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Phenibut Availability, Statistics & Overdose Potential

While officially legal in the United States as many nootropic drugs are not yet tightly regulated, phenibut is a potentially hazardous synthetic drug initially created to combat anxiety. It is easy to find on the internet in tablet and powder form, even though it is unapproved and remains unregulated.

Phenibut is marketed as a sleep aid, to help with relaxation and to decrease anxiety. The drug is often used recreationally with similar effects to other central nervous system (CNS) depressants like benzodiazepines.

Phenibut use can cause a variety of potentially serious side effects, and overdose can lead to coma and death.1 Repeated use of phenibut can lead to dependency and severe withdrawal symptoms.1 It is a potentially dangerous substance of abuse that should be avoided.

Easily Accessible

Phenibut is a nootropic drug, which means it is a synthetic substance meant to enhance brain function in some way. It is not regulated and not approved for use in the United States.

It has, however, been found present in dietary supplements used to improve mood and cognition and in sleep aids. The U.S. Food and Drug Administration (FDA) does not approve its use and has issued warning letters to companies marketing it this way.2

Phenibut was created in the 1960s as a Russian antianxiety drug, and it works on the GABA-B (gamma-aminobutyric acid subtype B) receptors as a CNS depressant with mood and brain-enhancing effects.6 It is not sold or approved for pharmaceutical use in the United States, but it can be found over-the-counter as a supplement. It is readily accessible through online retailers.

Alternative Names

In other countries, phenibut is sold under these brand names: Anvifen, Fenibut, and Noofen.

As it has no approved medical use in the United States, it is not available as a pharmaceutical product or at a pharmacy. Instead, it is marketed as a supplement or nootropic.

Phenibut is marketed under the following names:

  • PhGaba
  • Phenigam
  • Phenigamma
  • Phenygam
  • 4-amino-3-phenylbutanoic acid
  • Beta– (Aminomethyl) hydrocinnamic acid
  • Beta- (aminomethyl) benzenepropanoic acid
  • β-phenyl-γ-aminobutyric acid


Phenibut Use & Abuse

Phenibut use appears to be on the rise based on the number of calls for exposure to the substance to poison control centers, the Centers for Disease Control and Prevention (CDC) reports.1

  • Between 2009 and 2019, there were 1,320 calls to poison control centers involving phenibut exposure.
  • Cases have risen from only a few each year to 300–400 per year in 2018 and 2019.
  • Most of the exposures involving phenibut are people between the ages of 18 and 34 (nearly 60 percent), and over three-quarters of these exposures were males.
  • Phenibut is most often found in tablet (65.1 percent) or powder form (24.8 percent).
  • Most often ingested orally, phenibut is also inhaled.
  • About one-third of the time, phenibut is used with other substances.

Additional statistics on phenibut use show that it is most often used recreationally as a drug of abuse.3

Overdose Risk With Phenibut

One case study showed that high doses of phenibut (more than 50 mg at a time) caused CNS suppression, lowered the pain response, and had tranquilizing effects.4 Of the poison control exposure calls regarding phenibut, at least 10 percent who report taking only this substance reported serious side effects.1

Phenibut slows down breathing, heart rate, and motor functions. Especially when taken with other drugs that suppress the CNS or alcohol, it has a serious risk for overdose. Among calls to poison control regarding phenibut, 80 people ended up in coma and 3 people died.

A phenibut overdose and phenibut-related toxicity can cause the following:

  • Trouble breathing
  • Low pulse
  • Decreased blood pressure
  • Sluggish movements
  • Slurred speech
  • Anxiety and confusion
  • Tremors and seizures
  • Decreased motor control
  • Psychosis

Phenibut has a high potential for overdose-related toxicity. It is not monitored or controlled, and it can be difficult to know exactly what the substance contains. Mixing phenibut with other drugs or alcohol greatly increases the risk for a potentially fatal overdose.

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Tolerance & Withdrawal Involving Phenibut

Similar to other drugs impacting levels of GABA in the brain and suppressing the CNS, such as benzodiazepines (benzos), phenibut use can lead to tolerance and dependence.7

Chronic use of phenibut, much like benzos, can cause significant withdrawal symptoms when the drug processes out of the system. Although large-scale studies are not yet available for this substance, initial case studies indicate that stopping phenibut suddenly after a tolerance has developed can be life-threatening and require hospitalization.5

Withdrawal side effects experienced by patients in case studies have included the following:

  • Lowered appetite
  • Anxiety
  • Insomnia
  • Dizziness
  • Agitation
  • Heart palpitations
  • Depression
  • Tremors and possible seizures
  • Nausea and/or vomiting
  • Fatigue
  • Decreased ability to concentrate and think clearly
  • Potential auditory and visual hallucinations
  • Delusions

Like with benzos, withdrawal from phenibut can be serious and even potentially fatal. Immediate medical attention is needed.

Phenibut use can quickly cause the brain and body to become dependent on its sedative effects. This will mean that more and more of the drug is needed to feel its impact. Repeated use and increased dosage can lead to drug dependence and addiction, with serious withdrawal symptoms occurring when attempting to stop use of the drug.

Phenibut dependence and addiction are best managed with a team of professionals who can carefully manage the detox process from the drug, lessening physical and psychological withdrawal symptoms. Detox should be followed by comprehensive addiction treatment.

Learn more about Phenibut Legal Status & Current Legislative Action