How Long Does Phenibut Last? | What You MUST Know

Wondering how long does Phenibut last? You’ve come to the right place.

I am not going to lie…

I love Phenibut. I love that it’s easy to get, it’s cheap, it’s legal, and it makes me feel great. I am more sociable at parties, I can think more clearly when I’m awake, and I sleep better at night. Best of all, I get a nice little mood boost. Phenibut makes me feel like I can take on the world.

Here’s another nice little side effect of taking Phenibut: it lasts for a long time.

Like, sometimes I feel the great effects the next day, more than 24 hours after I take it. The long-lasting effects of Phenibut are one of the reasons that so many people like it. You get a lot of bang for your buck.

But exactly how long does it last? How long does it take for Phenibut to kick in? When and how should you take it? And what Phenibut dosage is ideal?

P.S: Click here to order Phenibut from the top vendor online!

These answers can be a bit confusing for newbies, so I want to get it all down here. Welcome to the #1 guide on how long does Phenibut last.

P.S: It should come as no surprise that I’m not a doctor or a lawyer. This is not legal or medical advice. The information presented on this site is purely entertainment. Always consult a medical professional before consuming any nootropics. Full disclaimer.

What is Phenibut?

First, though, what is Phenibut?

Phenibut is basically a protein that mimics one of the neurotransmitters in your brain [1].

“Phenibut” is a shortened version of its chemical name: Aminophenylbutyric acid. It’s chemical structure closely resembles that of the neurotransmitter “GABA”. That means that Pehnibut can bind to some of the same receptors as GABA and have some of the same effects [1].

GABA plays an important role in reducing the excitability of neurons and inhibiting them. Think of it like a neuron is a light switch. Other neurotransmitters help turn on the light; GABA (and Phenibut) turn off the light [1].

That means that they both play a role in relaxing the brain and get it to chill out. Phenibut is an effective anti-anxiety medication prescribed in several countries around the world. It’s also used to treat a number of other conditions like sleep disorders, vestibular disorders, tics, and stuttering.

Some people also use it recreationally as well. Users say it’s great for reducing social anxiety at parties. It’s a bit like alcohol in that the users feel less inhibited, but you don’t get the foggy brain that alcohol gives you, and it doesn’t affect your memory. In fact, Phenibut actually gives users a cognitive enhancement at low doses, which is why it’s considered a nootropic [1].

Because it also gives a boost in dopamine at low doses, it also provides a bit of a euphoric feeling or “high”. Again, that’s why people love it for parties [2, 3].

Phenibut dosage

Phenibut Side Effects and Safety

Okay, but is it safe? I actually have a whole article on Phenibut side effects and safety, but I’ll summarize it here.

Basically, yes [1].

Phenibut considered safe for use by most people. That’s why it’s been used as a medication for almost 40 years in countries like Russia, Ukraine, and Belarus [1].

However, there are some things you have to be cautious about, just like anything. There are some rare but occasional side effects; there’s a possibility of an allergic reaction; there are some substances you shouldn’t mix it with; and you have to be careful about dependence [3, 4, 5].

Side Effects

Again, side effects are rare, but they occur. Side effects include [4, 5]:

  • Drowsiness
  • Nausea
  • Irritability
  • Headache
  • Sedation

Also, while also rare, be aware of the potential of allergies. Allergic reactions to Phenibut can include itchiness and rashes.

Interaction Effects

Phenibut has a similar effect to a bunch of other substances that also affect GABA and GABA receptors. That means you should avoid mixing them. Taking two different substances that affect the same neuron pathways can amplify the effect or make it last longer [6].

Try to avoid taking Phenibut at the same time as:

  • Alcohol
  • Benzodiazepines
  • Anticonvulsant medications
  • Opioids
  • Anti-psychotics
  • Sedatives

Avoiding mixing Phenibut with these will help avoid any unpleasant interaction effects.

Dependence and Withdrawal

Again, like any substance, there’s a risk of dependence. If you use it properly, most users never have problems with this.

But you should be aware of it, so that you continue to use it properly [4, 5].

Since it can have such great effects, you have to make sure to be careful about not overusing it.

Our guide on Phenibut withdrawl talks about this in more depth, but, very briefly, dependence happens when you take

Phenibut so often that your body stops making your own GABA because those receptors are used to getting stimulated by Phenibut. That’s dependence.

Withdrawal happens when you stop taking it all of a sudden and your body is used to it. Since your body isn’t making much of its own GABA anymore, and since you stopped Phenibut, there isn’t anything to stimulate those receptors. You start to experience physical symptoms that can be really unpleasant.

Withdrawal symptoms can include [4, 5]:

  • Rebound anxiety
  • Anger
  • Agitation
  • Irritability
  • Insomnia
  • Auditory and visual hallucinations
  • And even psychosis

Avoiding Negative Effects

How do you avoid these negative effects and use Phenibut safely?

It’s not hard. Don’t use it too much, don’t use it too often, and don’t mix it:

  • Don’t take more than 1 gram at a time
  • Don’t take more than 2 grams a day
  • Don’t take more than 2 times a week
  • Don’t take it if you’re allergic
  • Don’t take it with alcohol, Benzos, opioids, or other depressants
  • Don’t take it if you have an addictive personality

Easy, peazy. Now to the good stuff…

How long does Phenibut last?

How Long Does Phenibut Last? | A-Z Guide

Phenibut lasts a long time. But how long it lasts depends on a few things:

  • Your size
  • Your age
  • How large your Phenibut dosage is

If you’re younger, larger, or you take a smaller dose, it will not last as long. If you’re older, smaller, or you take a larger dose, it will last longer. Keep that in mind when you’re reading these guidelines.

In general, users can expect Phenibut’s “high” to last between 2 to 5 hours after it kicks in and begins to work.

After 5 hours, you’ll notice that any “high” you felt will start to recede.

But even after that time, there’s still enough in the body to have residual effects that may not be a “high” but can still be powerful for people. These residual effects of lowered anxiety, boosted mood, and good sleeping can last up to 24 hours after taking it.

Remember, the effects are long-lasting, but they’re not like alcohol where you can’t think properly. You have a clear mind with Phenibut. Especially at low levels, Phenibut can help increase concentration. At higher levels, it can sometimes make you feel a bit drowsy.

And again, it all depends on your own individual chemistry and the size of the dose that you took.

Phenibut HCL

Understanding the Phenibut Half-Life

One of the reasons that Phenibut lasts so long is that it has a half-life of 5 hours [3].

What is the Phenibut half-life?

A half-life is the amount of time it takes for a substance to reduce by half. The Phenibut half-life is 5 hours, which means that after 5 hours, the concentration of Phenibut in your body will have been reduced by 50% [3].

So if you take a 500 mg dose, after 5 hours, there will still be 250 mg in your body. 5 hours later, there will still be 125 mg. And so on.

While 125 mg is not enough for you to really feel a direct effect, you still might feel the residual good effects.

Which is why you can often feel Phenibut working 10 hours or even 20 hours after you take it.

How Long Does It Take For Phenibut to Kick In?

Phenibut is generally slow to kick in. Most users report that it takes about 2 hours to really kick in.

Again, though, it depends a bit on how you take it.

So essentially, you’ll take Phenibut and then wait two hours. The nootropic will kick in, and then you’ll have 3-4 hours of truly feeling it — before things start to wear off.

For example, if you buy Phenibut FAA and you take it sublingually (so it absorbs into your blood through the skin under the tongue), it kicks in much faster: in about 30 minutes. If you’re taking capsules or mixing it in a drink, 2 hours is generally how long it will take to kick in.

Keep in mind that the effects are subtle until it’s kicked in.

If you’re expecting a “high” like you get from other harder drugs, you might not think it’s working at all. But it is, it’s just a subtle feeling of boosted mood and less anxiety.

You basically feel like you’ve drank 3-6 beers for the next 3-4 hours, once the Phenibut kicks in.

To really notice the effects, trying going into a social situation, doing some work, or going to a party. Sometimes changing the environment can help you really see the effects.

Phenibut Dosing and Half-Life

You can plan your Phenibut dosage based on how long they want the effects to last for [3, 7, 8].

For example, taking 1 gram of Phenibut will leave you with 500mg still in your body after 5 hours, 250mg after 10 hours, and 125mg after 15 hours. So you can expect some residual effects to last up to almost 20 hours. Maybe even longer.

If instead, you start with a microdose of 50mg, you probably won’t feel a huge effect [7]. You’ll be less anxious, maybe have a bit better mood, and perhaps you’ll have more concentration… but you won’t feel a huge change.

You also won’t have the effects last as long; they’ll probably all be gone within a few hours.

So keep that in mind when an individual chooses their Phenibut dosing plan: their dose will affect how long they’ll notice effects for.

I suggest that all “test subjects” start with a low dose if they’re beginning. You want to see how it affects your body before committing to a high dose.

Buy Phenibut Online | 2020 Guide

Phenibut is not approved as a psychoactive drug in most places. So you generally can’t find it in pharmacies or drug stores.

But because it’s a protein, it’s available in almost all countries as a diet supplement. That means it’s easily available online, and it’s legal to buy almost everywhere

Exceptions are Australia, Lithuania, and Hungary… it’s banned in these countries. See our guide on Phenibut legalities for more information.

For most countries, it’s easily and legally purchased online.

But you still need to be careful: some websites are scams. Make sure if you buy Phenibut online that you do so from a legitimate place.

I’ve done a bit of trial and error, so I am comfortable recommending my source. They’re professional, they ship anywhere, and their prices are super reasonable.

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Phenibut Half-Life | The Verdict

How long does Phenibut last?

A long time. Hours. Some users report that it can last up to 24 hours.

That’s because of its long half-life: it takes 5 hours for half of the substance to be metabolized.

That’s good news for users. I’ve taken it in the afternoon about 2 hours after eating lunch and 2 hours before dinner.

Then it kicks in at about dinner time or just after. I go to a party and I feel really great and sociable. I don’t have to drink to have a good time, which leaves me feeling clear-headed and healthy (as I mentioned, don’t mix this with alcohol, it can have more intense interaction effects that way). Then when I get home, I can get a great night’s sleep and even go workout the next day.

I really feel like Phenibut could make a huge difference in a lot of lives.


  1. Lapin I. (2001). Phenibut (beta-phenyl-GABA): a tranquilizer and nootropic drug. CNS drug reviews, 7(4), 471–481. doi:10.1111/j.1527-3458.2001.tb00211.x
  2. Cheung, J. & Penn, J. (2018). Weekly dose: Phenibut. The Conversation.
  3. Owen, D. R., Wood, D. M., Archer, J. R., & Dargan, P. I. (2016). Phenibut (4‐amino‐3‐phenyl‐butyric acid): Availability, prevalence of use, desired effects and acute toxicity. Drug and alcohol review, 35(5), 591-596.
  4. Ahuja, T., Mgbako, O., Katzman, C., & Grossman, A. (2018). Phenibut (β-Phenyl-γ-aminobutyric Acid) Dependence and Management of Withdrawal: Emerging Nootropics of Abuse. Case reports in psychiatry, 2018. doi:10.1155/2018/9864285
  5. Högberg, L., Szabó, I., & Ruusa, J. (2013). Psychotic symptoms during phenibut (beta-phenyl-gamma-aminobutyric acid) withdrawal. Journal of Substance Use, 18(4), 335-338.
  6. Ozon Pharm (n.d.), Fenibut (PDF). [In Russian].
  7. Zheng, K. H., Khan, A., & Espiridion, E. D. (2019). Phenibut Addiction in a Patient with Substance Use Disorder. Cureus, 11(7).
  8. Hardman, M. I., Sprung, J., & Weingarten, T. N. (2019). Acute phenibut withdrawal: A comprehensive literature review and illustrative case report. Bosnian Journal of Basic Medical Sciences, 19(2), 125.


After utilizing nootropics for the better part of a decade, I realized the potent results these products produce -- with regards to productivity and cognitive enhancement. Soon thereafter, I became obsessed with finding the premier smart drugs on the market. Then using them to improve my life. When I'm not devouring everything I can about nootropics and the science behind why they work, you'll find me traveling around the world or in the gym.

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