Introduction and Aims There has been a global increase in the availability and use of novel psychoactive substances (NPS) over the last decade. Phenibut (β‐phenyl‐γ‐aminobutyric acid) is a GABA B agonist that is used as an NPS. Here, we bring together published scientific and grey information sources to further understand the prevalence of use, desired effects and acute toxicity of phenibut.

Design and Methods Using European Monitoring Centre for Drugs and Drug Addiction Internet snapshot methodology, we undertook an English language Internet snapshot survey in May 2015 to gather information on the availability and price of phenibut from Internet NPS retailers. To gather information on prevalence of use, desired effects and/or adverse effects, we searched grey literature (online drug discussion forums) and medical literature (PubMed and abstracts from selected International Toxicology conferences).

Results We found 48 unrelated Internet suppliers selling phenibut in amounts ranging from 5 g (US$1.60, £1.01/g) to 1000 kg (US$0.23, £0.14/g). Capsules containing 200–500 mg of phenibut were available in packs of between 6 (US$4.45, £2.80/g) and 360 (US$0.43, £0.27/g). According to the grey literature, phenibut is taken for its anxiolytic and euphoric properties, with tolerance and withdrawal syndromes commonly reported adverse effects. Phenibut is taken orally at an average dose of 2.4 g. Case reports in the medical literature feature users who present to emergency departments heavily sedated or experiencing withdrawal. There have been no reported deaths relating to phenibut use.