Phenibut: The Soviet-era anxiety drug now fueling a global online supplement controversy

Nature · Published 3 October 2026 Swipe more like this →

In short: Developed in the 1960s as a clinical treatment for anxiety and insomnia, phenibut is a synthetic GABA analogue that crosses the blood-brain barrier. While prescribed in parts of Eastern Europe, it is increasingly sold online as an unregulated supplement in the West, sparking serious concerns over addiction, withdrawal, and overdose.

Synthesized at the A. I. Herzen Leningrad Pedagogical Institute in the Soviet Union, phenibut was introduced for medical use in the 1960s. It functions as a central nervous system depressant, acting as a GABA-B receptor agonist and a gabapentinoid. By substituting a phenyl ring onto the GABA molecule, researchers enabled the compound to penetrate the blood-brain barrier, a feat the original neurotransmitter cannot achieve on its own. Today, it remains a legitimate pharmaceutical in countries like Russia, Ukraine, Belarus, and Latvia, where it is used to treat conditions ranging from vestibular disorders and stuttering to post-traumatic stress disorder.

Outside of these regions, the drug occupies a precarious legal and safety space. In the United States, the FDA has determined that phenibut does not qualify as a dietary ingredient, rendering products marketed as such illegal. Despite this, it remains widely available online. Because of its delayed onset—often taking two to four hours to kick in—recreational users frequently miscalculate their dosage, leading to dangerous consumption patterns. High doses can cause severe symptoms, including delirium, seizures, and acute psychosis, with withdrawal often requiring medical intervention similar to that used for baclofen dependence.

The drug's profile is complex, with its effects varying significantly by dose. While low concentrations may mildly increase dopamine, providing stimulatory benefits, higher doses act as potent depressants. The risks are compounded by the fact that phenibut can potentiate other substances, including alcohol and opioids. As reports of addiction and toxicity rise, several nations, including Australia, France, and Italy, have moved to classify it as a controlled substance. For those seeking it online, the lack of standardized regulation means that servings in supposed supplements can vary wildly, from zero to over 1,100 milligrams, turning self-medication into a high-stakes gamble.

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