Pharmacopsychiatry 2020; 53(05): 201-208
DOI: 10.1055/a-1151-5017

Safety and Tolerability of the Anxiolytic and Nootropic Drug Phenibut: A Systematic Review of Clinical Trials and Case Reports

1   Latvian Institute of Organic Synthesis, Riga, Latvia
2   Department of Neurology and Neurosurgery, Riga Stradins University, Riga, Latvia
Jelena Vrublevska
3   Department of Psychiatry and Narcology, Riga Stradins University, Riga, Latvia
Baiba Zvejniece
1   Latvian Institute of Organic Synthesis, Riga, Latvia
Edijs Vavers
1   Latvian Institute of Organic Synthesis, Riga, Latvia
Gundega Stelfa
1   Latvian Institute of Organic Synthesis, Riga, Latvia
4   Latvia University of Life Sciences and Technologies, Jelgava, Latvia
Liga Zvejniece
1   Latvian Institute of Organic Synthesis, Riga, Latvia
Maija Dambrova
1   Latvian Institute of Organic Synthesis, Riga, Latvia
5   Department of Pharmaceutical Chemistry, Riga Stradins University, Riga, Latvia
› Author Affiliations
Funding: This study was supported by the framework of the EU-ERA-NET NEURON project TRAINS.


Phenibut is a nootropic drug that exerts anxiolytic and antinociceptive effects by acting on the GABAB receptor and the α2-δ subunit of voltage-dependent calcium channels. An increased number of reports of dependence to and intoxication by phenibut purchased online on the one hand and the wide prescription of phenibut in Eastern Europe for more than half a century on the other hand have resulted in a number of controversies regarding its use. In this review, we have summarized currently available information from case reports of phenibut dependence and intoxication and safety data from clinical trials. We included 14 dependence and intoxication case reports (16 patients) and reviewed 11 phenibut clinical trials (583 patients). The clinical symptoms in the case reports included cardiovascular effects, insomnia, anxiety and agitation, hallucinations, and depressed level of consciousness. In addition, the doses used (0.5–100 g/day) were much higher than the recommended daily dose (0.25–2 g/day). An analysis of phenibut side effects described in the clinical trials showed adverse events in only 5.66% of patients, and the most reported side effect was somnolence (1.89%). There are discrepancies in the reported side effects of phenibut in clinical trials compared to those reported in cases of online-purchased phenibut dependence and intoxication. The current systematic review provides evidence that, at therapeutic doses, phenibut is safe and well tolerated with minor adverse effects, but questions regarding the quality of phenibut obtained online and the contribution of alcohol and other drug abuse to phenibut dependence and intoxication remain open.

Publication History

Received: 28 September 2019
Received: 14 March 2020

Accepted: 26 March 2020

Article published online:
27 April 2020

© 2020. Thieme. All rights reserved.

© Georg Thieme Verlag KG
Stuttgart · New York

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