Phenibut
A GABA-B agonist and alpha-2-delta voltage-gated calcium channel blocker developed in Russia for anxiety, insomnia, and PTSD. It crosses the blood-brain barrier (unlike GABA supplements) and produces potent anxiolytic and social confidence effects. However, it carries significant addiction and withdrawal risks — tolerance develops within days of daily use, and withdrawal can be severe.
Dosage
Standard: 250-1000 mg on an empty stomach, no more than 1-2 times per week. NEVER use daily — tolerance and dependence develop within 3-5 days of consecutive use. Onset: 2-4 hours (slow). Do not exceed 2000 mg per occasion.
Dosages shown are for research reference only. Always consult a qualified healthcare provider.
Half-Life
5-6 hours
Administration
Oral (powder, capsules). Take on an empty stomach — food significantly reduces absorption. Slow onset (2-4 hours).
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Mechanism of Action
Phenibut is a structural analog of GABA with a phenyl ring that confers lipophilicity and allows blood-brain barrier penetration (unlike GABA itself). It acts as a GABA-B receptor agonist, binding to the GABAB1/GABAB2 heterodimer and activating Gi/o-coupled signaling (similar to baclofen), producing anxiolytic, muscle relaxant, and sedative effects through inhibition of adenylyl cyclase and modulation of potassium and calcium channels. Phenibut also blocks the alpha-2-delta-1 and alpha-2-delta-2 subunits of voltage-gated calcium channels, reducing presynaptic calcium influx and neurotransmitter release (similar to gabapentin/pregabalin). The dual mechanism—GABA-B agonism dampening inhibitory interneurons and calcium channel blockade reducing excitatory transmission—produces potent anti-anxiety and sleep-promoting effects. Rapid tolerance develops due to receptor downregulation.
Regulatory Status
Prescription medication in Russia, Latvia, and some CIS countries. Unregulated in the US (sold as a supplement). Banned or restricted in Australia, Hungary, Lithuania, and Italy. Not FDA-approved.
Risks & Safety
Common
Drowsiness, dizziness, nausea, tolerance with repeated use.
Serious
Physical dependence develops rapidly with daily use. Withdrawal can be severe and dangerous (anxiety, insomnia, psychosis, seizures). Respiratory depression when combined with alcohol or other CNS depressants.
Rare
Hallucinations, severe rebound anxiety, suicidal ideation during withdrawal.
Compare Phenibut With
Research Papers
10Published: February 6, 2001
AI Summary
Comparison of phenibut with piracetam and diazepam reveals similarities and differences in their pharmacological and clinical effects. Phenibut is widely used in Russia to relieve tension, anxiety, and fear, to improve sleep in psychosomatic or neurotic patients; as well as a pre- or post-operative medication.
Published: October 27, 2024
AI Summary
Ingestion of phenibut was often associated with concomitant use of other substances of abuse. As control over its online marketing seems unrealistic, current efforts need to be focused on the addition of phenibut to current drug screening tests and the development of generally accepted treatment strategies for phenibut-associated toxicities.
Published: June 9, 2024
AI Summary
Increased public awareness of phenibut has led to a growing number of reports of acute intoxication and withdrawal. As long as phenibut remains legal, cases of phenibut intoxication and withdrawal are likely to increase.
Published: February 2, 2023
AI Summary
This systematic review aimed to identify published articles that evaluated all phenibut toxicity and withdrawal cases to understand better their clinical presentations and treatments.
Published: September 5, 2024
AI Summary
Descriptive statistics were used to analyze the results. Phenibut is never prescribed in the United States, and there are no official guidelines for phenibut use.
Published: November 18, 2023
AI Summary
Use of phenibut can lead to dependence and subsequent withdrawal when use is stopped. Phenibut withdrawal can cause severe symptoms such as delirium, hallucinations, and seizures.
Published: March 8, 2019
AI Summary
Its use is growing in popularity, but its pharmacological activity is well beyond that of a conventional nutritional supplement, and similar to that of a prescription strength sedative. This review will focus on the potential adversities of phenibut use and will discuss what treatment options may be beneficial to afflicted patients.
Published: April 21, 2022
AI Summary
More than 80 cases of coma and death have been associated with phenibut consumption and withdrawal, and the FDA recently warned that the drug is not permitted in over-the-counter supplements. We designed our study to determine the presence and quantity of phenibut in over-the-counter supplements before and after the FDA warnings.
Published: February 17, 2021
AI Summary
Abstract too short to summarize.
Published: July 11, 2023
AI Summary
To describe the successful treatment of severe neurological and cardiovascular abnormalities in a dog following ingestion of the neuropsychotropic drug, phenibut.
Frequently Asked Questions
What is Phenibut used for?
A GABA-B agonist and alpha-2-delta voltage-gated calcium channel blocker developed in Russia for anxiety, insomnia, and PTSD. It crosses the blood-brain barrier (unlike GABA supplements) and produces potent anxiolytic and social confidence effects. However, it carries significant addiction and withdrawal risks — tolerance develops within days of daily use, and withdrawal can be severe.
What are the side effects of Phenibut?
Common: Drowsiness, dizziness, nausea, tolerance with repeated use. Serious: Physical dependence develops rapidly with daily use. Withdrawal can be severe and dangerous (anxiety, insomnia, psychosis, seizures). Respiratory depression when combined with alcohol or other CNS depressants. Rare: Hallucinations, severe rebound anxiety, suicidal ideation during withdrawal.
How is Phenibut administered?
Phenibut is administered via oral (powder, capsules). take on an empty stomach — food significantly reduces absorption. slow onset (2-4 hours)..
What is the half-life of Phenibut?
The half-life of Phenibut is 5-6 hours.
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