A derivative of the naturally occurring inhibitory neurotransmitter gamma-aminobutyric acid (GABA) called phenibut is increasingly detected in dietary supplements marketed online. It is marketed as mood enhancer, for relaxation and assisting sleep, as exercise recovery aid for bodybuilders, as cognitive enhancer or ‘smart drug’, and for boosting sexual performance. Phenibut is not licensed as a medicine in European Union, the United States (US) or Australia, and was first detected in a 2011 seizure in Sweden. In the past two years, public health concerns have been raised around its presence in potentially harmful dietary supplements in France, Sweden, the US and Australia. Search engines have also recorded an increased trend in online interest into the purchasing of and information seeking around products containing phenibut. This short communication provides a comprehensive narrative review of extant literature currently available on this GABA derivative in relation to its legitimate clinical use, availability and use by the public, its effects, and clinical care of toxicity and dependence. It concludes with key recommendations for surveillance and regulation, public health, harm reduction, clinical care and health professional training.