Rankings / Mood, Anxiety & Stress
Phenibut (β-phenyl-GABA)
Mood, Anxiety & Stress · GABA-B agonist (with weak GABA-A activity)
Tier D
What this is
Popular among biohackers for social anxiety / public speaking / occasional use. Tolerance to anxiolytic effect develops within days; rebound anxiety on cessation. Severe withdrawal protocol-dependent (taper with baclofen as cross-tolerant agent). Highest-risk substance commonly recommended in nootropic forums. FDA April 2026 Addall alert found phenibut in a dietary supplement and reiterated addiction, withdrawal, loss of consciousness, and dangerous interaction risks. Use 1-2x/week MAX or risk dependence.
Mechanism
Russian-developed (1960s) GABA analog with a phenyl ring that allows BBB penetration; full GABA-B receptor agonist (similar to baclofen) plus weak GABA-A modulation; anxiolytic, prosocial, mildly euphoric at higher doses
Dose & route
250-1000 mg PO no more than 1-2x/week (definitively NOT daily)
Citations
- https://pubmed.ncbi.nlm.nih.gov/30707892/
- https://pubmed.ncbi.nlm.nih.gov/30457251/
- https://pubmed.ncbi.nlm.nih.gov/29381102/
- https://www.fda.gov/food/alerts-advisories-safety-information/fda-advises-consumers-retailers-and-distributors-not-eat-sell-or-distribute-addall-xr-shot-or-addall
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This is an independent synthesis of published research by a non-clinician. Scores are opinions supported by citations, not prescriptions. See the full disclaimer and methodology for how this score was produced and what it does and doesn't mean.