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

Updated on March 18, 2024
 by — reviewed by Jason Williams, PhD (Contributor: George Collins / Editor: Yoko Hill)
An overview of Phenibut's nootropic benefits, uses, and side effects.

Phenibut is similar to the neurotransmitter GABA (gamma-aminobutyric acid), and has garnered significant attention as a dietary supplement. A substance originally developed in Russia during the 1960s for use in Eastern European countries, phenibut is often used to alleviate social anxiety, stress disorders, and insomnia.

The effects of phenibut on the central nervous system also have cognitive-enhancing benefits, making it a potential nootropic (also known as a smart drug) for those looking for this benefit.

Phenibut is now legal and commonly found in dietary supplements throughout the U.S, despite limited research on its clinical effects.

We will explore this nootropic and its effects, the science behind its use, and the real-world implications of incorporating this compound into a dietary regimen. The goal is to provide a comprehensive understanding of phenibut as a nootropic drug, guiding people through the complexities of its use, the potential risks involved, and the necessary precautions to avoid phenibut abuse.

Is this the right nootropic supplement for you? Let’s find out.

What is Phenibut?

Phenibut is a close cousin to drugs in the benzodiazepine family and is scientifically known as 4-amino-3-phenyl-butyric acid. Phenibut is a psychoactive nootropic compound that’s used to treat acute anxiety and post-traumatic stress disorder. Phenibut is sometimes included in dietary supplements marketed for anxiety, sleep, or cognitive enhancement.(1) 

However, its inclusion in these products is controversial and not regulated in many countries because phenibut is dangerous when used recreationally. Some users report euphoric effects, which contribute to its potential for misuse, and symptoms can include withdrawal. 

If you’re considering this nootropic drug (also known by the brand name Noofen), responsible usage is key in order to avoid your supplementation leading to an addiction. When using phenibut, it’s important to be aware of the potential risks and side effects, particularly with long-term use and large doses.

Phenibut acts on the brain by mimicking the neurotransmitter GABA, which has a calming effect on the nervous system, which is why it’s a potential treatment for anxiety disorders. Phenibut is also sometimes used off-label for its potential mood-enhancing properties due to the feelings of euphoria it provides. However, its effectiveness and safety for treating depression are not well-established.

Medically, phenibut has been used in some countries to treat conditions like anxiety, insomnia, and alcoholism, but it is not widely accepted or used in standard medical practice in many parts of the world.

Phenibut is typically most well-known for its ability to reduce anxiety, the primary reason it’s used, both medically and recreationally. However, more research on this nootropic substance is needed.

Although this nootropic drug is not approved by the Food and Drug Administration (The FDA does not currently include dietary supplements on its list), phenibut is legal to be sold online.


  • Ability to treat anxiety disorders and boost mood
  • Improved focus, alertness, and cognitive performance
  • Potential treatment for alcoholism and depression


  • Phenibut users are at risk for potential phenibut dependence and withdrawal
  • Limited research on phenibut is available to verify its long-term safety profile

Mechanism of Action

R-phenibut refers to one of the enantiomers of the drug phenibut. Phenibut, a central nervous system depressant with psychoactive effects, exists in two forms, R-phenibut and S-phenibut.

Here is an overview of phenibut’s mechanism of action: 

  1. GABA-B Receptor Agonist: The primary mechanism of action of phenibut is as an agonist at the GABA-B (gamma-aminobutyric acid type B) receptors. GABA is the primary inhibitory neurotransmitter in the brain, and its activation leads to a decrease in neuronal excitability throughout the nervous system. By stimulating GABA-B receptors, phenibut exerts anxiolytic (anti-anxiety), sedative, and muscle relaxant effects.(2)
  2. GABA-A Receptors: At higher doses, phenibut may also exert some effects on GABA-A receptors, though this action is less significant compared to its effect on GABA-B receptors.(3) Receptor by Agonists and Positive Allosteric Modulators.” Journal of medicinal chemistry vol. 58,16 (2015): 6336-47. doi:10.1021/jm5018913)) The interaction with GABA-A receptors might contribute to its sedative properties, similar to the action of benzodiazepines, though through a different binding site.
  3. Voltage-Gated Calcium Channels: Phenibut also appears to bind to and block certain voltage-dependent calcium channels, particularly those containing the α2δ subunit. This action is similar to that of certain drugs used to treat neuropathic pain, like gabapentin and pregabalin. This mechanism may contribute to phenibut’s analgesic (pain-relieving) and potential nootropic (cognitive-enhancing) effects.
  4. Pharmacokinetics: Phenibut is well-absorbed orally and crosses the blood-brain barrier more effectively than GABA itself. Its effects typically begin within 2-4 hours of ingestion and can last up to several hours, depending on the dose and individual metabolism.
  5. Potential for Abuse: The inclusion of phenibut in dietary supplements is a concern due to its potential for abuse and side effects. In supplements, phenibut is often marketed for its anxiolytic and nootropic effects, but users may not be fully aware of the risks, especially at high doses. Besides its desired effects, phenibut can cause an overdose when incorrectly dosed. 

Understanding the mechanism of action of phenibut is crucial for both medical professionals and users, as it helps in assessing the risks and benefits of its use. The potential for abuse and the risks associated with high doses or long-term use should be carefully considered.

Nootropic Benefits of Phenibut

Phenibut has been used both as a nootropic drug and as a treatment for various conditions. Here’s an overview of its nootropic benefits, along with pertinent considerations.

1. Treatment for Anxiety

Phenibut has been used to reduce anxiety, particularly social anxiety, due to its calming effects on the brain.(4)

2. Improved Cognitive Function

As a nootropic, phenibut is sometimes claimed to enhance cognitive function, though scientific evidence supporting this is limited. Some theorize that by reducing stress and anxiety levels, the brain can function better and phenibut users can experience a clearer sense of cognition.(5)

3. Stress Reduction

Some people use phenibut to manage symptoms of stress and improve their ability to cope with stressful situations.(6)

4. Sleep Aid

Phenibut has been used to treat insomnia, helping to induce sleep and improve sleep quality.(7)

5. Mood Enhancement

Users often report a mood-enhancing effect, including feelings of relaxation and euphoria.

6. Alcohol Withdrawal Aid

In some cases, phenibut has been used to alleviate symptoms associated with alcohol withdrawal.

Uses of Phenibut

Phenibut has several uses, mainly related to its psychoactive effects.

Here are some of the primary uses of phenibut:

  • Anxiety Reduction: Phenibut is most commonly used for its anxiolytic (anti-anxiety) effects. It helps to calm the brain and may be effective in reducing symptoms of anxiety, including social anxiety.
  • Insomnia Treatment: Due to its sedative effects, phenibut can be used to improve sleep quality and treat insomnia. It helps induce sleep and may lead to a more restful night’s sleep.
  • Stress Reduction: Phenibut has calming effects that can be beneficial in managing and reducing stress.
  • Mood Enhancement: Some users experience mood enhancement or euphoria, making it a sought-after substance for those looking to improve their overall sense of well-being.
  • Alcohol Withdrawal Aid: In some cases, phenibut has been used to alleviate symptoms associated with alcohol withdrawal.
  • Cognitive Enhancement: There is some anecdotal evidence that phenibut may have nootropic effects, potentially improving cognitive functions like memory, attention, and learning capacity.
  • Treatment for Vestibular Disorders: In some countries, phenibut is used to treat vestibular (balance) disorders, as it can have a stabilizing effect on the vestibular system.
  • Muscle Relaxation: Phenibut may exert muscle relaxant effects, which can be beneficial in certain medical conditions or for individuals with muscle tension.

Where to Buy Phenibut

Phenibut is legal to possess and sold online in powder form.

Our top pick for the best phenibut retailer is Science.Bio.

Science.Bio sells phenibut to users worldwide, with a reliable and trustworthy reputation. They offer some of the highest quality nootropics that have been third-party tested.

Phenibut’s prevalence of use varies by region and is influenced by factors such as legal status, awareness, and availability. Since phenibut use can be dangerous, it’s vital to source phenibut powder from reputable online companies.

Phenibut Dosage

The appropriate dosage of phenibut can vary significantly based on individual factors like tolerance, the condition being treated, and personal sensitivity to the substance. However, there are general guidelines that can be followed:

  1. Starting Dose: For new users, it’s often recommended to start with a lower dose to assess tolerance. This can be around 250-500 mg.
  2. Typical Therapeutic Dose: For therapeutic effects, such as anxiety reduction or sleep aid, doses often range from 250 mg to 750 mg per dose. These are generally taken up to three times a day, spaced evenly.
  3. Maximum Dosage: To reduce the chances of becoming dependent on phenibut, it’s generally recommended not to exceed 2000 mg (2 grams) per day. Higher doses increase the risk of side effects and the potential for abuse and withdrawal from phenibut.

Phenibut Side Effects and Safety

Phenibut’s ability to induce euphoria and calmness at low doses has led to its recreational use. However, this can quickly escalate to dependence and withdrawal, as the body develops tolerance, requiring higher doses to achieve the desired effects. Phenibut withdrawal symptoms can be severe, ranging from agitation and insomnia to psychosis and severe withdrawal syndrome, akin to alcohol withdrawal.

Moreover, the unregulated nature of phenibut means that users often self-dose, leading to an increased risk of drug abuse and overdose.

At high doses, phenibut can cause significant side effects, including severe drowsiness, nausea, dizziness, and at very high doses, it can depress the central nervous system to a dangerous level. High doses of phenibut might also increase the risk of developing tolerance and dependence.

Phenibut overdose symptoms may include unconsciousness and even psychosis in severe cases when there are acute toxicity levels.(8)

As a substance use disorder, phenibut addiction requires professional addiction treatment, especially when co-occurring mental health issues are present.(9) If you experience any signs of phenibut dependence, get help from your nearest Drug Addiction Centre. Speak to your healthcare provider to further understand the steps you need to take.

With this physical dependence potential in mind, phenibut is safe to use and typically well tolerated when taken responsibly. Clinical trial analysis of phenibut side effects reported adverse effects in only 5.66% of human patients, and the most reported side effect was the increased need to sleep (somnolence).(10)

However, like most nootropics, there are still some common side effects and key considerations you need to know before taking phenibut:

  1. Gastrointestinal Issues: Some users experience gastrointestinal side effects like nausea, upset stomach, and diarrhea.
  2. Mood Changes: Though phenibut is used by some for mood enhancement, it can also cause mood swings, irritability, and changes in emotional well-being.
  3. Medication Interactions: As a medication, phenibut can interact with other substances that modulate the GABA system, such as benzodiazepines and alcohol. This can potentially lead to enhanced effects or increased risks of side effects.


Originally designed for theraputic use in Russia, phenibut is a potent nootropic with potent anxiolytic effects. It’s especially beneficial for reducing stress and can help you to feel more relaxed and well-rested. Phenibut is also a great cognitive enhancer, promoting focus, concentration, and mental clarity.

However, Phenibut can cause dependence and tolerance, so it’s important to start with a lower dose to assess your response.

Remember to consult with a healthcare provider if you’re considering adding a new dietary supplement to your daily wellness routine. A doctor will help you navigate the best ways to use phenibut without putting yourself at risk of its potential adverse effects.  


How long does phenibut take to work?

Phenibut usually starts working within 2-4 hours of ingestion. However, the onset time can vary based on personal factors like metabolism, body mass, and stomach content.

What is the elimination half-life of phenibut?

The elimination half-life of phenibut is approximately 5.3 hours. This means that, on average, it takes around 5.3 hours for half of the drug to be removed from the body.

Should you cycle phenibut?

Yes, phenibut should be cycled to avoid tolerance and dependency. It’s not recommended for daily use due to its addictive nature. A common strategy is to use it for a maximum of two days per week.

Can I stack phenibut with other nootropics?

Yes, phenibut can be stacked with other nootropics, but caution is needed due to potential interactions. Always consult a healthcare professional before starting a new supplement regimen.

How should I store phenibut?

Phenibut should be stored in a cool, dry place out of direct sunlight. Ensure it’s kept out of reach of children and pets to prevent accidental consumption.

Sources, Studies, and Scientific Research
  1. Lapin, I. “Phenibut (beta-phenyl-GABA): a tranquilizer and nootropic drug.” CNS drug reviews vol. 7,4 (2001): 471-81. doi:10.1111/j.1527-3458.2001.tb00211.x ↩
  2. Zyablitseva, Evgeniya A et al. “The effects of agonists of ionotropic GABA(A) and metabotropic GABA(B) receptors on learning.” The Spanish journal of psychology vol. 12,1 (2009): 12-20. doi:10.1017/s1138741600001438 ↩
  3. Brown, Katie M et al. “Activation of the γ-Aminobutyric Acid Type B (GABA(B ↩
  4. Ziablintseva, E A, and I V Pavlova. Rossiiskii fiziologicheskii zhurnal imeni I.M. Sechenova vol. 95,9 (2009): 907-18. ↩
  5. Robinson, Oliver J et al. “The impact of anxiety upon cognition: perspectives from human threat of shock studies.” Frontiers in human neuroscience vol. 7 203. 17 May. 2013, doi:10.3389/fnhum.2013.00203 ↩
  6. Behmer Hansen, Ryan A et al. “Reasons for use and experiences of using phenibut, a mixed methods analysis of online reports.” The American journal of drug and alcohol abuse vol. 49,4 (2023): 458-469. doi:10.1080/00952990.2023.2204510 ↩
  7. Danilin, V P et al. “Vliianie fenibuta na nochnoĭ son bol’nykh s alkogol’nym abstinentnym sindromom” [Effect of fenibut on the nocturnal sleep of patients with the alcoholic abstinence syndrome]. Zhurnal nevropatologii i psikhiatrii imeni S.S. Korsakova (Moscow, Russia : 1952) vol. 86,2 (1986): 251-4. ↩
  8. Weleff, Jeremy et al. “Clinical Presentations and Treatment of Phenibut Toxicity and Withdrawal: A Systematic Literature Review.” Journal of addiction medicine vol. 17,4 (2023): 407-417. doi:10.1097/ADM.0000000000001141 ↩
  9. Graves, Janessa M et al. “Notes from the Field: Phenibut Exposures Reported to Poison Centers – United States, 2009-2019.” MMWR. Morbidity and mortality weekly report vol. 69,35 1227-1228. 4 Sep. 2020, doi:10.15585/mmwr.mm6935a5 ↩
  10. Kupats, Einars et al. “Safety and Tolerability of the Anxiolytic and Nootropic Drug Phenibut: A Systematic Review of Clinical Trials and Case Reports.” Pharmacopsychiatry vol. 53,5 (2020): 201-208. doi:10.1055/a-1151-5017 ↩