Phenibut is an anxiolytic drug used in Russia and its bordering countries to treat various neurological and psychiatric disorders. One of its most significant advantages over benzodiazepine tranquilizers is the ability to alleviate anxiety without causing sedation or drowsiness. Besides that, Phenibut has nootropic, antiamnesic and antihypoxic properties.

It is used in the treatment of asthenic (chronic fatigue) and anxiety disorder, insomnia, fears and also as a preoperative anxiolytic.

Phenibut was discovered in the 1960s at the Leningrad Herzen Pedagogical Institute (Soviet Union). In 1975, it was included in astronaut’s medical kit during Apollo-Soyuz test project as a tranquilizer that does not impair working performance. As of today, it is still marketed in CIS countries as an anxiolytic drug, also known as Noofen. In western countries, it is available as OTC anti-anxiety supplement, or you can also buy Phenibut from russian pharmacies.


Mechanism of action

The active ingredient of Phenibut is β-phenyl-γ-aminobutyric acid. By its chemical structure, it is derivative of GABA and β-phenylethylamine (PEA). Both GABA and PEA are neurotransmitters found naturally in the body.

GABA is the main inhibitory neurotransmitter in the body. GABA receptors are the target for many tranquilizers and anticonvulsant drugs.

Oral administration of GABA is not effective because of its inability to cross blood-brain-barrier. The phenyl ring in Phenibut molecule allows it to penetrate BBB significantly better.

PEA is a neuromodulator of catecholaminergic transmission that is present in the brain in tiny quantities. Many phenylethylamine derivatives are psychoactive drugs, mostly psychostimulants.

The primary mechanism of action is GABA-mimetic. Phenibut does increase the release of GABA from presynaptic nerve endings. It acts mainly on GABA-B receptors.

It also has dopaminergic action. An intraperitoneal injection of Phenibut at the dosage of 50 and 100 mg/kg increased the levels of dopamine and its metabolites in rats. The activation of dopaminergic processes may be involved in its pharmacological effects. Antipsychotic medication Haloperidol, which is an antagonist of dopamine receptors, antagonized dopaminergic effects of Phenibut in mice.

Another possible part of the anxiolytic action is antagonism of PEA, which can be viewed as endogenous anxiogen.


Clinical application and indications

Indications for use as suggested by official instructions are:

  • Asthenia (chronic fatigue).
  • Anxiety disorders.
  • Tics and stuttering in children.
  • Insomnia in elderly patients.
  • Alcohol abstinence syndrome.
  • Meniere’s disease and vertigo.


It is mostly used to treat anxiety disorders. The drug also used in Addiction medicine. Phenibut can be used to treat alcohol withdrawals, and, according to studies, in opioid withdrawals too. Chronic administration of Phenibut antagonized the development of morphine dependence in mice, and reduced withdrawal effect.

Phenibut is also popular outside of CIS countries for its huge recreational value.  People often use it to alleviate social anxiety, because Phenibut is particularly effective at this and do not require systemic administration unlike Racetams (e.g Piracetam).  But what is important, is that Phenibut is the substance that can be easily abused. Chronic administration leads to withdrawal syndrome after cessation. To avoid this, it is necessary to take Phenibut responsibly.



Dosage and how to take

The dosages as suggested by the instruction are:

  • For adults – 250-500mg three times a day. The maximum single dose is 750mg, for patients older than 60 years old 500mg. The length of the treatment course is 2-3 weeks.
  • For kids from 8 to 14 years old – 250mg three times a day.


In Russia, it is sold in pharmacies in pill form. It’s just 5 grams per package and the price is pretty high.  Phenibut powder that is sold OTC in the United States is cheap and can be bought in pounds. That is another reason why so many people abuse it.


Side effects and contraindications

Side effects that are listed in the instruction are drowsiness, irritation, anxiety, headache, nausea and allergic reactions. During long-term usage at high dosage, the drug can be hepatotoxic.

Contraindications for use are hypersensitivity to the drug, hepatic insufficiency, pregnancy and lactation. Should be taken with caution by people with erosive gastritis.