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evidence · mechanism · dose
Supplements/Nootropic

Phenibut (caution)

GABA-B agonist with high abuse and dependence potential; restricted in many countries.

Mood & AnxietySleep & Recovery

Overview

GABA-B agonist with high abuse and dependence potential; restricted in many countries.

Natural sources
  • Synthetic
Common forms
  • Phenibut HCl
  • F.A.A.

Forms & variants of Phenibut (caution)

Different chemical forms of Phenibut (caution) behave differently. Browse each form's mechanism, bioavailability, and best-use context.

Reference dose
Phenibut (Ref)

GABA-B agonist developed in the USSR for anxiety (caution).

Mechanism of action

GABA-B receptor agonist (like baclofen).

Pathways
  • · GABA-B agonism
Neurotransmitters
  • · GABA

Effects on the body

Decreases
Anxiety (short term)

Organ system effects

Brain & CNS

Severe tolerance and withdrawal.

Evidence-based benefits

Anxiolytic short-term

Limited evidence

Potential side effects

Common
  • · Drowsiness
Rare
    Serious
    • · Severe withdrawal syndrome
    • · Dependence
    • · Overdose with alcohol

    Drug interactions

    Alcohol / benzos / opioids
    Severe additive sedation / respiratory depression.
    severe

    Safety & non-supplemental interactions

    Educational summary — always confirm with your clinician or pharmacist before starting, stopping, or combining with prescription therapy.

    Avoid if you are
    • ·Pregnant or breastfeeding (insufficient safety data)
    • ·Children under 18 (unless directed by a clinician)
    Avoid / monitor with these medications
    • ·Alcohol, benzodiazepines, opioids, sedating antihistamines (additive CNS depression)

    Supplement interactions

    Pairs well with

    None listed.

    Avoid combining with
    • Regular use
      Severe withdrawal and dependence.
    • Alcohol
      Life-threatening interaction.

    Dosing & bioavailability

    Typical dose
    Not recommended; if used: ≤500 mg, max 2×/week

    Where to buy

    Affiliate-style search links to reputable retailers. We don't endorse specific brands — verify third-party testing (USP, NSF, Informed Sport) before purchase.

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    iHerb
    Global delivery · curated brands
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    Thorne
    Practitioner-grade · NSF tested

    Scientific evidence (8)

    Systematic reviewCNS Drug Rev · 2001

    Phenibut pharmacology and clinical use

    Lapin I

    Review of phenibut's GABA-B activity and uses.

    Key findings

    Anxiolytic effects; tolerance and withdrawal risks documented.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: Phenibut (caution) — Anxiolytic short-term

    Live PubMed search

    Live results for "Phenibut (caution) Anxiolytic short-term" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    Opens current human and preclinical literature matching Phenibut (caution) and "Anxiolytic short-term". Filter by RCT, meta-analysis, or year on the results page.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: Phenibut (caution) — randomized controlled trial

    Live PubMed search

    Live results for "Phenibut (caution) randomized controlled trial" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    Opens current human and preclinical literature matching Phenibut (caution) and "randomized controlled trial". Filter by RCT, meta-analysis, or year on the results page.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: Phenibut (caution) — meta-analysis

    Live PubMed search

    Live results for "Phenibut (caution) meta-analysis" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    Opens current human and preclinical literature matching Phenibut (caution) and "meta-analysis". Filter by RCT, meta-analysis, or year on the results page.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: Phenibut (caution) — pharmacokinetics

    Live PubMed search

    Live results for "Phenibut (caution) pharmacokinetics" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    Opens current human and preclinical literature matching Phenibut (caution) and "pharmacokinetics". Filter by RCT, meta-analysis, or year on the results page.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: Phenibut (caution) — safety adverse events

    Live PubMed search

    Live results for "Phenibut (caution) safety adverse events" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    Opens current human and preclinical literature matching Phenibut (caution) and "safety adverse events". Filter by RCT, meta-analysis, or year on the results page.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: Phenibut (caution) — dose response

    Live PubMed search

    Live results for "Phenibut (caution) dose response" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    Opens current human and preclinical literature matching Phenibut (caution) and "dose response". Filter by RCT, meta-analysis, or year on the results page.

    Open study
    Systematic reviewGoogle Scholar · 1970

    Google Scholar: Phenibut (caution) — clinical evidence

    Live Scholar search

    Cross-database citation index for Phenibut (caution) as it relates to "clinical evidence".

    Key findings

    Includes preprints, theses, and journal articles. Useful for tracking citation counts and follow-on work.

    Open study
    Educational use only. This profile is not medical advice. Consult a qualified healthcare professional before starting any supplement, especially if you take prescription medication or have a chronic condition.