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Substance education guide

Phenibut (β-Phenyl-γ-aminobutyric acid)

Synthetic GABA analogue · GABA-B agonist · α2δ calcium-channel ligand · Unregulated research chemical in the United States

· How it works

Classification and primary mechanism

Phenibut is a synthetic phenyl derivative of GABA. The added phenyl ring helps it cross the blood-brain barrier. It acts primarily as a GABA-B receptor agonist, similar to baclofen, and also binds the α2δ subunit of voltage-gated calcium channels like gabapentin and pregabalin. At high or toxic doses it may also affect GABA-A receptors.

· Immediate effects

Recognize the effects

Signs of Use

  • Delayed sedation, dizziness, or slowed thinking
  • Poor coordination, slurred speech, or unusual behavior
  • Nausea, vomiting, weakness, or reduced responsiveness
  • Agitation, hallucinations, tremors, or seizures during toxicity or withdrawal
  • Slow, shallow, or irregular breathing when combined with other depressants

Short Term

  • Anxiety reduction, relaxation, and sedation
  • Impaired judgment, balance, memory, and reaction time
  • Nausea, vomiting, confusion, or loss of consciousness at high doses
  • Respiratory depression and coma when combined with opioids, alcohol, benzodiazepines, or other sedatives

Long Term

  • Rapid tolerance and severe physical dependence
  • Withdrawal with rebound anxiety, insomnia, agitation, hallucinations, delirium, or seizures
  • Compulsive redosing driven by delayed onset and long duration
  • Unknown risks from unregulated formulations and contaminants

· Long-term consequences

Dangerous interactions

Do not combine phenibut with alcohol, opioids, benzodiazepines, carisoprodol, gabapentin, pregabalin, sleep medicines, or other CNS depressants. Combining GABAergic or respiratory-depressant substances can cause profound sedation, aspiration, respiratory failure, and death.

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