1963, St.Petersburg, Russia – A Soviet Union lab scientist by the name of Perekalin synthesizes 3-phenyl-4-aminobutyric acid, an experimental drug intended to calm psychiatric children.
1964 – Professor Khaunma labels the drug Phenigamma and reports the first findings of its tranquilizing effects in the Byulleten Eksperimental’noi Biologii i Meditsiny.
1975 – Phenigamma has spread from clinical practice to public use under the name of Phenibut. The Soviet Ministry mandates its use for astronauts in space flights due to the drug’s revolutionary psychologically calming yet cognitively stimulating effects.
2001 – Over 300 scientific publications have studied Phenibut’s nootropic and pharmacological properties.
2014 – Phenibut is used all over the globe as a smart drug, mood enhancer, sleep aid and recovery booster.
Wait, why is a meathead writing about a smart drug?
Because bodybuilding is driven by more than improving your physique. It is a lifestyle of self-improvement. The Ancient Greeks were known for their philosophy that education should encompass physical as well as mental training. The Romans knew it. There was little distinction between education and physical training in the Renaissance and the Age of Enlightenment, but today most people don’t even realize that ‘gym’ stands for gymnasium and bodybuilding has turned from educational virtue to intellectual vice.
Phenibut is a derivative of GABA (gamma-aminobutyric acid). GABA is the primary neurotransmitter in your body that regulates the neuronal excitability of the central nervous system. Basically, GABA makes sure that your brain does not become hyperactive.
Why not just supplement with GABA directly then? Phenibut crosses the blood-brain barrier more effectively than GABA itself in supplement form. GABA is naturally produced in the brain itself, therefore it normally does not need to cross the blood-brain barrier to be effective .
In humans, Phenibut supplementation causes 2 main effects by acting on your nervous system [2, 3, 4].
- It is a nootropic (smart drug). Phenibut primarily increases motivation, attention and concentration with a weaker effect on memory and little effect on overall intelligence.
- It is a strong anxiolytic (anxiety killer). Phenibut is used to treat panic attacks, stuttering, Parkinson’s disease, neuroses, vestibular (balance) disorders, spasticity, epilepsy, hyperactivity, insomnia and post-traumatic stress disorder. Pick-up artists use Phenibut to shake the nerves of cold-approaching beautiful women.
Anecdotally, Phenibut also improves sleep quality. We know GABA supplementation does , so it’s plausible Phenibut does too, being a GABA-derivative that more effectively crosses the blood-brain barrier.
In addition, Phenibut has mood enhancing effects. It has thymoleptic (anti-depressant) properties and can reduce irritability and fatigue. It is clinically used to treat asthenic-depressive syndrome. 
These psychoactive effects are similar in mechanism to alcohol but without the depressant effects. In the upper/downer classification of drugs, alcohol is a downer, but Phenibut is neither. Phenibut gives you focus and calmth without the jitters of caffeine or the cloudiness of alcohol.
Phenibut’s effects can easily last the rest of the day, even though Phenibut’s plasma half-life is only 5.3 hours . This is because Phenibut’s action on the GABA receptors can linger long after your kidneys have excreted all the Phenibut [16, 17].
Not just for astronauts
Phenibut has a few more effects that are particularly relevant for bodybuilders.
- Phenibut can increase resting and post-exercise growth hormone secretion. In a study of weight training men, GABA supplementation increased resting growth hormone concentrations by 375%. Post-exercise growth hormone concentration rose by 175%. Baclofen, which works almost exactly the same as Phenibut, also increases growth hormone synthesis. [5, 6, 7, 8]
- Phenibut is anti-hypoxic. When you train a muscle intensely, it can’t get enough oxygen anymore and become hypoxic. This metabolic stress mediates muscle hypertrophy. Phenibut may thus increase your tolerance to metabolic stress and allow you to train harder. 
- Phenibut is neuroprotective and augments cell energy potential, again possibly allowing you to train harder. 
One study also found that Phenibut increased muscle strength, but this finding is likely limited to neurotic and psychotic individuals, because the above study in resistance trained males did not find an increase in weight lifted [5, 6, 9]. You shouldn’t think of Phenibut as a typical ergogenic or performance enhancer anyway. In fact, as I’ll discuss in the dosage section below, excessive Phenibut intake can decrease your performance. Rather, think of Phenibut as a recovery enhancer and don’t expect miracles from it.
In my experience, Phenibut works best in very lean individuals. Phenibut can counteract the natural decrease in growth hormone production associated with being lean. This may help your joints stay healthy and keep your metabolism high. Phenibut’s mood enhancing effects are also very beneficial here, as anyone who’s ever been below 7% body fat will be able to tell you.
The optimal Phenibut dosage
The vast majority of studies have only researched dosages up to 3 grams a day. At these dosages, no psychological side effects are found [2, 10]. However, many people take much higher dosages for longer periods of time. This is the same more is better fallacy that leads people to drastically overestimate how much protein they need per day and become addicted to caffeine. Like caffeine, Phenibut feels great and seems harmless, so people consume high amounts of it on a regular basis. The result is addiction: tolerance to the good effects and withdrawal when ceasing supplementation. And they pay the price. Phenibut withdrawal is hell. When coming off 20 grams a day, you can literally become psychotic for a while . Tapering off the dose will minimize withdrawal symptoms, but my recommendation is to avoid becoming addicted in the first place.
To find the optimal Phenibut dosage, we have to look at the extensive research on animals and calculate the human equivalent dose by correcting for the interspecies difference in metabolism. Since it’s very technical, I’ve created a Phenibut dosage calculator that does the math for you.
For those interested in the math, here’s how I’ve done the calculations.
- Your Body Surface Area (m²) = 0.007331 x Height (cm)0.725 x Weight (kg)0.425 [11, 12]
It’s important to calculate your BSA and not use 1.6 as a default, because this will lead to an underestimation in bodybuilders and an overdose in lean women.
- Your Km factor = Weight (kg) / body surface area (m2) 
- Multiply the animal dosage by the animal’s Km factor divided by your own Km factor to get the human equivalent dose .
- Calculate the HED for 70 mg/kg in mice for the maximum pre-workout/side effects dosage threshold and use 200 for the addiction threshold.
Using 3 grams of Phenibut a day consistently results in a strong tolerance to Phenibut’s effects and withdrawal when no longer taking the drug [2, 17]. Addiction takes less than 10 days to develop [16, 17]. A 5’10” (1.78 m) adult weighing 176 lb (80 kg) will develop a tolerance to using 1.2 grams of Phenibut a day . It is unfortunately not known how low the Phenibut dose has to be not to result in addiction, so it’s best to err on the side of safety.
Phenibut is better taken after than before your workouts. Based on the above stats, just 0.4 gram of Phenibut decreases motor cortex activity, muscle tone, coordination and body temperature. I already explained how these factors contribute to the best time to work out, but the short version is simply that too much pre-workout phenibut is bad for your performance.
Phenibut can be a wonderful drug, but it is not to be trifled with. In short, don’t be an idiot. This may seem like common sense, but “if sense were common, everyone would have it”. In fact, it bears repeating. Don’t be an idiot. Use the above formulas to calculate the best Phenibut dosage for your goal. Limit your pre-workout dosage to a maximum of ~0.5 gram, your daily dosage to ~1 gram and never consume more than ~3 grams unless you know exactly what you’re doing.
Perhaps most importantly, Phenibut’s effects are highly mediated by stress and anxiety. So your personality type and the situation strongly determine how much benefit you will experience from Phenibut. If you are not in a stressful or social situation and you have a naturally calm personality, you may not feel anything from Phenibut unless you take several grams. So experimentation and timing is everything to find the dosage that works for you. It’s a drug, not some supplement you take daily just to take it.
Phenibut is a legal drug/supplement in practically every country except Australia and is generally available over the counter. This is another reason why people underestimate it. There is almost no relation between the legal status and the safety of drugs (don’t be naive!). Phenibut is one of those drugs that fortunately seems to have slipped through the (many) cracks of legislation, but this won’t be for long if more idiots start mega-dosing the stuff and the media gets a hold of someone hallucinating in a McDonald’s pointing at fat people and hysterically shouting at the manager “It’s alive!”
Anyway, Phenibut can be tricky to obtain despite it being legal. Most supplement stores and Amazon don’t carry it anymore. Enter my secret supplement buying method: eBay. Don’t bother with the auctions. Just find a top rated seller for ‘Buy it now’.
- Phenibut is a smart drug, mood enhancer, sleep aid and recovery booster.
- You can buy it on eBay or here.
- Use the formulas in this article to calculate the maximum dose you can use without side effects or addiction.
Tip: use the Google Translate plug-in for your browser if you want to delve into the Russian literature.
1. Khaunina, R.A., Maslova, M.N., 1968. The pharmacologic activity and cerebral
permeability of gamma-aminobutyric acid and its derivatives. Rus. Vopr.
Psikhiatr. Nevropatol. 13, 583-591.
2. Phenibut (beta-phenyl-GABA): a tranquilizer and nootropic drug. Lapin I. CNS Drug Rev. 2001 Winter;7(4):471-81.
3. Sytinsky, I.A., Soldatenkov, A.T., 1978. Neurochemical basis of the therapeutic
effect of gamma-aminobutyric acid and its derivatives. Prog. Neurobiol. 10,
4. Neumyvakin, I.P., Krupina, T.N., Polevoi, L.G., Semeikina, L.A., 1978. Principles for making up pharmaceutical kits to supply cosmonauts with drug packs. In Rus. Kosm. Biol. Aviakosm. Med. 12, 27-31.
5. GABA Supplementation and Growth Hormone Response. Powers M. Lamprecht M (ed): Acute Topics in Sport Nutrition. Med Sport Sci. Basel, Karger, 2012, vol 59, pp 36-46
6. Powers, M. E., Yarrow, J. F., McCoy, S. C., & Borst, S. E. (2008). Growth hormone isoform responses to GABA ingestion at rest and after exercise. Medicine and science in sports and exercise, 40(1), 104.
7. Cavagnini F, Benetti G, Invitti C, et al. Effect of gamma-aminobutyric acid on growth hormone and prolactin secretion in man: influence of pimozide and domperidone. J Clin Endocrinol Metab. 1980;51:789-92.
8. Cavagnini F, Invitti C, Pinto M, et al. Effect of acute and repeated administration of gamma aminobutyric acid (GABA) on growth hormone and prolactin secretion in man. Acta Endocrinol (Copenh). 1980;93:149-54.
9. Mehilane LS, Rago LK, Allikmets LH. Pharmacology and clinic of phenibut. Tartu: Izd. TGU, 1990
10. Lapin IP, Khaunina RA. Pharmacology and clinical use of gamma-aminobutyric acid and its derivatives. In: Role of gamma-aminobutyric acid in the activity of the nervous system. Leningrad: Izd. LGU, 1964:101-115
11. Determination of body surface area and formulas to estimate body surface area using the alginate method. Lee JY, Choi JW, Kim H. J Physiol Anthropol. 2008 Mar;27(2):71-82.
12. Body surface area in normal-weight, overweight, and obese adults. A comparison study. Verbraecken J, Van de Heyning P, De Backer W, Van Gaal L. Metabolism. 2006 Apr;55(4):515-24.
13. Hogberg, L., Szabo, I., & Ruusa, J. (2013). Psychotic symptoms during phenibut (beta-phenyl-gamma-aminobutyric acid) withdrawal. Journal of Substance Use, (00), 1-4.
14. Dose translation from animal to human studies revisited. Reagan-Shaw S, Nihal M, Ahmad N. FASEB J. 2008 Mar;22(3):659-61.
15. Adapted from Dave Asprey.
16. Effect of multiple daily administration of fenibut and diazepam on GABA and benzodiazepine receptors in the mouse brain. Riago LK, Sarv KhA, Allikmets LKh. Biull Eksp Biol Med. 1983 Dec;96(12):49-50.
17. Peripheral mechanism of the phenomenon of fenibut habituation. Gusel VA, Smirnov DP. Farmakol Toksikol. 1980 Jul-Aug;43(4):431-3.
18. Effect of oral ?-aminobutyric acid (GABA) administration on sleep and its absorption in humans. Yamatsu A, Yamashita Y, Pandharipande T, Maru I, Kim M. Food Sci Biotechnol. 2016 Apr 30;25(2):547-551. doi: 10.1007/s10068-016-0076-9
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