Phenibut is beta-phenyl-GABA, a GABA-B agonist developed in the Soviet Union in the 1960s and still prescribed in Russia and the Baltic states.
Amounts reported for Phenibut HCl are listed under Reported protocols, each with its source and study kind. No amount ladder is inferred from them. This is educational source context, not a protocol or recommendation.
Enter a target amount only from your own reviewed source. The calculator can convert it into concentration, volume and device markings, but it will not infer an amount from product availability or another compound.
Only mcg or mg amounts are retained. The calculator derives mL, syringe units or pen clicks from the current vial strength, water volume and device.
Human study rows are described per source under Reported protocols; they belong to their trial populations and are not a general amount.
Verify the exact compound, formulation and amount against the product label or certificate before calculation.
Follow the product label, certificate and validated laboratory SOP; no universal storage assumption is applied here.
Label concentration and preparation date, use sterile technique where applicable, and follow a validated stability protocol.
What published studies and recent community write-ups report about amounts, timing and course length. 6 clinical and 3 community-reported rows, each linked to its source. These are descriptions of what others report, not instructions, and nothing here is medical advice.
| Context | Dose | Frequency | Route | Course | Source |
|---|---|---|---|---|---|
| Clinical6 rows | |||||
| Registered Latvian product in adjustment disorder (observational study)90 adults aged 18-70 with adjustment disorder in Latvian general practice | 250 mg | Three times daily (750 mg per day) | Oral capsules (Noofen) | At least 3 weeks, per routine practiceNone described | Journal of Clinical Medicine (PubMed)2025 |
| ADNM-20 scores fell by a mean of 14.8 points after three weeks, with the largest changes in sleep disturbance, restlessness and anxiety, and the drug was described as well tolerated. The study was non-interventional and uncontrolled, in a country where phenibut is a licensed prescription medicine, so it reflects routine therapeutic use rather than proof of efficacy. | |||||
| Pharmacology and toxicology review of human useReview of human pharmacokinetic, clinical and poisoning literature | 250 mg single dose in pharmacokinetic volunteers; 250-500 mg per day in later clinical reports; Russian fact sheets cap daily intake at 2500 mg | Daily in therapeutic use | Oral | Not specifiedNot specified | Basic and Clinical Pharmacology and Toxicology (Wiley)2024 |
| After a single 250 mg oral dose about 65 percent was excreted unchanged in urine with a plasma half-life of 5.3 hours, and only about 0.1 percent of a dose is thought to reach the brain. The review documents severe withdrawal, including a month-long intake of up to 5000 mg a day that produced a withdrawal syndrome resistant to diazepam, haloperidol and baclofen for weeks, and notes that online products have quietly lowered their printed daily maximum from 2000 mg to 1000 mg. | |||||
| German clinical review of phenibut as an illegal food supplementReview of pharmacology, intoxication and withdrawal reports | Therapeutic daily doses of 250-2000 mg in former Soviet countries; Russian taper schedules start at 500 mg once or twice in 24 hours | Daily | Oral | Not specifiedGradual step-down described for dependent users | Deutsches Arzteblatt International (PubMed Central)2024 |
| The review tabulates a 3-4 hour onset, about 65 percent urinary excretion and a 5-6 hour half-life, lists indications in the former Soviet Union from anxiety and insomnia to alcohol withdrawal, and describes baclofen 10 mg every 8 hours and, if needed, benzodiazepines for phenibut withdrawal. It classes phenibut as an illegal food supplement in Germany. | |||||
| Systematic review of withdrawal case reports25 published cases of phenibut withdrawal, all male, median age 30 | Median 10 g per day before withdrawal (interquartile range 4.75-21.5 g; range 1-200 g); the shortest use before withdrawal was one week at 2-3 g per day | Daily | Oral | From one week to prolonged useWithdrawal began as soon as two hours after the last dose | Clinical Toxicology (PubMed)2023 |
| Seizures occurred in 8 percent of cases, intubation in 24 percent and intensive care admission in 44 percent, and every case of abrupt cessation was managed as an inpatient, most often with benzodiazepines plus baclofen. A separate 2024 review of 15 cases put the average intake at 13.6 g a day (range 1.5-28.5 g). These are self-reported amounts of unregulated product, so the true doses are uncertain. | |||||
| US poison centre surveillance1,320 phenibut exposure calls to US poison centres, January 2009 to December 2019, mean age 31.7, 75.5 percent male | Not recorded per case; 65.1 percent of exposures with a known form involved tablets and 24.8 percent powder | Not applicable | 93.2 percent ingestion | Not applicableNot applicable | Morbidity and Mortality Weekly Report, CDC2020 |
| Calls rose sharply after 2015, 85 percent came from health care facilities, 12.6 percent of exposures had major life-threatening effects and three deaths were reported; among phenibut-only exposures 10.2 percent had major effects including one death. The CDC note records that the FDA has ruled phenibut is not a dietary ingredient and cannot be listed in supplements, although possession is legal. | |||||
| Supplement market analysis10 over-the-counter cognitive enhancement products bought online in the United States | Up to 15.4 mg of undeclared phenibut per serving; the paper quotes 250-500 mg as the typical pharmacologic dose | As labelled | Oral | Not applicableNot applicable | Neurology: Clinical Practice (PubMed)2021 |
| Phenibut was one of three unapproved drugs found in products that did not declare it, alongside vinpocetine and picamilon. The amounts were small, but the paper shows that phenibut turns up in products a buyer would not expect to contain it. | |||||
| Community-reported3 rows | |||||
| Harm-reduction dosing guide | 250 mg first test dose; 500-750 mg as a situational dose; 500-1000 mg described as the intermediate range | No more than once a week for beginners; at most twice a week with 72 hours between doses and no more than 6 days in any 30 | Oral, with food, taken 2-4 hours before the event | Occasional use only; many users described as taking it 4-6 times a yearMinimum 3-7 day gaps; a 10-15 percent reduction every 3-7 days is described for anyone who has been dosing daily | Community resource2026 |
| This 2026 guide treats frequency, not dose, as the main driver of dependence, warns that redosing during the 2-4 hour onset is how most over-sedation happens, and lists alcohol, benzodiazepines, opioids and baclofen use as absolute contraindications. It describes withdrawal after as little as 2-4 weeks of daily use at 1 g a day or more and tells readers never to stop abruptly. These are community harm-reduction limits, not studied regimens. | |||||
| Supplement reference site dose table | 250-750 mg per day for occasional use, in 1-2 doses; 250-500 mg suggested for a first trial | No more than 1-2 times a week with at least 3-4 days between doses | Oral, taken 2-3 hours before the situation it is meant for | If used regularly, 1 week on (1-2 doses) followed by at least 2-3 weeks offGradual taper rather than abrupt stopping after any regular use | Community resource2024 |
| Updated November 2024, this page frames every use as occasional, warns that the slow onset leads people to take a second dose before the first has worked, and advises against daily use as a sleep aid because of tolerance and dependence. Its frequency limits match other community guides and have not been studied. | |||||
| Vendor research-use listing | 250 mg per capsule, 60 capsules per bottle | Not stated (sold for laboratory research only) | Oral capsule format | Not statedNot stated | Community resource2026 |
| Vendor claim. The vendor sells phenibut HCl as 250 mg capsules, the same strength as the Latvian prescription product, with a third-party LC-MS identity report for lot PB01 and no purity verdict. The page cites the Lapin review and a withdrawal case report, gives no dosing information and states the product is not for human consumption. | |||||
Community guides describe a 250 mg test dose and a wait of 3-4 hours before judging it, because effects build slowly and the slow onset is what leads people to take a second dose that lands on top of the first.
The pattern described is occasional, situational use at 500-750 mg no more than once or twice a week with at least 72 hours between doses, on the stated grounds that frequency rather than dose drives dependence. Daily use is described as the path to withdrawal within weeks.
The licensed pattern in Latvia is 250 mg three times a day for a course of at least three weeks, which is a daily regimen the community guides specifically avoid. Published withdrawal cases involved far larger daily amounts, median 10 g, and were treated in hospital.
Plus 3 community resources (dosing guides, forum threads and vendor write-ups), reported above but not linked.
Phenibut is beta-phenyl-GABA, a GABA-B agonist developed in the Soviet Union in the 1960s and still prescribed in Russia and the Baltic states. It is sold there under names such as Noofen for anxiety, sleep and asthenic complaints, and the licensed Latvian product is a 250 mg capsule taken three times a day. In the United States it is unapproved, cannot legally be sold as a dietary supplement, and poison centres logged 1,320 exposures between 2009 and 2019 with three deaths, while published withdrawal cases involve daily intakes with a median around 10 g. This page uses the hydrochloride salt record because that is what vendors sell; the free base is a separate PubChem entry.
These themes describe recurring questions in published research. They are not claims of effectiveness or recommendations for use.
Neuroplasticity, cognition, stress and sleep models.
ADNM-20 scores fell by a mean of 14.8 points after three weeks, with the largest changes in sleep disturbance, restlessness and anxiety, and the drug was described as well tolerated. The study was non-interventional.
After a single 250 mg oral dose about 65 percent was excreted unchanged in urine with a plasma half-life of 5.3 hours, and only about 0.1 percent of a dose is thought to reach the brain. The review documents severe.
The review tabulates a 3-4 hour onset, about 65 percent urinary excretion and a 5-6 hour half-life, lists indications in the former Soviet Union from anxiety and insomnia to alcohol withdrawal, and describes baclofen.
Seizures occurred in 8 percent of cases, intubation in 24 percent and intensive care admission in 44 percent, and every case of abrupt cessation was managed as an inpatient, most often with benzodiazepines plus.
Calls rose sharply after 2015, 85 percent came from health care facilities, 12.6 percent of exposures had major life-threatening effects and three deaths were reported; among phenibut-only exposures 10.2 percent had.
Study models remain visible so laboratory and animal findings are not mistaken for established human outcomes.
6 protocol rows on this page come from human trials, trial registrations, regulator labels or reviews of human data. Approval status and populations are stated per row.
3 rows record what blogs, vendor write-ups or forums describe for Phenibut HCl. None has been verified against primary literature.
Sequence, synonyms and registry identifiers as recorded in PubChem, the National Library of Medicine's open chemistry database. Formula, mass and CAS number are summarized at the top of the page.
Phenibut hydrochloride, 4-Amino-3-phenylbutyric acid hydrochloride, beta-Phenyl-GABA hydrochloride, gamma-Amino-beta-phenylbutyric acid hydrochloride, Phenibut (hydrochloride), 4-Amino-3-phenylbutyric acid HCl, UNII 625240H2LN, Baclofen Impurity 34 Hydrochloride
XSYRYMGYPBGOPS-UHFFFAOYSA-N
4-amino-3-phenylbutanoic acid;hydrochloride
8 curated references, each with its journal, year and study model, plus 3 community resources reported but not linked.