Phenibut is a central nervous system depressant that was originally developed in the Soviet Union in the 1960s. It is a derivative of the neurotransmitter gamma-aminobutyric acid (GABA) and is used in some countries for its anxiolytic (anxiety-reducing) and nootropic (cognitive-enhancing) effects.

Phenibut is often used to reduce anxiety, improve sleep, and enhance cognitive function, but it is not without risks. It can cause side effects such as dizziness, nausea, and sedation. Additionally, there is potential for dependence and withdrawal symptoms with regular use, and it can interact with other medications and substances.r medications and substances.