea
  • Dizziness
  • Dependence risk
  • Withdrawal syndrome

Interactions

  • Alcohol
  • Opioids
  • Benzodiazepines
  • Sedative-hypnotics
  • Gabapentinoids

Avoid if

  • Children
  • Unstable cardiovascular disease
  • Seizure risk
  • Active polysubstance use

Evidence

Study-level References

phenibut-SRC-001Systematic review (11 clinical trials + 14 case reports)
Sourceopen_in_new

Einars Kupats et al. "Safety and Tolerability of the Anxiolytic and Nootropic Drug Phenibut: A Systematic Review of Clinical Trials and Case Reports." Pharmacopsychiatry. 2020;53(5):201-208. PMID: 32340063, DOI: 10.1055/a-1151-5017.

Population: Adults; mixed indications and trial contexts

Dose protocol: Review-level therapeutic ranges (0.25-2 g/day reported). Case reports include misuse doses substantially above this.

Key findings: 11 clinical trials (583 participants) and 14 case reports showed inconsistent benefit-confidence alignment. Controlled safety profiles were cleaner than misuse case patterns, but concern remains high for repeated exposure.

Notes: Good source for risk stratification. Low confidence for broad benefit claims.

Paper content

11 clinical trials (583 participants) and 14 case reports showed inconsistent benefit-confidence alignment; controlled safety profiles were cleaner than misuse case patterns, but concern remains high for repeated exposure.

phenibut-SRC-002Review article (clinical overview + misuse analysis)
Sourceopen_in_new

Edward A Jouney. "Phenibut ... with propensities for physical dependence and addiction." Current Psychiatry Reports. 2019;21(4):23. PMID: 30852710, DOI: 10.1007/s11920-019-1009-0.

Population: Clinical and public-safety populations

Dose protocol: Clinical use context mixed with non-prescribed misuse contexts

Key findings: Strong safety signal for dependence and withdrawal risk with prolonged misuse. Calls for tight use governance.

Notes: Not a positive efficacy trial, but central for harm and protocol constraints.

Paper content

Strong safety signal for dependence and withdrawal risk with prolonged misuse; calls for tight use governance.

phenibut-SRC-003Analytical market-surveillance study
Sourceopen_in_new

Cohen PA, et al. "Quantity of phenibut in dietary supplements before and after FDA warnings." Clin Toxicol (Phila). 2022;60(4):477-480. PMID: 34550038. DOI: 10.1080/15563650.2021.1973020.

Population: Four over-the-counter dietary supplement brands labeled as containing phenibut

Dose protocol: Laboratory analysis of over-the-counter products before and after FDA warning activity

Key findings: Detected phenibut content ranged from 21 mg to 1164 mg per serving, and some products contained more phenibut after FDA warning activity than before.

Notes: Important for real-world risk because supplement labels do not reliably predict exposure.

Paper content

This paper is a key real-world safety anchor for phenibut because it moves beyond case reports and shows that commercial supplement products do not provide stable or trustworthy exposure. After FDA warning activity, some products contained more phenibut than before, and the range per serving was extremely wide.

For a compound already associated with dependence, withdrawal, delirium, and overdose risk, that label unreliability materially worsens the user-risk profile.

Guides

Setup

Help