Phenibut Facts
Depressant;
Description
Phenibut (4-amino-3-phenylbutanoic acid) is a synthetic depressant of the gabapentinoid class. It calms the brain by activating GABA receptors and suppressing calcium-channel signaling, producing its characteristic anxiolysis and sedation.[1][2]
Subjective effects include anxiolysis, euphoria, sociability, and sedation.[3] The experience is a warm, socially lubricating calm — less impairing than alcohol, with a clean sense of well-being at lower doses.
Phenibut produces rapid physical dependence — tolerance builds within days — though no confirmed fatalities from phenibut alone appear in published literature.[4][5] Doses commonly escalate far above therapeutic levels, and stopping abruptly can trigger delirium, hallucinations, and seizures.[6][7]
Dose and durationby route · individual sensitivity varies
Starts in 1.5 – 3 hoursLasts 10 – 16 hoursAfter-effects 6 – 24 hours
Body and dependence
- Acute toxicity
- Moderate
- Chronic toxicity
- High
- Physical dependence
- High
- Psychological dependence
- High
- Withdrawal
- Severe · medical supervision
- Compulsive redosing
- Moderate
Tolerance
- Builds
- Rapid
- Fully resets after
- Not recorded
- Carries over to
- baclofen;
gabapentin; pregabalin; benzodiazepines
Effectslikely at a common dose
- Perception
- none likely · 3 possible
- Body
- Sedation;
+14 possible, including Motor control impairment, Dizziness, Insomnia - Thinking
- none likely · 13 possible, including Compulsive redosing urge, Cognitive impairment, Analysis suppression
- Feeling
- Anxiety suppression;
+8 possible, including Anxiety, Dysphoria, Depression - Self
- none likely · 5 possible, including Craving
Who shouldn't take it
Combinations60 recorded
Seek help immediately if
- Extreme drowsiness — can't stay awake or be roused
- Confusion, slurred speech, severe loss of coordination
- Slow, shallow, or irregular breathing
- Unconsciousness / unresponsive; limp, floppy body
- Blue lips or fingertips
- Vomiting while sedated (choking / aspiration risk)
- Cold, clammy skin; weak pulse
What to do
- Try to wake them — shout, firm sternal rub
- If unresponsive or breathing is impaired, call emergency services
- Place them in the recovery position — critical, they can choke on vomit
- Monitor breathing continuously; be ready to give rescue breaths / CPR
- Never leave them alone to "sleep it off"
- Do not give other drugs, stimulants, or more depressants
Most depressant overdoses resolve with airway protection, breathing support, and monitoring. The danger is respiratory depression and choking on vomit — sharply worse when combined with opioids or alcohol. GHB/GBL overdoses often involve sudden deep unconsciousness and may self-resolve, but airway protection is essential.
988 Suicide & Crisis LifelineFireside Project: 62-FIRESIDE
References
- [1]^Dambrova M, Zvejniece L, Liepinsh E, Cirule H, Zharkova O, Veinberg G, Kalvinsh I (2008) Comparative pharmacological activity of optical isomers of phenibut — European Journal of Pharmacology doi:10.1016/j.ejphar.2008.01.015
- [2]^Zvejniece L, Vavers E, Svalbe B, Veinberg G, Rizhanova K, Liepins V, Kalvinsh I, Dambrova M (2015) R-phenibut binds to the alpha2-delta subunit of voltage-dependent calcium channels and exerts gabapentin-like anti-nociceptive effects — Pharmacology, Biochemistry, and Behavior doi:10.1016/j.pbb.2015.07.014
- [3]^Lapin I (2001) Phenibut (beta-phenyl-GABA): a tranquilizer and nootropic drug — CNS Drug Reviews PMID:11830761
- [4]^Jouney EA (2019) Phenibut (beta-Phenyl-gamma-Aminobutyric Acid): an Easily Obtainable Dietary Supplement With Propensities for Physical Dependence and Addiction — Current Psychiatry Reports doi:10.1007/s11920-019-1009-0
- [5]
- [6]^Samokhvalov AV, Paton-Gay CL, Balchand K, Rehm J (2013) Phenibut dependence — BMJ Case Reports doi:10.1136/bcr-2012-008381