Phenibut is not approved by the FDA for any medical use in the United States. Of 1,320 phenibut exposures reported to U.S. poison centers during 2009–2019, 12.6% were life-threatening or resulted in significant disability, and three deaths were reported (CDC, MMWR, 2020). It causes dependence and withdrawal with regular use, so it is not a safe consumer supplement.

Is phenibut legal in the United States?

Phenibut is not a federally controlled substance in the United States, but it is not lawful to sell as a dietary supplement: the FDA has determined that phenibut does not meet the statutory definition of a dietary ingredient, and in April 2019 issued warning letters to companies marketing it as one. Alabama has separately made phenibut a Schedule II controlled substance under state law.

What are phenibut withdrawal symptoms?

Published case reports of phenibut withdrawal describe severe rebound anxiety, insomnia, tremor, sweating, agitation, visual hallucinations, autonomic instability, and in several reports frank psychosis and agitated delirium. Withdrawal has been reported to begin within a few days of stopping and to last one to several weeks. People who use phenibut regularly should not stop abruptly without medical guidance.

Can you overdose on phenibut?

Yes. Phenibut overdose has been reported to cause reduced consciousness, coma, respiratory depression requiring intubation, and seizures, with risk increased when it is combined with alcohol, benzodiazepines, or opioids. Coma was recorded in 6.2% of the 1,320 U.S. poison-center exposures reported during 2009–2019 (CDC, MMWR, 2020).

Does phenibut show up on a drug test?

No. Phenibut is not detected by standard urine drug screens or routine hospital toxicology panels, which is why phenibut withdrawal is repeatedly described in the literature as being mistaken for a primary psychiatric episode. A negative toxicology screen does not rule out phenibut.

What is phenibut sold as?

Phenibut is sold online and in some retail shops as a "nootropic," "cognitive enhancer," "mood booster," or sleep aid, commonly as a bulk powder with high-purity claims and no warning about dependence, withdrawal, or overdose risk.

In an emergency

Emergency: 911
Poison Control: 1-800-222-1222
Suicide & Crisis Lifeline: 988

If you use phenibut regularly, do not stop abruptly without medical guidance. Abrupt discontinuation has been associated with serious withdrawal, including agitation and psychosis. U.S. numbers shown.

Phenibut: the evidence base

Phenibut is a Soviet-era central nervous system depressant, prescribed as a medicine in Russia and sold in the United States as an unregulated powder marketed as a “nootropic.” It is not approved by the FDA for any use, and the FDA has determined it is not a lawful dietary ingredient — yet it is sold openly, without warning labels, to people who do not know it causes physical dependence.^[2,3]

This page is the citable evidence base: what the surveillance data shows, what it cannot show, what the published clinical literature describes, and where every claim came from. It is written for people who have to act on it — legislative staff, journalists, clinicians, and analysts.

What phenibut is

Phenibut (β-phenyl-γ-aminobutyric acid) is a synthetic central nervous system depressant developed in the Soviet Union in the 1960s.^[4] In Russia and several neighbouring countries it is a prescribed medicine for anxiety and related conditions. It is not an approved medicine in the United States, and the FDA has stated that it does not meet the legal definition of a dietary ingredient, which makes products selling it as a supplement misbranded.^[2,3,4]

Despite having no approved use, phenibut is widely available in the United States, sold online and in some retail shops as a “nootropic,” “cognitive enhancer,” or sleep aid, usually as a bulk powder with purity claims and no warning about dependence, withdrawal, or overdose.^[2,5]

Why people take it

Phenibut works. That is the part most warning material leaves out, and leaving it out makes the rest of the warning easy to dismiss. It is an effective anxiolytic — effective enough that it is a prescription medicine for anxiety in the country that developed it.^[4] People who use it report reduced social anxiety, sedation, and elevated mood, and those are the effects they are seeking.^[5]

The efficacy is not separate from the harm; it is the mechanism of it. The compound is reinforcing precisely because it delivers real relief, and tolerance to that relief develops within days to weeks of regular use, so the amount that worked stops working.^[4,9]

The danger of phenibut is not that it doesn’t work. It is that it works, and then stops working at the same amount, and then hurts you when you stop taking it.

How it works

Phenibut is structurally related to the brain’s main inhibitory neurotransmitter, GABA, with an added phenyl ring that lets it cross the blood-brain barrier. It acts primarily as an agonist at GABA-B receptors — the same receptor family as the prescription muscle relaxant baclofen — with some activity at GABA-A receptors.^[4]

Two consequences of that mechanism matter clinically. Its withdrawal syndrome resembles benzodiazepine and alcohol withdrawal, and baclofen has been used in published cases as a substitute at the same receptor during withdrawal management.^[7,8,11]

What the surveillance data shows

The only national U.S. surveillance series on phenibut is the CDC’s analysis of poison-center calls for the eleven years from 2009 to 2019.^[1] The number that matters in it is not the total. It is the severity.

12.6%

Roughly one in eight reported phenibut exposures was life-threatening or caused significant disability. Three deaths were reported over the period, and coma was recorded in 6.2% of exposures.Source: CDC, MMWR, U.S. poison-center exposures, 2009–2019.^[1]

The trend

Reported phenibut exposures were low through 2014 and rose sharply during 2015–2019. The CDC noted that the growing popularity and availability of phenibut through online retailers might be contributing factors.^[1] Surveillance data of this kind can show that reports rose alongside online availability; it cannot establish that one caused the other.

Who was affected

Phenibut exposures reported to U.S. poison centers, 2009–2019 (n = 1,320). All figures from the CDC MMWR report.^[1]
Total reported exposures	1,320
Life-threatening or significant disability	12.6%
Deaths	3
Coma	6.2%
Calls originating from healthcare facilities	85.0% (1,122)
Male	75.5%
Aged 18–34	58.4%
Mean age	31.7 years

The most commonly reported clinical effects were agitation (30.4%), drowsiness or lethargy (29.0%), tachycardia (21.9%), and confusion (21.3%).^[1]

What this data can and cannot tell you

These numbers are a floor, not a measurement. Poison-center figures are voluntary calls, not a national count, and the American Association of Poison Control Centers cannot verify the accuracy of every report.^[1]

85% of these calls came from healthcare facilities, which means the series largely captures cases already severe enough that someone reached a hospital. Everyone who developed dependence and never called anyone is invisible in it.

The data are also now several years old. No more recent national surveillance series on phenibut has been published. A reader who wants to know what is happening in 2026 cannot learn it from this source, and neither can we.

We state this first, and prominently, because it is the honest reading of the evidence. 1,320 reports over eleven years is a small number. The argument this site makes does not rest on the volume of reports; it rests on the severity rate within them, on the fact that severity is measured against a denominator that systematically excludes the undetected, and on a mechanism of dependence that is well described in the clinical literature.

Health risks, dependence, and withdrawal

Acute effects

The effects most frequently reported to poison centers are agitation, drowsiness or lethargy, rapid heart rate, and confusion.^[1] Severe presentations reported in poison-center data and in the case literature include reduced consciousness and coma, respiratory depression requiring intubation, and seizures.^[1,10,12]

Interactions

Phenibut is a central nervous system depressant, so combining it with alcohol, benzodiazepines, or opioids compounds sedation and respiratory depression. In the small number of deaths described in the literature, concurrent use of other substances, including alcohol and opioids, was documented.^[1,12]

Dependence and withdrawal

Regular use produces tolerance, and published case reports describe tolerance developing within one to two weeks.^[9] Physical dependence follows, and stopping after a period of regular use produces a withdrawal syndrome.

Published phenibut withdrawal cases describe rebound anxiety, insomnia, tremor, sweating, autonomic instability, agitation, visual hallucinations, and frank psychosis, with onset reported within a few days of stopping and duration running from about a week to several weeks.^[7,8,11] A 2023 systematic review of phenibut withdrawal identified only case reports and conference abstracts — there are no controlled trials, and no consensus management guideline exists.^[11]

Do not stop abruptly without medical guidance. Abrupt discontinuation after regular use is the circumstance in which the most serious reported withdrawal events occurred.

Reading this because of a specific person? Practical guidance on stopping phenibut is written for them rather than for a professional audience. Poison Control (1-800-222-1222) advises the public and clinicians alike, at no cost, at any hour.

What the clinical literature describes

The following are summaries, in our own words, of individual published case reports. They are included because they document what phenibut harm actually looks like when it reaches a hospital, and because each one can be independently retrieved and checked.

Each entry below is a single published case unless stated otherwise. A case report describes what happened to one patient. It does not establish how common that outcome is, and it is not evidence of a rate.

Tolerance can develop within weeks, and dependence with it^[9]

A man in his twenties presented to an emergency department asking for help with detoxification. He had begun using phenibut bought online roughly a month earlier while also drinking heavily, and had found that the amount that once worked stopped working — the report notes that tolerance to phenibut has been described as developing within one to two weeks. When he tried to stop on his own he developed cold sweats, anxiety, insomnia, and both visual and auditory hallucinations. His clinicians described a withdrawal that resembled alcohol withdrawal but ran longer and more severely than his drinking alone would explain, and concluded that phenibut dependence was adding to it. He was managed with benzodiazepines for the acute withdrawal alongside psychiatric medication for anxiety and protracted symptoms.

A single published case report. It describes what happened to one patient; it does not establish how often this happens.

Withdrawal can present as an agitated delirium that standard treatment does not touch^[7]

A woman in her fifties was brought to an emergency department with severe psychomotor agitation, disorganised thinking, visual hallucinations, and a complete inability to sleep. Her partner reported that the movement disturbance and fluctuating alertness had come on suddenly that morning. Her urine toxicology screen showed only benzodiazepines, which she used legitimately, and her presentation was initially read as a primary psychiatric episode. Benzodiazepines and antipsychotics did not work. The cause only became clear when her partner found phenibut at home and a poison centre was called; her symptoms had begun about three days after she stopped taking it, following months of regular use. She was treated with baclofen as a substitute at the same receptor, along with escalating benzodiazepines, antipsychotics chosen with cardiac monitoring in mind, and beta-blockers for blood-pressure and heart-rate instability. She was in hospital for roughly three and a half weeks, and her psychotic symptoms resolved by the fourth week.

A single published case report. Its value here is diagnostic: it documents a presentation that was missed precisely because the drug does not appear on a standard screen.

Withdrawal can outlast the hospital stay, and benzodiazepines can make it worse^[8]

A man in his thirties was admitted after a suicide attempt. He had been buying phenibut from internet vendors and escalating his use over a period of weeks, and described a dream-like, out-of-body state along with several days without sleep. On arrival he was tachycardic with dilated pupils and flushed skin, and although he remained oriented, his thinking was tangential and illogical. Withdrawal began on his second hospital day and brought agitation, disorientation, visual hallucinations, and tremor that lasted about a week. Notably, treatment with diazepam appeared to worsen rather than settle his condition; he was subsequently managed with baclofen and was clear-thinking and fully oriented by the ninth day.

A single published case report. The paradoxical response to a benzodiazepine is one observation in one patient, not an established pharmacological rule.

Acute presentations can require airway protection and intensive care^[10]

A man in his thirties with a history of polysubstance use was brought in by ambulance after being found at home behaving incoherently. He arrived agitated, confused, and resistant to care, with a Glasgow Coma Scale score in the mildly impaired range. Repeated intravenous lorazepam over a quarter of an hour had minimal effect, and he was intubated and mechanically ventilated because he could not cooperate with care safely. His urine screen was positive for benzodiazepines and cannabinoids; ethanol, salicylate, acetaminophen, and ammonia were all below detection, and his bloodwork showed a raised white cell count, lactic acidosis, and an elevated anion gap. He was admitted to intensive care, extubated two days later, and discharged home after psychiatric consultation.

A single published case report. Broader poison-centre and review literature describes central nervous system depression, coma, and respiratory depression requiring intubation in phenibut cases, particularly alongside other depressants.

Questions people ask

Is phenibut safe?: Phenibut is not approved by the FDA for any medical use in the United States. Of 1,320 phenibut exposures reported to U.S. poison centers during 2009–2019, 12.6% were life-threatening or resulted in significant disability, and three deaths were reported (CDC, MMWR, 2020). It causes dependence and withdrawal with regular use, so it is not a safe consumer supplement.
Is phenibut legal in the United States?: Phenibut is not a federally controlled substance in the United States, but it is not lawful to sell as a dietary supplement: the FDA has determined that phenibut does not meet the statutory definition of a dietary ingredient, and in April 2019 issued warning letters to companies marketing it as one. Alabama has separately made phenibut a Schedule II controlled substance under state law.
Is phenibut addictive?: Yes. Phenibut is an agonist at GABA-B receptors, and regular use produces tolerance and physical dependence; published case reports describe tolerance developing within one to two weeks of regular use. Stopping after regular use can cause rebound anxiety, insomnia, tremor, agitation, and in published cases psychosis.
What are phenibut withdrawal symptoms?: Published case reports of phenibut withdrawal describe severe rebound anxiety, insomnia, tremor, sweating, agitation, visual hallucinations, autonomic instability, and in several reports frank psychosis and agitated delirium. Withdrawal has been reported to begin within a few days of stopping and to last one to several weeks. People who use phenibut regularly should not stop abruptly without medical guidance.
Can you overdose on phenibut?: Yes. Phenibut overdose has been reported to cause reduced consciousness, coma, respiratory depression requiring intubation, and seizures, with risk increased when it is combined with alcohol, benzodiazepines, or opioids. Coma was recorded in 6.2% of the 1,320 U.S. poison-center exposures reported during 2009–2019 (CDC, MMWR, 2020).
Does phenibut show up on a drug test?: No. Phenibut is not detected by standard urine drug screens or routine hospital toxicology panels, which is why phenibut withdrawal is repeatedly described in the literature as being mistaken for a primary psychiatric episode. A negative toxicology screen does not rule out phenibut.
What is phenibut sold as?: Phenibut is sold online and in some retail shops as a "nootropic," "cognitive enhancer," "mood booster," or sleep aid, commonly as a bulk powder with high-purity claims and no warning about dependence, withdrawal, or overdose risk.

Primary sources and help

If you need help rather than research

This site is a reference for people acting on phenibut in a professional capacity. If you are reading it because of a specific person, the practical resources are these: Poison Control at 1-800-222-1222 is free, staffed by toxicologists, available 24 hours a day, and will advise clinicians as readily as families. SAMHSA’s FindTreatment.gov locates treatment services.

The sources this page rests on

CDC MMWR: phenibut exposures reported to poison centers, 2009–2019 — the surveillance series in §3.
FDA: phenibut in dietary supplements — the federal determination that it is not a lawful dietary ingredient.
Systematic review of phenibut withdrawal (Clinical Toxicology, 2023) — the best available synthesis, and an honest account of how thin the evidence base is.
National Capital Poison Center: phenibut — a plain-language secondary summary.

Corrections and contact

If something on this page is wrong, we want to know, and we will correct it and say that we did. Corrections, questions, and information from people with relevant expertise are all welcome.

This mailbox is checked periodically by the site’s volunteer operator. It is not monitored continuously and must not be used for emergencies — use the numbers at the top of this page.

References

Graves JM, Dilley J, Kubsad S, Liebelt E. Notes from the Field: Phenibut Exposures Reported to Poison Centers — United States, 2009–2019. MMWR Morbidity and Mortality Weekly Report. 2020;69(35):1227–1228. doi:10.15585/mmwr.mm6935a5. cdc.gov/mmwr (PMID 32881852)
FDA acts on dietary supplements containing DMHA and phenibut. U.S. Food and Drug Administration, Constituent Update. 2019. fda.gov
Phenibut in Dietary Supplements. U.S. Food and Drug Administration. n.d.. fda.gov
Lapin I. Phenibut (β-phenyl-GABA): a tranquilizer and nootropic drug. CNS Drug Reviews. 2001;7(4):471–481. doi:10.1111/j.1527-3458.2001.tb00211.x. PMID 11830761
Owen DR, Wood DM, Archer JR, Dargan PI. Phenibut (4-amino-3-phenyl-butyric acid): availability, prevalence of use, desired effects and acute toxicity. Drug and Alcohol Review. 2016;35(5):591–596. doi:10.1111/dar.12356. PMID 26693960
Phenibut: a recreational drug with abuse potential. National Capital Poison Center (Poison Control). n.d.. poison.org
Esposito CM, Mandolini GM, Delvecchio G, Fiorentini A, Brambilla P. Psychomotor agitation non-responsive to treatment: a case report of phenibut withdrawal syndrome. Frontiers in Psychiatry. 2021;12:688147. doi:10.3389/fpsyt.2021.688147. PMID 34262493
Joshi YB, Friend SF, Jimenez B, Steiger LR. Dissociative intoxication and prolonged withdrawal associated with phenibut: a case report. Journal of Clinical Psychopharmacology. 2017;37(4):478–480. doi:10.1097/JCP.0000000000000731. PMID 28614159
Zheng KH, Khan A, Espiridion ED. Phenibut addiction in a patient with substance use disorder. Cureus. 2019;11(7):e5230. doi:10.7759/cureus.5230. PMID 31565631
Nedzlek CD, Michaelis A. An unusual presentation of an uncommon drug: a case report on phenibut overdose. Cureus. 2022;14(4):e23913. doi:10.7759/cureus.23913. PMID 35530906
Feldman R, Autry B, Dukes J, Lofy T, Marchetti G, Patt A, Batterman N, Theobald J. A systematic review of phenibut withdrawal focusing on complications, therapeutic approaches, and single substance versus polysubstance withdrawal. Clinical Toxicology. 2023;61(11):941–951. doi:10.1080/15563650.2023.2285702. PMID 38112312
Bonnet U, Scherbaum N, Schaper A, Soyka M. Phenibut — an illegal food supplement with psychotropic effects and health risks. Deutsches Ärzteblatt International. 2024;121(7):222–227. doi:10.3238/arztebl.m2024.0003. PMID 38377332
House Bill 2 (enrolled), amending Ala. Code § 20-2-25 to add phenibut to Schedule II. Alabama Legislature, 2021 Regular Session. 2021. Enrolled act (PDF)
Fla. Stat. § 893.03, Standards and schedules. The Florida Senate, 2024 Florida Statutes. 2024. flsenate.gov
Iowa Code ch. 124, Controlled Substances (schedules I–V). Iowa Legislature. 2025. legis.iowa.gov
Ohio Admin. Code 4729:9-1-01 through 4729:9-1-05, controlled substance schedules I–V. Ohio Board of Pharmacy, via codes.ohio.gov. 2026. codes.ohio.gov
List of Controlled Substances for the State of Arkansas (effective 3 July 2025). Arkansas Department of Health, Division of Pharmacy Services and Drug Control. 2025. healthy.arkansas.gov (PDF)

Provenance

Published: March 22, 2025
Last reviewed: September 8, 2026
Clinical review: None. This content is compiled from the cited public sources and has not undergone independent clinical review.

Cite this page

Poison Phenibut. "Phenibut: the evidence base." https://poisonphenibut.com/ (last reviewed September 8, 2026).

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