Phenibut: Review of Nootropic Benefits, Dosage, & Side Effects

Updated on February 28, 2023
 by — reviewed by Jason Williams, PhD (Contributor: George Collins / Editor: Yoko Hill)

This review will examine Phenibut's nootropic features, benefits, and side effects. We will also discuss the appropriate dosage and how Phenibut can be used to improve cognitive function.

Originally made for the Russian space program, Phenibut was designed to help astronauts cope with the stresses of space travel. Phenibut was subsequently made available as a dietary supplement and has become a popular choice for those seeking to improve their cognitive function, relieve anxiety and stress.

Phenibut is structurally similar to the neurotransmitter GABA and acts as a GABAergic compound. This means that it inhibits the release of GABA, increasing the level of dopamine and norepinephrine in the brain.

Let's look closely at Phenibut's nootropic effects and see what the research says.

Phenibut Review Summary

Phenibut (β-Phenyl-GABA or β-Phenyl-γ-aminobutyric acid) is a nootropic supplement with cognitive-enhancing and anti-anxiety effects. It works by modulating levels of the neurotransmitter GABA. Phenibut is structurally similar to GABA and acts as a GABAergic compound.

Phenibut is generally well-tolerated, but side effects can include drowsiness and withdrawal symptoms.


  • Has anti-anxiety and cognition-enhancing effects
  • Helps improve sleep quality
  • Improves symptoms of depression
  • Produces a sense of well-being
  • Great for social anxiety


  • Not suitable for long-term use

What Is Phenibut?

phenibut structure

Phenibut (also known as β-Phenyl-GABA, β-phenyl-γ-aminobutyric acid, Noofen, Anvifen, Fenibut and Citrocard) is a GABA analog that can cross the blood-brain barrier (BBB) (1).

Professor Vsevolod Perekalin's team at the A. I. Herzen Leningrad Pedagogical Institute (USSR) synthesized Phenibut, which was introduced into clinical use in Russia in the 1960s. It is structurally similar to the neurotransmitter GABA (γ-aminobutyric acid) and acts as a GABAergic compound.

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GABA also maintains a proper balance of glutamate, the primary excitatory neurotransmitter. Glutamate may induce a seizure if there is too much of it, and insufficient GABA can lead to coma.

A healthy brain maintains a critical equilibrium between GABA and glutamate. Thus, GABA acts like a "brake" on neuronal circuits during stress, as it limits the activity of some neurons.

Anxiety and stress can all be improved by boosting GABA levels in the brain. Clinical studies have shown that a supplement like Phenibut can help increase GABA production and improve alpha brain wave activity (2).

How Does Phenibut Work In The Brain?

Phenibut's psychopharmacological activity is most similar to baclofen, a p-Cl-derivative of phenibut. It acts primarily as a GABA-mimetic at GABA(B) receptors and also has some effect on GABA(A) receptors (3).

In addition, Phenibut stimulates dopamine receptors while competing with beta-phenethylamine (PEA) for binding sites - PEA being a suspected endogenous anxiogenic. It also has a phenyl ring.

phenibut review

Incorporating a phenyl ring into the GABA molecule increases its ability to cross the BBB by binding to specific receptors. This allows Phenibut to act as a nootropic and anxiolytic agent.

Let's take a closer look at each of these mechanisms in turn.

GABA-mimetic Action

Its GABA-mimetic action is thought to underlie Phenibut's anxiolytic and nootropic effects.

Phenibut activates GABA-B receptors, which are found in both the central nervous system (CNS) and peripheral nervous system (PNS). The activation of these receptors inhibits the release of several neurotransmitters, including dopamine, noradrenaline (norepinephrine), and serotonin.

Phenibut also has a GABAergic effect on the brain by inhibiting the release of excitatory neurotransmitters. This increases feelings of relaxation and tranquility.

Activation of Dopamine Metabolism

Phenibut also stimulates dopamine receptors while competing with beta-phenethylamine (PEA) for binding sites. Dopamine is an important neurotransmitter involved in motivation, attention, and learning.

It plays a role in the brain's reward s system by reinforcing behaviors that are essential for survival, such as eating and mating. Phenibut's ability to increase dopamine levels may explain its mood-boosting effects and why it is sometimes used as a treatment for people with depression.

Antagonism of b-phenethylamine (PEA)

Phenethylamine is an organic compound that acts as a central nervous system stimulant in humans. It is also classified as a natural monoamine alkaloid and trace amine, producing it endogenously in small quantities in the brain.

Phenethylamine is thought to play a role in regulating mood and energy levels. It is also involved in the release of dopamine and other neurotransmitters. Phenibut has been shown to antagonize (4) the effects of phenethylamine, which may account for its ability to reduce anxiety and improve mood.

Anxiolytic Activity

Because Phenibut works on the GABA system in the brain, it has anxiolytic effects.

In 2009, one animal study showed how Phenibut affected neuronal activity and interaction in the hippocampus (part of the brain) during emotionally distressing situations. The research found that, when taking Phenibut, there were more common inputs to recorded neurons and fewer excitatory connections (5). This means that Phenibut increases inhibitory (calming) activity in the brain and reduces excitatory (stimulating) activity.

Thus, Phenibut decreased behavioral reactivity and anxiety by affecting the activity level of the hippocampus and neocortex, neuronal synchronization, and excitation spread among neurons. 

What Is Phenibut Used For?

Phenibut has a wide range of potential applications due to its unique pharmacological profile. It is most commonly used as a tranquilizer, anxiolytic, and nootropic drug. Phenibut treats anxiety, stress, and depression.

In Russia, Phenibut treats anxiety, fear, sleeplessness (insomnia), tension, stress, tiredness, post-traumatic stress disorder (PTSD), depression, alcoholism, and arrhythmia.

Most of the studies done on Phenibut have been done on animals. However, there have been a few human studies conducted as well. That said, we have data on how GABAergic and dopaminergic drugs affect humans, so we can extrapolate from that data below.

How GABA Increases Human Growth Hormone (HGH)

Phenibut, or even GABA, is used by bodybuilders and athletes to aid in the recovery and growth of muscle tissue. There are several studies that demonstrate that taking GABA raises Human Growth Hormone.

19 subjects were given 5 grams of GABA oral, while 18 received a placebo. 3 hours post-dose, researchers took blood samples from all participants. The researchers found that GABA increased plasma growth hormone levels significantly (6).

How GABA Reduces Insomnia

A randomized, double-blind, placebo-controlled study was conducted by researchers in Los Angeles on 18 patients with sleep problems (7).They were given a placebo or Gabadone (a combination of GABA and 5-hydroxytryptophan).

The Gabadone group fell asleep faster and stayed asleep longer than the placebo group, resulting in a better quality of sleep overall. When Phenibut is taken, Biohackers frequently report a similar improvement in sleep quality.

What Are The Benefits Of Phenibut For Cognition?

Phenibut is a GABA analog. Because Phenibut has a phenyl ring and can pass the blood-brain barrier (BBB) more readily than GABA taken as a supplement, it can do much more effectively.

We require sufficient levels of GABA in our brain since it is an inhibitory neurotransmitter. When we increase GABA levels with Phenibut supplementation, we assist to keep glutamate in check. Glutamate is an excitatory neurotransmitter; too much of it will lead to anxiety, restlessness, and sleeplessness.

Thus, Phenibut is beneficial for:

  • Reducing stress and anxiety
  • Improving sleep quality
  • Enhancing cognitive performance and focus
  • Aiding in muscle recovery
  • Boosting HGH levels

Where To Buy Phenibut Online?

The quality of a drug goes a long way in determining its potency and safety. It's even more so when the drug in question is unregulated. For a reliable seller that consistently delivers quality batches of Phenibut, we recommend sells Phenibut HCL in powder form. A 50-gram bottle costs $24.99, and they ship worldwide. What we like about is that all of their products are lab-tested for purity and potency.

What Do People Say About Phenibut On Reddit?

Let's take a look at some Phenibut reviews from real people on Reddit.

According to rosamundi1975:

"…For me, 1500 is indeed a high dose and the most I've ever taken. I had nightmares for 2 nights after and severe anxiety. That being said, before I came off of it, I was feeling mighty fine! 500 to 750 is perfect for an avg sized woman"

According to u/doncheadle13

"… I've been using Phenibut for awhile now and it really makes me realize how cynical I can be sometimes. Phenibut can really get you back on track if you ever lose your way. sometimes I really do lose a little bit of motivation in life, a little bit of phenibut can remind you what's good in life, how simple life can be, and how much fun you really can have..."

According to u/Sidney_Kowalski

"Phenibut is the most magical substance I've ever encountered. It's not for everyone, however, because it can be quite addictive both physically and mentally… I've been using it for 4 years now, on and off. I'm currently taking a 2-3 week break because I noticed my tolerance was getting a bit too high, and the effects weren't as strong as they used to be."

Phenibut seems to be quite popular on Reddit, with many users sharing their positive experiences with the nootropic. Some users caution against potential addiction and emphasize the importance of properly cycling Phenibut.

How Do You Take Phenibut For Cognitive Enhancement?

Phenibut is most commonly taken in powder form, either dissolved in water or mixed with another beverage. Phenibut is taken 1 or 2 times daily, once or twice weekly, to avoid developing tolerance.

Phenibut can be taken with or without food. If you experience an upset stomach, it is recommended to take Phenibut with food. Many people find that taking Phenibut in the morning is most effective for anxiety and stress relief while taking it in the evening is best for improved sleep quality.

It's important to note that it can take several hours (sometimes up to 4 hours) for Phenibut to take effect. For this reason, taking Phenibut early in the day is best to assess your tolerance and avoid taking too much.

The recommended dosage of Phenibut varies depending on the desired effect. A 200-500 mg dosage for anxiety relief is typically taken 1-2 times daily. Experienced Phenibut users recommend taking 1 – 1 ½ grams per dose up to 3 times a week.

To prevent tolerance from developing, it's best to take Phenibut less frequently. It is advised to take Phenibut only once or twice a week, with each dose separated by at least 2 days. Phenibut can be addictive and cause withdrawal symptoms, so it's important to be aware of the risks before taking it.

If you're new to Phenibut, start with a lower dose of 200 mg and increase gradually as needed. It's always best to err on the side of caution when taking any new supplement or drug.

What Are The Side Effects Of Phenibut?

While Phenibut is considered safe when taken as directed, bodybuilders who consume much higher doses have reported having mild flushing, tingling, a heightened heart rate and blood pressure, and anxiety.

You can also develop a tolerance to Phenibut rather quickly. If you have an addictive personality, it's best to avoid using this nootropic altogether.

Cycling is cited by many biohackers as the optimal way to consume Phenibut. This entails following the directions for dosages of 2 and 4 days, followed by a few days off. Others suggest using Phenibut only once per week.

Be prepared to do some trial-and-error at first if you want to try Phenibut, but be cautious of withdrawal symptoms; they can be severe if you take too much. Phenibut should not be combined with alcohol or benzodiazepines, as this could lead to coma. GABA-increasing substances should also be avoided.

What Nootropics Are Similar To Phenibut?

Phenibut is similar to other nootropics that increase levels of GABA in the brain, such as L-theanine, 5-HTP, and Melatonin.

  • L-theanine (N-ethyl-L-glutamine) is an amino acid found in green tea that increases levels of GABA and dopamine in the brain (8). It helps to promote relaxation without causing drowsiness.
  • 5-HTP (5-Hydroxytryptophan) is a naturally-occurring amino acid and precursor to serotonin, a neurotransmitter that plays a role in mood, sleep, and anxiety. 5-HTP is commonly used to treat conditions like depression and insomnia (9).
  • Melatonin is a hormone that is involved in the sleep-wake cycle. It is often used as a natural remedy for insomnia and jet lag. Melatonin has been shown to modulate GABA receptor activity (10), thus having a calming effect on the nervous system.

The biggest difference between Phenibut, L-theanine, 5-HTP, and Melatonin, is that Phenibut is more potent and has a greater ability to cross the blood-brain barrier (BBB). This makes it more effective at modulating GABA levels but also more likely to cause side effects such as withdrawals.

What Brain Supplements Can Phenibut Be Stacked With?

Stacking means combining two or more nootropic supplements to amplify each effect. By stacking Phenibut with the right dietary supplements or products, you can get even better results from using the drug.

For those extra stressful days, you can amplify Phenibut's effect and improve sleep by stacking it with Phosphatidylserine and Bacopa Monnieri.

The recommended stack dose for this combination is 100 mg Phosphatidylserine, 300 mg Bacopa Monnieri, and 250 mg Phenibut. But remember not to use it for several days in a row as it can lead to an increased risk of tolerance and Phenibut addiction.

If you want that extra boost during your workouts and quick recovery afterward, combining Phenibut with L-theanine and Centrophenoxine makes for a great recovery stack. It will boost your endurance, reduce body soreness, and increase your energy levels, enabling you to work out longer and harder.

The recommended dose for this stack is 200 mg L-Theanine, 250 mg Phenibut, and 250 mg Centrophenoxine.

If you're looking for the ultimate Phenibut stack, we recommend looking into nootropic blends like NooCube. NooCube contains a powerful combination of 13 nootropics, including Alpha GPC, Huperzine A, Bacopa Monnieri, and much more.

This blend of nootropics will help to boost your cognitive function, increase mental clarity, and improve focus and concentration. It's the perfect foundation to stack with Phenibut for a greater cognitive boost.

NooCube is available in capsule form right here:

Frequently Asked Questions (FAQ)

Let's take a look at some of the most frequently asked questions about Phenibut.

How Long Does It Take for Phenibut to Work?

When taken in capsule form or as a powder combined with water, it takes around 2 hours for Phenibut to take effect. Phenibut can take up to 4 hours on a full stomach to kick in.

How Does Phenibut Make You Feel?

Phenibut creates feelings of relaxation, euphoria, and calmness. It has been described as a "euphoric sedative." Phenibut will make you more social and talkative and can reduce inhibitions. An overall sense of well-being is common.

What’s the Half-Life of Phenibut?

The half-life of Phenibut is 5 hours. Half-life refers to the amount of time it takes for 50% of a drug's active ingredient to be metabolized in the body after ingestion. This means that, approximately 5 hours after the first Phenibut dose, the concentration in the body has been reduced by half.

Is It Safe to Use Phenibut?

Phenibut is considered safe when used in moderation and according to the directions on the label. However, because Phenibut can cause dependence and tolerance, it's important to take a break from using it every few days.

Can I Overdose on Phenibut?

Yes, it is possible to overdose on Phenibut. Phenibut is a central nervous system depressant and can cause slowed or slurred speech, drowsiness, impaired coordination, and vomiting. In high doses, it can cause seizures, coma, and death. If you think you or someone else may have overdosed on Phenibut, call 911 or your local poison control center immediately.

How to Make Phenibut Work Faster?

You can speed up the onset by taking it on an empty stomach first thing in the morning. If you use it sublingually, it'll work even faster. Using it alongside Caffeine will also make it work more quickly.

Is Phenibut Fda-Approved?

Phenibut is a psychoactive drug produced in Russia to treat anxiety and sleep problems. However, it has not received FDA approval for any use.

Is Phenibut Legal?

Phenibut is currently unclassified in the United States. This means that it is technically legal to buy, possess, and use. However, because Phenibut is structurally similar to a banned compound called baclofen, it is possible that the drug could be classified as a controlled substance in the future. Phenibut is considered a controlled substance in Australia, France, Hungary, Italy, and Lithuania.


So what do we think about Phenibut?

Overall, we think it's a great nootropic with potent anxiolytic effects. It's especially useful for reducing stress and can help you to feel more relaxed and sociable. Phenibut is also a great cognitive enhancer, promoting focus, concentration, and mental clarity.

However, Phenibut can cause dependence and tolerance, so taking a break from using it every few days is important. And, as with all nootropics, start with a lower dose to assess your tolerance.

If you want to get your hands on some Phenibut, you can find it right here:

Phenibut: Review of Nootropic Benefits, Dosage, & Side Effects 1

Do you consider buying Phenibut? Our review reveals if it’s worth the risk, what dosage is safe and where to buy third-party tested pure Phenibut powder.

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