Our evidence-based analysis of Phenibut features unique references to scientific papers and anecdotal reports.

What Is Phenibut?

Phenibut is a central nervous system depressant developed in the 1960s in Russia as a treatment for insomnia and anxiety. It is sold by prescription in Russia, Latvia, Kazakhstan, and the Ukraine, where it is used for various conditions ranging from sleep disorders and depression to alcoholism, stuttering, and motion sickness.‍[1]

It is not approved for any medical use in North America or Europe but is widely used off-label as a recreational drug and nootropic.

Phenibut is a controversial supplement. Many people praise it for its ability to reduce anxiety and increase social fluency. Others are skeptical due to the lack of human studies on it, along with its many side effects, the potential for overdose and addiction, and intense withdrawal symptoms make it a dangerous drug.

Phenibut’s legal status varies throughout the world. In the US, it is unregulated and can be legally sold and possessed. It is illegal to sell phenibut in Canada, but it can be legally imported and possessed in amounts not exceeding a 90–day supply. In other nations, regulations on phenibut are complex and varied.

Benefits and Effects of Phenibut

Anti-Anxiety Treatment

Phenibut was created as an anxiety reducer. It is widely used in Russia to treat a range of anxiety-related disorders, including tension and fear, asthenia, depression, post-traumatic stress syndrome, and as a pre- or post-operative medication. It is also used to treat post-traumatic stress, stuttering, and balance disorders.‍[2]

The majority of research on phenibut consists of Russian animal studies, but there is more human research on its anti-anxiety properties than any other aspect of the drug.

In one study trial involving 30 children aged 8 to 16 years old, the daily administration of phenibut for 2 months was shown to diminish occurrences of tension headaches.‍[3]

In a similar study by the same research group, 500 mg of phenibut was given daily to 34 adolescents with ADHD, while their mothers were given a tranquilizer called Adaptol. At the end of the 45-day study, 73.5% of the adolescents showed improvement in anxiety symptoms, while 69.7% of the mothers showed improvement.‍[4]

In a study of 62 adult patients with anxiety-phobic disorders, supplementation with 1000 mg of phenibut daily resulted in improvements in 73% of cases.‍[5]

Many users report that phenibut gives them relief from social anxiety,‍[6] obsessive-compulsive disorder,‍[7] and psychiatric problems.‍[8]

Cognitive Enhancement

Phenibut’s creators describe it as a cognitive enhancer, but research on that effect is minimal.

In one of the few cognition-related human studies, a group of 50 adolescents with ADHD given 500–700 mg of phenibut per day for a month were reported to show improvement in self-control, sustained attention, and acoustic-verbal memory.‍[9]

Animal studies suggest that phenibut enhances cognition by facilitating movements in response to a conditioned stimulus,‍[10] accelerating the development of defensive conditioning,‍[11] and improving interhemispheric transmission in rat brains.‍[12]

Whether or not phenibut has significant nootropic properties is a subject of debate among users, with some saying that it gives them mental clarity and motivation.‍[13] Others report that its sedating effects are so strong that it interferes with mental performance.‍[14]

Insomnia Treatment

In countries where phenibut is prescribed, such as Russia, often used to treat insomnia and sleep disorders.‍[15]

Anecdotal evidence from users on this aspect of phenibut is mixed.  Some users say that it can provide sound, refreshing sleep when taken in relatively low doses.‍[16] Others report that taking phenibut interfered with their ability to fall or stay asleep.‍[17]

How It Works

Phenibut is an analog of the brain chemical gamma-aminobutyric acid or GABA, the primary inhibitory neurotransmitter.

GABA blocks impulses between nerve cells in the brain, playing the opposite role of the excitatory neurotransmitter glutamate.

Though GABA can be taken as a supplement, it cannot cross the blood-brain barrier.

Phenibut is created by adding a phenyl group to the GABA molecule, enabling it to cross the blood-brain barrier and bind to GABA receptors in the brain.

Activating GABA receptors calms neural activity, reducing anxiety and creating a sense of relaxation. This action is believed to be responsible for phenibut’s calmative and anti-anxiety properties.‍[18]‍[19]

Phenibut also stimulates the brain’s receptors for dopamine, the neurotransmitter associated with pleasure, reward, and motivation. This action may be responsible, at least in part, for the mood lifting, decrease of social anxiety, and feelings of euphoria reported by many phenibut users.‍[20]

Phenibut is metabolized in the liver and crosses the blood-brain barrier within 2–4 hours of ingestion. It has a half-life of about 5 hours, and its duration of action can extend from 15–24 hours, depending on the amount ingested.‍[21]‍[22]


The recommended dosage of the branded version of phenibut, Noofen, for anxiety treatment is 250–500 mg, taken 3 times per day.‍[23]

The maximum single dose can be increased to 750 mg for patients under 60 years old.‍[24]

The course of treatment is 2–3 weeks but can be extended to a maximum of 4–6 weeks, if necessary.‍[25]

There is no universally accepted optimal dosage for phenibut taken recreationally or for off-label use. Users report a wide range of dosages.‍[26]‍[27]

It’s worth noting that the usual recommendation to start with the lowest possible effective dosage and adjust as necessary is particularly pertinent to phenibut. It’s a very potent and long-lasting compound, and its effects vary considerably from user to user.

Cases of overdose‍[28] and dependence‍[29] related to high doses have been documented, and higher doses are more likely to trigger unpleasant side effects.

Taking phenibut regularly can lead to dependence and addiction.‍[30]‍[31]


Stacking is the term used when two or more nootropic supplements are taken to derive synergistic benefits through the presence of the other components. This practice has commonly been among nootropic users.

When it comes to phenibut, it is sometimes added to people’s stacks to reduce anxiety on days that are extra stressful.

Stack for Mood and Anxiety

A fairly powerful stacking option to address anxiety, mood control, or sleeplessness is a combination of phenibut, phosphatidylserine, and bacopa monnieri.

As needed (Phenibut not recommended for daily use)

Stack for Athletic Recovery

Today, extreme athleticism seems to be the lifestyle of many weekend warriors.

Athletes seeking an additional edge or extra help with hard training may consider a recovery stack.

Phenibut, combined with L-theanine and centrophenoxine, could help reduce body soreness, help to motivate to a new strength or endurance level, and result in enhanced muscular development.

As needed (Phenibut not recommended for daily use)

Side Effects

Side effects associated with phenibut range from headaches, excessive sleepiness, hangover-like effects, dizziness, nausea, poor balance, fatigue, and feelings of electric shocks in the arms and legs.

When taken in large doses, phenibut can cause trouble breathing and unconsciousness.‍[32]

Phenibut users also report additional side effects related to high doses, including vivid nightmares, night sweats, sleep paralysis, and night terrors;‍[33] severe depression;‍[34] and sexual/erectile dysfunction.‍[35]‍[36]

According to user self-reports, withdrawal symptoms including anxiety, insomnia, and depression are very common and may be experienced even after taking phenibut for a short time.‍[37]

There is no documented listing of substances with which phenibut is known to interact. Still, it may dangerously potentiate other compounds that affect GABA or depress respiration, including benzodiazepines, antidepressants, opioids (such as oxycodone and hydrocodone), or alcohol.‍[38]

Where to Buy

Phenibut can be purchased online in bulk powder form from specialty vendors. We recommend AbsorbYourHealth.com as a trusted source for ordering phenibut or any other nootropics that you may be looking for.

Closing Thoughts

For many people, phenibut relieves crippling anxiety and restores them to normal life. Others condemn it as a dangerous and potentially addictive pharmaceutical that’s easy to abuse.

Phenibut has been used in Russia as a reportedly successful medical treatment for more than 50 years, but taking a prescription drug under the supervision and monitoring of a physician differs from self-medicating.

There isn’t much available research on how phenibut affects humans, but studies indicate that it can be a medically sound treatment for anxiety-related disorders.

As phenibut use becomes more common, more is being learned about its many side effects, withdrawal symptoms, and alarming potential for dependence and addiction.

Does phenibut have significant nootropic properties? Possibly, but there isn’t enough research on how it affects human cognition, to say for sure.


Planning to start a new supplementation regimen? See our medical disclaimer.

This page was last updated on July 16, 2021.