Fenibut is one of the various trade names for a nootropic drug called Phenibut. Other names for this synthetic molecule include Noofen, Anvifen, and Phenygam.
Fenibut powder and capsules have anxiolytic and sedative effects. They are used to reduce anxiety, induce relaxation, and increase prosocial behavior.
Fenibut has not been reviewed by the US FDA and is not approved for clinical use. However, in Russia and some other countries, it is prescribed for mood disorders and certain health conditions.
In the USA, Canada, and parts of Europe, fenibut is sold online as a nootropic agent to support mental calmness, stress relief, normal sleep patterns and mental focus.
Fenibut is an analog of the inhibitory neurotransmitter GABA (gamma-aminobutyric acid). GABA is involved in regulating over-excitement of the CNS (central nervous system) and counterbalanced the effects of excitatory neurochemicals like glutamate.
While use of this drug under doctor supervision is generally well tolerated, it poses a risk of abuse and can be dangerous if taken in excessive dosages. Like other GABAergic compounds, it can cause tolerance, dependence and withdrawal if misused.



- Powerful anxiolytic for stress reduction
- Stimulates GABA receptors & supports sleep
- Neuroprotective & supports cognitive function
Fenibut Review
Related Topics
- What is Phenibut?
- User Review
- Benefits and Uses
- Dosage Recommendations
- Effects & Mechanisms of Action
- Experience Reports
- Anti-Anxiety Effects
- Using Phenibut for Sleep
- How to Take
- Negative Side Effects
- Withdrawal Dangers
- Risks with Alcohol Combination
- Comparison to Picamilon
- Buying Phenibut Guide
- Using Bulk Powder
- Primaforce Phenibut Review
- SNS Phenibut XT Review
This neuropsychotropic drug was developed during the 1960s in the Soviet Union (now Russia).
It is a phenylated analog of GABA and is believed to mimic some of GABA’s inhibitory effects in the CNS.
This nootropic compound was reportedly given to members of the Soviet Cosmonaut program to help them relax and quiet the mind while on long space missions.
According to interviews with former Soviet cosmonauts, it was found to help them focus better on their work and induce calmness, but without impairing their cognitive function.
Today, it is used clinically for health conditions such as vertigo, Meniere’s disease, Anxious-Neurotic conditions, alcohol withdrawal and post-traumatic stress disorder.
It is also taken off-label by individuals who want to overcome feelings of social anxiousness and improve their ability to speak in public.
According to a translated version of the patient instructions distributed with Phenibut in some Eastern European countries, “Attention, memory, speed of reaction and accuracy are improved under the effects of the medicine.”
Wikipedia reports that fenibut: [1]
- Is well-absorbed with roughly 63% bioavailability when taken orally;
- Has a 2-4-hour action onset in most users when taken orally;
- Has a biological half-life of about 5.3 hours;
- Is excreted 63% unchanged via urine;
- Has a 15-24-hour duration of action;
- Melts at 253 C (487 F);

- Powerful anxiolytic for stress reduction
- Improves sleep and may reduce insomnia
- Neuroprotective and cardioprotective effects
How Does Fenibut Work?
Fenibut works by mimicking some of the effects of an inhibitory neurotransmitter in the brain. It appears to activate GABA receptors that play a role in regulating mood, arousal, mental activity and more.
Neurotransmitters are chemicals used to facilitate neuronal (nerve-based) signaling. A neurotransmitter may be either excitatory or inhibitory.
Glutamate is the most prevalent neurotransmitter in humans and is the primary excitatory neurotransmitter. GABA is the primary inhibitory neurotransmitter used to keep the excitatory effects of glutamate in check.
Fenibut’s scientific name is beta-phenyl-gamma-aminobutyric acid (beta-phenyl-GABA). It is a phenylated derivative of the GABA molecule (C4H9NO2), which means that it contains GABA with the addition of a phenyl ring.
In addition to acting as an inhibitory brain chemical, GABA is an amino acid and is also directly involved with maintaining muscle tone. Humans can synthesize GABA endogenously from the glutamate neurotransmitter and a special form of vitamin B6 (pyridoxine).
Many people take synthetic GABA supplements to support mood, focus, muscle growth and more.
However, this type of GABA administered orally cannot get past the blood-brain barrier (BBB) very well, making supplementation largely ineffective, especially for any nootropic benefits.
The fenibut molecule is a GABA molecule with an added phenyl ring (C6H5). The phenyl ring makes the molecule better able to cross the BBB because it uses a different brain transport mechanism.
Once inside the Central Nervous System, fenibut mimics GABA’s actions at both GABA-A receptors and GABA-B receptors. It is said to stimulate the GABA-B receptors considerably more than it does GABA-A receptors.
Fenibut has also been reported to affect the “feel-good” neurotransmitter called dopamine. It also antagonizes an endogenous anxiety-reducing chemical called PEA (beta-phenylethylamine).
GABAergic Effects
Baclofen is a prescription-only drug used to relax muscles and prevent or stop spasms. It is a derivative of the fenibut molecule.
Fenibut is said to have similar anticonvulsant effects to baclofen and to a naturally-occurring neurotransmitter called gamma-hydroxybutyrate (GHB).
Further, like gabapentinoids like gabapentin and pregabalin, fenibut is able to block activities in voltage-gated calcium channels.
This drug has not been well-studied in humans and more research is required to understand its mechanisms of action.
In animal studies, it has been shown to:
- Decreased the desire to drink alcoholic beverages;
- Decreased alcohol-induced behavioral disorders;
- Decreased respiration rate;
- Increased heart rate;
- Induced sedation;
- Reduced anxiety;
Fenibut also appears to decrease the occurrence of respiratory arrest due to excessive administration of serotonin, a different excitatory neurotransmitter.
Researchers have also investigated potentials for preventing or reducing cardiovascular toxicity in laboratory studies.
Fenibut also seems to improve spontaneous movement after traumatic brain injuries and to prevent decreased cerebral circulation.
More research in double-blind placebo-controlled clinical trials is needed to fully understand how fenibut works in humans.

- Most effective supplements to improve mood
- Optimize levels of dopamine, serotonin and GABA
- Protect against stress and anxiety
What Is Fenibut Used For?
In Russia and some nearby countries, Fenibut is prescribed by doctors to prevent or treat various conditions including:
- Anxiety and fear before medical procedures or diagnostic tests;
- Various disorders characterized by asthenia (loss of strength);
- Poor sleep in psychosomatic or neurotic patients;
- PTSD (post-traumatic stress disorder);
- Vestibular (balance) disorders;
- Drug withdrawal symptoms;
- Kinetosis (motion sickness);
- Tension, anxiety, and fear;
- Stuttering and tics;
- Depression;
The Natural Medicines Comprehensive Database (NMCD) states that fenibut is also used to treat alcoholism, alcohol withdrawal syndrome, fatigue, and arrhythmia (irregular heartbeat). [2]
Nootropic supplement and stacks with this ingredient have been used to support memory function, learning, and enhancing overall cognitive function. However, there is limited research into the effects of this compound on brain performance.
Orally, phenibut is used for anxiety, alcoholism; arrhythmia; fear; insomnia; tension; stress; fatigue; post-traumatic stress disorder (PTSD); depression; and for improving memory, learning, and cognition.
You should discuss beginning to use fenibut capsules or powder for any purpose with your doctor beforehand.
Is Fenibut Safe?
You should not use fenibut nootropic supplements if you: [3]
- Have hepatic (liver) or renal (kidney) insufficiency;
- Are pregnant or breastfeeding an infant;
- Have gastrointestinal ulcers;
- Are under 3 years old;
- Drink alcohol;
In healthy people and with appropriate short-term or occasional use, fenibut is well-tolerated in most users who take it under doctor supervision.
Improper use of this nootropic drug can cause side effects including nausea, vomiting, sedation, irritability, allergic reactions, anxiety, dizziness, headache, or somnolence (sleepiness).
Fenibut should be taken in small doses between 250-500 milligrams up to 3 times daily. Treatment should not exceed 3 weeks before cycling off for an equal amount of time.
Loss of balance, headache and other hangover symptoms are possible with larger doses.
Never exceed more than 2500 milligrams (2.5 grams) in one day.
There is no known antidote for phenibut overdose. Taking too much is treated with stomach flushing, activated charcoal, inducing vomiting, and gastric lavage.
Many users build a tolerance to fenibut quickly and report taking higher dosages than what is recommended. Dependence or addiction is a serious and real possibility for users who do not exercise discipline while using this potent nootropic and anxiolytic.
Fenibut withdrawal symptoms can include audio and visual hallucinations, acute psychosis, extreme sedation, severe rebound anxiety, anger, and chronic insomnia.
Do not use fenibut powder or capsules before engaging in potentially dangerous activities like operating heavy machinery.
This compound may potentiate the effects or side effects of various other CNS depressants like alcohol, benzodiazepines, sedatives, opioids, barbiturates, antipsychotics, anticonvulsants, and anxiolytics.
If you are currently being treated for a medical condition or are taking prescription drugs, it is important to consult with a doctor before taking Fenibut pills to determine whether they are appropriate for you.
- Wikipedia contributors. "Phenibut." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 12 Mar. 2018. Web. 12 Apr. 2018
- Natural Meidicnes Comprehensive Database. Phenibut Professional Monograph. Accessed April 13, 2018
- Lapin, I. Phenibut (beta-phenyl-GABA): a tranquilizer and nootropic drug. CNS Drug Rev. 2001 Winter;7(4):471-81. Accessed April 13, 2018
Article last updated on: July 8th, 2018 by Nootriment