What is Phenibut Phenibut is not as known nor does it have as widespread use as other nootropics such as piracetam, Alpha GPC, caffeine, or L-theanine. However, phenibut has demonstrated numerous benefits over tens of decades through both formal studies and anecdotal documentation. Phenibut is a nootropic supplement designed to simulate the naturally occurring inhibitory neurotransmitter γ-aminobutyric acid (GABA) that …