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What is Phenibut?

Sold under the brand names Anvifen, Fenibut, and Noon amount others, is a central nervous system depressant with anxiolytic effects, and is used to treat anxiety, insomnia, and for a variety of other indications. It is usually taken by mouth as a tablet, but may be given intravenously.

Side effects of Phenibut include:

sedation, sleepiness, nausea, irritability, agitation, dizziness, and headache among others. Overdose of phenibut can produce marked central nervous system depression including unconsciousness. 

The medication is structurally related to the neurotransmitter y-aminobutyric acid (GABA), and hence is a GABA analogue. Phenibut is thought to act as a GABA receptor agonist, similarly to baclofen and y-hydroxybutyrate (GHB). However, at low concentrations, phenibut mildly increases the concentration of dopamine in the brain, providing stimulatory effects in addition to the anxiolysis.

Phenibut was developed in the Soviet Union and was introduced for medical use in the 1960s.Today, it is marketed for medical use in Russia, Ukraine, Belarus, Kazakhstan, and Latvia. The medication is not approved for clinical use in the United States and most of Europe, but it is also sold on the Internet as a supplement and purported nootropic.  {henibut has been used recreationally and can produce euphoria as well as addiction, dependence, and withdrawal. 


Intolerance to phenibut

  • Pregnancy and breastfeeding

  • Children who are younger than two years of age

  • Liver insufficiency or failure

  • Ulcerative lesions of the gastrointestinal tract

Phenibut should not be combined with alcohol.​

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