Phenibut is a GABA-acting psychotropic drug with anti-anxiety and nootropic effects. In Russia, it’s used for PTSD, anxiety, fatigue, insomnia, depression, and alcoholism. In the US, phenibut is classified as a supplement. But it’s also used recreationally and can cause addiction. Read more below to learn about its effects, side effects, and natural alternatives.

Disclaimer: By writing this post, we are not recommending this drug. Some of our readers requested that we commission a post on it, and we are simply providing information that is available in the scientific and clinical literature. Please discuss your medications with your doctor.

We also included a section about natural alternatives, as there are a variety of safe and natural ways to boost GABA and achieve similar effects without the health risks.

What is Phenibut?

Phenibut (beta-phenyl-GABA) is a synthetic drug similar to the calming neurotransmitter GABA. It boosts GABA activity in the brain and stimulates dopamine and serotonin neurotransmission [1, 2, 3].

By boosting GABA, serotonin, and dopamine – three crucial neurotransmitters in the brain – this drug can have profound effects on cognition, mood, and energy levels [2].

Phenibut was developed in Russia in the 1960s and has since been clinically used to relieve tension, fear, anxiety, posttraumatic stress disorder, depression, and insomnia. It’s also used to enhance intellectual function in various mental disorders. All of these approved uses are limited to Russia [4].

It’s often used recreationally to ease social anxiety and induce euphoria, which earned it the nickname “the happy drug” across online forums. Many people self-medicate with phenibut to ease fear and anxiety, boost cognition and positive feelings, and even to enhance physical endurance and libido. Students and entrepreneurs use it as a nootropic and call it “the smart pill”.

Is Phenibut Legal?

Phenibut is technically legal but it is not approved by the FDA for clinical use In the United States.

It’s classified and sold as a nutritional supplement. But it is not “nutritional” but a synthetic designer drug that can cause side effects, dependency, withdrawal, and overdose. Its sale and use remain an unregulated, grey area. It is sold online under various brand names, such as Noofen, Anvifen, and Fenibut [5].

Citrocard is a very similar analog of Phenibut (phenibut citrate), although not identical [6].

Phenibut Dosage and Duration of Effect

A “Phenibut Warning” was officially issued in 2013 following near-fatal overdoses in upstate New York. It mentions the availability of phenibut HCL, a cheap, white, sour-tasting powder soluble in water or alcohol. According to this report, people typically take 0.5 – 4 g, it begins to act in 60 – 90 minutes, and lasts for 4 – 10 hours.

The actual dosage in most clinical studies varied between 500mg – 1g/day.

What Makes Phenibut Psychoactive?

By chemically modifying GABA (adding a phenyl ring), Russian scientists made Phenibut as a drug that can easily penetrate the blood-brain barrier [2].

Phenibut achieves its psychoactive effects by [5]:

  • Activating both known GABA receptors (GABA-A and GABA-B) [7].
  • Increasing dopamine and serotonin
  • Blocking an anxiety-provoking brain substance called beta-phenylethylamine (PEA)

Just like Dexedrine is the most active component of Adderall, so is R-phenibut the active component in Phenibut. R-phenibut was two times stronger GABA booster and painkiller than the other component (S-phenibut) in animal studies [8].

The Russian Cosmonauts Story

There’s a popular story that gives Phenibut the attributes of a “Russian wonder drug”. We can’t speak to the validity of this story, though, so it remains more of a legend that gained a lot of attention and changing interpretations over time.

According to it, phenibut was used in the Russian space program when US-Russian joint space mission ran into technical problems in the 1970s. The mission ran into problems and couldn’t find any means to fix a docking mechanism of the spacecraft. The only last resort solution was to tell the Russian astronauts to take phenibut and rest. And apparently, the combined powers of rest and phenibut brought calm and peace to the astronauts, enabling them to come up with a creative solution to the whole fiasco.

The downside of this story is that it romanticizes phenibut use without any solid scientific evidence or mentions of side effects. People take it to give validation to their own recreational use of this drug. The actual scientific literature has a different story to tell.

Phenibut Effects

Indeed, there are over 300 published scientific studies about Phenibut. But most of them are in Russian and were conducted on animals or in cells. And some readers may be disappointed to know that evidence is lacking to support a large part of the inflated online claims [2].

Phenibut may have therapeutic value for some conditions, but more clinical research is needed.

The main flaw in interpreting the available evidence is thinking that phenibut and GABA are the same. This drug was designed precisely to be stronger than the naturally-occurring GABA and to cross the blood-brain barrier. Its effects are more similar to the drugs baclofen, diazepam, and piracetam [2].

One of the main drawbacks is that people easily build tolerance and become dependant on it. This can cause addiction, withdrawal, or even overdose. Withdrawal can be quite severe, highly unpleasant, and hard to overcome [9].

1) Protecting the Brain

Phenibut reduced amnesia and brain damage in rats with stroke. It improved poor brain blood flow, sensory and movement deficits, aiding in recovery. Phenibut increased BDNF, crucial for neurogenesis, the process of making new brain cells. It also turned on genes that make new blood vessels in the brain and improve circulation (VEGF) [10, 11].

It improves memory in rats with amnesia and protected the brain from the damaging effects of electroshocks. Compared to other similar drugs like baclofen, phenibut had the strongest neuroprotective effect [12].

It protected the brain and improved rehabilitation in another study on rats with stroke, but was only effective in animals with an active immune system. It didn’t offer many benefits to rats with a suppressed immune system and stoke [13].

The brain-protective effects are probably a result of enhancing GABA, according to a study on rat brain cells [14].

2) Cognitive Enhancement

Phenibut is a nootropic – a strong cognitive enhancer that increases motivation, memory, attention, and concentration.

In a clinical trial of 62 people with chronic anxiety, phobia, and cognitive impairment, phenibut (1,000 mg/day) improved attention, memory, and emotional intelligence in 73% of the cases [15].

Phenibut improved memory and helped rats learn quicker and adapt to stress in the early stages. Its effects were stable and noticeable very early on. The benefits are probably due to both GABA activation (both GABA-A and GABA-B). The learning and memory enhancement effects were confirmed in another mice study [7, 12].

Interestingly, mice given phenibut over the long term built a tolerance to its sedative action while its nootropic effect was enhanced [2].

In rabbits, phenibut improved learning in rabbits by enhancing the brain’s response to stress. It acted both as a stimulant and as a relaxant [16].

3) Reducing Anxiety and Aggression

Phenibut reduced anxiety in 79% of the cases in a clinical trial of 62 people with anxiety and chronically reduced brain blood flow. At the same time, phenibut reduced fatigue, improved sleep, and energy levels [17].

In a trial of 62 people with anxiety-phobic disorders, phenibut reduced anxiety and improved emotional intelligence. It was effective in people who struggled with anxiety and phobia for 1 – 5 years [15].

The boost in emotional intelligence may explain why people with social anxiety self-medicate with it. People with higher emotional intelligence are better at handling interpersonal relationships, controlling and expressing their emotions.

In rabbits, phenibut reduced fear and anxiety in response to negative emotional stimuli. It helped them escape from stressful situations easier. It had the strongest effect on active rabbits, while it didn’t affect normal or more passive rabbits much [18].

In another animal study, phenibut altered brain waves to boost synchronization, which was linked to reduced anxiety. It also reduced overactivation of the hippocampus and brain cortex to negative emotions, which is especially important for the exaggerated fear response in anxiety. In another animal study, it had similar anti-anxiety effects as Valium (diazepam) [19, 2].

Phenibut decreased aggression and improved social skills in animals in fearful circumstances. It reduced both defensive and competitive aggression. Citrocard, very similar to phenibut, had an even stronger effect [6].

4) Combating Chronic Fatigue Syndrome

Phenibut reduced fatigue by 30 – 50% in most cases in a clinical trial of 53 people with chronic fatigue and poor brain blood flow. It improved both mental fatigue and motivation. In fact, reduced mental fatigue was directly tied to an increase in cognitive function [20].

In a study of 60 children with emotional fatigue (neurasthenia) and anxiety, phenibut (500 mg/day) improved emotional symptoms in 67% of the cases. A similar Russian drug called Adaptol had a stronger effect, though. Phenibut worked better in children who also experienced fatigue, weakness, and pain alongside other emotional symptoms with an 87% improvement [21].

5) Tension Headaches

In a trial of 30 children and adolescents, phenibut reduced the frequency, duration, and intensity of tension headaches over 2 months. It also improved everyday functioning, productivity, sleep, and anxiety – all of which are important for combating headaches. The effects were noticeable after 1 month (dose: 5 – 20 mg/kg/day) [22].

6) Reducing Dizziness

About half of people with high blood pressure also experience anxiety, and dizziness as a result of increased anxiety. In a clinical trial of 58 people, phenibut (500 mg/day) reduced the dizziness, anxiety, and lack of energy after about 2 months [23].

7) Tics and Stuttering

In 30 children with tics and stuttering, phenibut reduced tics in 80% and stuttering in 67% of the cases [24].


Since phenibut improves attention, it may also help with ADHD symptoms. In one clinical trial of 50 children with ADHD, it improved cognition, self-control, sustained, attention, and memory after 1 month (500 – 700 mg/day) [25].

One month is a short time for evaluating ADHD effects; long-term studies need to determine if the beneficial effect can be sustained.

9) Overcoming Addictions

In one trial of 24 people with heroin addiction, phenibut improved mood, memory, attention, and overall cognitive function without increasing the desire for heroin. It didn’t actually reduce drug craving, though [26].

Reports of people using phenibut for opioid withdrawal are increasing. It may act by relieving anxiety, insomnia, fatigue, and cognitive symptoms during withdrawal. Only baclofen, which is similar to phenibut, helped reduce symptoms of opioid withdrawal. Phenibut use for opioid addiction and withdrawal remains largely unproven [2].

What’s even trickier is that phenibut itself can be addictive, cause withdrawal, and interact with other drugs used for opioid dependence [27].

10) Protecting the Heart from Stress

In animals, phenibut protected the heart from stress and improved its pumping capacity. It indirectly increased nitric oxide, which relaxes blood vessels [28, 29].

Phenibut improved blood flow and cleared clogged arteries after stroke in rats (alone or In combination with nicotinic acid) [30].

Both Phenibut and Citrocard protected the heart from alcohol injury in animals. By boosting GABA, improving blood flow, and reducing stress, phenibut also reduced arrhythmias in animal studies [31, 32].

In pregnant rats with high blood pressure, phenibut prevented increases in blood pressure, reduced excessive blood clotting, and blood vessel clogging. It also reduced swelling and oxidative stress, increased blood flow to the uterus, and protected the blood vessels [33, 34].

Safe use of Phenibut in pregnancy has not been established in any clinical studies.

11) Alcohol Dependence

According to one review, phenibut helps reduce the symptoms of alcohol withdrawal. This is based on some Russian experiments and clinical use, but no larger studies exist [2].

In one clinical trial of 22 people, phenibut improved sleep in alcoholics after the initial withdrawal period [35].

Phenibut reduced alcoholic behavior and craving in animals with chronic alcoholism [36].

In animals, Citrocard (phenibut citrate) also prevented from heart damage caused by chronic alcohol intake [37].

12) Balancing the Immune System

Phenibut reduced immune system over-activation in animals. It also restored the number of microbe-engulfing phagocytic cells, which help fight bacteria [38].

On the other hand, phenibut boosted the immune response in mice with suppressed immune systems. It can act directly on white blood cells [39].

Phenibut improved immunity and behavior in mice given an immune-suppressing drug. It can boost immunity by affecting the brain, having a “psycho-immune” effect [40].

13) Breathing Problems

Phenibut prevented apnea and restored normal breathing in rats with very high serotonin. Too much serotonin creates an imbalance in GABA in the brain, which this drug can restore [41].

It also normalized breathing in rabbits exposed to negative emotional stimuli [42].

Phenibut probably reduces breathing problems in stressful situations by boosting GABA in the brain and reducing anxiety.

14) Increasing Heat Resistance

People who work in extreme environments can experience health problems and difficulty adapting. Phenibut may help reduce exertion from physical labor in extreme heat. In one trial, it increased heat resistance combined with another drug (Obsidan), protecting the body from high temperatures [43].

In people under intense physical exertion, a single dose of phenibut (250 mg) prevented overheating, increased tolerance to heat, improved oxygen supply, and helped maintain high working capacity [44].

15) Alleviating Chronic Pain

GABA doesn’t only calm the brain but also helps reduce pain. Phenibut reduced nerve pain in mice by boosting GABA. It also helped with chronic neuropathic pain and inflammation in mice [45, 46, 47].

Phenibut also reduced the emotional response to pain in mice. The emotional, psychological aspect of pain can be even harder to treat than the physical sensation. It’s also often linked to depression and anxiety, which this drug is additionally used for [2+, 48].

No clinical studies have been carried out, but the downside of phenibut is that people can quickly develop tolerance to it. This would probably hold true if using for chronic pain in the long term.

16) Relieving Insomnia

Phenibut is used to treat insomnia in Russia, but the available studies are limited. Phenibut improved sleep in clinical trials of people who suffer from insomnia as a result of various other disorders.

For example, in 12 alcoholics in early abstinence, phenibut increased the duration of key sleep phases over 2 days. It also improved sleep in people with anxiety and headaches [35, 17, 22].

Download Our Free Insomnia Resource Guide

Phenibut and Kratom for Opioid Withdrawal?

Many people reported using kratom combined with phenibut for opioid withdrawal. We caution against this, though, as no clinical studies have investigated this drug or kratom – alone or combined – for reducing opioid withdrawal symptoms.

A few Russian studies mention phenibut as an option, although baclofen is better studied. As for kratom, it may reduce withdrawal symptoms since it activates opioid pathways. But it can also cause liver damage and other serious side effects [49].

What’s more, a PubMed search of phenibut and kratom does not return any results. The exact interactions and risks of their combined use are completely unknown.

Plus, both phenibut and kratom are addictive themselves. Combining them creates another kind of “high” that may be equally addictive as narcotics, dangerous, and can cause complicated withdrawal symptoms.

Does Phenibut Enhance Exercise Performance and Libido?

No, there are no studies about the effects of phenibut on exercise performance or libido enhancement. Animal studies that show natural GABA can boost performance and growth hormone production [50].

But while GABA is a natural substance, phenibut is a different, chemically modified molecule. We can’t conclude that it will have the same effects.

In studies on people with chronic fatigue or poor brain circulation, phenibut improved energy levels. It also has anxiety-reducing euphoric effects. So when these add up, we can understand its potential to indirectly improve exercise performance and sexual function. This is still questionable, though [2].

Side Effects and Cautions

At SelfHacked, we believe that phenibut should not be taken lightly, without the guidance of a doctor. This substance can cause side effects, has abuse potential, and should not be considered as a supplement (although classified as such), but rather as a medication [51].

Phenibut can be toxic, especially in high doses. Side effects include [52, 53, 3]:

  • Headaches
  • Low blood pressure and increased heart rate
  • Loss of consciousness
  • Sedation and sleepiness
  • Agitation
  • Excessive muscle relaxation or tremors
  • Hallucinations
  • Nausea and vomiting
  • Tolerance
  • Serotonin syndrome

Side effects are much more likely at doses over 1 g/day, while high doses (3 g/day or more) can be very dangerous. Two people with high phenibut blood levels experienced delirium and decreased consciousness [54, 52].

Mixing Phenibut and Alcohol

Phenibut and alcohol should not be mixed. Both alcohol and phenibut increase GABA activity in the brain and cause sedation. When combined, the effects are intensified, increase the risk of overdose, and may cause a loss of consciousness and serious mental disturbances [2, 55].

Both phenibut and alcohol are addictive and can cause dependence. Dependence on both is harder to overcome and the withdrawal may be more severe [56].


In one case, phenibut overdose caused confusion, seizures while walking, shallow breathing, low body temperature, and reduced consciousness [57].

In another case, a man who took 30 g of phenibut powder bought on the internet had to be admitted to the ICU and intubated. He was going through phases of agitation, sleepiness, muscle jerking [53].


Phenibut withdrawal symptoms include [58, 51, 53]:

  • Severe rebound anxiety
  • Panic attacks
  • Restlessness and irritability
  • Dizziness
  • Fatigue
  • Loss of appetite
  • Insomnia
  • Muscle twitches and tremors
  • Heart palpitations
  • Hallucinations
  • Confusion
  • Derealization and depersonalization
  • Increased sensitivity to light and sound
  • Nausea

Tolerance can develop quickly, causing people to take higher and higher doses, which worsens the side effects. It also makes stopping this drug difficult and the withdrawal severe, as people get used to its calming effects [9].

The severity of the withdrawal depends on how long it was used for, the dosage, and individual differences [9].

Natural Alternatives and Substitutes

GABA itself is naturally produced in the brain, but less so in people with anxiety, depression, or under stress. But just taking pure GABA supplements won’t boost its brain levels, since it can’t cross into the brain.

There are various natural ways to increase GABA with herbal supplements or by engaging in stress-reduction activities. These won’t give you the “high” of sudden GABA boosts like synthetic drugs will, but are much healthier in both the short- and long-run.

These natural methods can help people with anxiety and potentially also those looking to wean off phenibut and lessen the withdrawal symptoms.

Some calming, GABA-enhancing herbal supplements include:

Lifestyle changes that boost GABA and reduce stress include:

Stimulating the vagus nerve will also boost GABA in the brain.

Limitations and Caveats

Many of the studies mentioned and described here are in Russian and limited to animal experiments.

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