Phenibut, a popular anxiolytic and nootropic supplement, has gained attention for its potential to reduce anxiety and improve sleep quality.

In this article, we will explore the duration of phenibut's effects, how to make it last longer, and which nootropic supplements can be combined with it to prolong benefits. We will also address common questions regarding phenibut's presence in the system, long-term effects, and potential to cause drowsiness.

See The Best Nootropics For Anxiety

Using nootropic supplements can dramatically reduce stress and anxiety levels on a day-to-day basis. The right nootropics can even help control acute anxiety attacks and help keep you calm, focused and mentally clear during periods of peak stress at work. The trick is to find the anti-anxiety nootropics that actually work. See our current rankings of the best nootropics for anxiety now!

Duration of Phenibut Effects

Phenibut's effects typically begin 2 to 4 hours after ingestion and can last anywhere from 15 to 24 hours, depending on the dosage and individual factors. The long duration of action is attributed to phenibut's slow absorption rate and half-life of approximately 5.3 hours.

Phenibut anxiety nootropic

Factors Affecting Phenibut Effect Duration

There are several factors that can affect how long Phenibut lasts. The most important of these factors are:

  1. Dosage: Higher doses of phenibut tend to have longer-lasting effects.

  2. Individual physiology: Metabolic rate, body weight, and genetics can influence how long phenibut lasts in a person's system.

  3. Tolerance: Regular users may develop tolerance, leading to reduced duration and effectiveness.

It should not be surprising if you find that how long Phenibut lasts differs considerably user to user; the above three variables can have a significant effect on both the intensity and duration of action.

So what can you do if you are looking to make Phenibut last longer?

Prolonging Phenibut's Effects

While the long-lasting effects of phenibut are generally sufficient for most users, there are some strategies to prolong its benefits:

  1. Take phenibut with a meal: Consuming phenibut with food may slow down its absorption rate, prolonging its effects. However, it may also delay the onset of its effects.

  2. Divide the dosage: Dividing the daily dosage into smaller doses taken throughout the day may help maintain consistent phenibut levels in the bloodstream, extending its effects.

  3. Use a sustained-release formulation: Sustained-release phenibut formulations can provide a steady release of the compound over an extended period, prolonging its effects.

  4. Combine with other anxiolytics: You may both potentiate and prolong the effects of Phenibut by stacking the drug with other nootropics known to reduce anxiety and help with stress control. We have listed some of these nootropics below.

There are several reasons why someone might look to prolong the effects of Phenibut. Generally speaking, taking more Phenibut is not a good way to make the drug last longer, as you will quickly develop a tolerance and get diminishing returns. Instead, try the tactics above and consult with a doctor if you begin experiencing severe or chronic anxiety.

Nootropic Supplements to Combine with Phenibut

Combining phenibut with other nootropic supplements may enhance its effects and prolong its benefits. However, it is essential to consult a healthcare professional before combining phenibut with other substances. Some nootropics to consider include:

  1. L-Theanine: This amino acid, found in green tea, promotes relaxation and stress relief without causing drowsiness. Combining L-theanine with phenibut may enhance its anxiolytic effects.

  2. Ashwagandha: This adaptogenic herb may help reduce stress, anxiety, and improve sleep quality. Combining ashwagandha with phenibut may have synergistic effects on anxiety and sleep.

  3. Bacopa Monnieri: This herb has been traditionally used to improve memory, focus, and reduce anxiety. Combining Bacopa Monnieri with phenibut may support cognitive function and prolong its anxiolytic effects.

You may also want to consider using nootropics which enhance executive cognitive function alongside Phenibut. While the primary indication of Phenibut is usually anxiety control, using it in combination with more typical performance-enhancing nootropics can pay huge dividends for those of you looking to use the drug to improve work productivity and performance.

Here are some other nootropics to consider stacking with Phenibut:

  • Citicoline: Also known as CDP-Choline, this compound is renowned for its ability to enhance cognitive function. As a precursor to the neurotransmitter acetylcholine, it can boost attention, memory, and mental energy. When used in combination with phenibut, citicoline can potentially counteract any sedative effects of phenibut, helping maintain a balanced state of mental clarity and focus.

  • Phosphatidylserine: This phospholipid plays a crucial role in maintaining cell structure and function, especially in the brain. It supports memory, learning, and attention, making it an excellent companion to phenibut for individuals seeking cognitive enhancement. In combination with phenibut, phosphatidylserine could potentially extend phenibut's cognitive benefits, ensuring a sharper and more focused mind.

  • Tyrosine: Perhaps the best-suited for stacking with phenibut, this amino acid is a precursor to crucial neurotransmitters like dopamine, norepinephrine, and adrenaline. Tyrosine is known to enhance cognitive performance, especially in stressful situations, by boosting the brain's dopamine levels. This could effectively complement phenibut's calming effects with an uplift in cognitive vitality and productivity.

When considering any nootropic stacking, it's vital to consult with a healthcare provider or a nootropics expert to ensure safe and effective use. Each individual's response to nootropics can vary, and what works best for one person may not be the same for another. Always prioritize safety and listen to your body's response when experimenting with different nootropic combinations.

How Long Does Phenibut Stay in the System?

Phenibut has a half-life of approximately 5.3 hours, which means it takes around 5.3 hours for the concentration of phenibut in the bloodstream to decrease by half. It typically takes 4 to 5 half-lives for a substance to be eliminated from the body. In the case of phenibut, it can take up to 26.5 hours to be cleared from the system.

Long-term Effects of Phenibut

As mentioned earlier, there is limited research on the long-term effects of phenibut. Prolonged use of phenibut can lead to tolerance and dependence, increasing the risk of withdrawal symptoms and potentially causing lasting effects on brain function. Some potential long-term effects of phenibut use include cognitive impairment, depression, and physical health issues, such as liver damage and gastrointestinal problems.

Top Phenibut Alternatives


#1 Rated


Xanapril is a cutting-edge natural supplement designed to dramatically decrease stress and anxiety levels without producing any kind of drowsiness or cognitive impairment in users. In fact, Xanapril has been designed in such a way as to treat stress and anxiety in multiple different ways while actually enhancing cognitive performance and improving mood. 

Nooceptin top rated nootropic stack

#2nd Rated


Nooceptin is an all-in-one nootropic designed to provide total cognitive enhancement on a daily basis. The benefits of taking Nooceptin include sharper focus, better working memory function, faster processing speeds and reduced stress & anxiety. Nooceptin also supports brian cell health, maintenance and development, making it ideal for long-term, daily use. This is the most powerful full-spectrum nootropic you can buy OTC.


#1st Rated


Vyvamind is perfect for those of you looking for an alternative to synthetic smart drugs which don't cause anxiety. While compounds like Modafinil, Vyvanse and Oxiracetam are all unarguably effective, they are all prone to causing quite serious side effects, including acute anxiety. Vyvamind was specifically developed to provide the same increases in focus, mental clarity and motivation as prescription smart drugs, but without the same side effects or long-term health risks. 

Does Phenibut Make You Sleepy?

Phenibut is known for its sedative properties and can make some users feel sleepy or drowsy, particularly at higher doses. It has been used to promote sleep and improve sleep quality in individuals with sleep disorders. However, the sedative effects of phenibut can vary depending on individual factors, such as tolerance and metabolism.

If you are concerned about the potential for drowsiness, consider starting with a lower dose of phenibut and gradually increasing it as needed under the guidance of a healthcare professional. Avoid combining phenibut with other sedatives or central nervous system depressants, as this may increase the risk of excessive drowsiness and other adverse effects.

Conclusion: How long does Phenibut normally last?

Phenibut's effects typically last between 15 to 24 hours, with several strategies available for prolonging its benefits, such as taking it with a meal, dividing the dosage, or using a sustained-release formulation. Combining phenibut with nootropic supplements like L-theanine, ashwagandha, or Bacopa Monnieri may also enhance its effects and extend its benefits. Phenibut can stay in the system for up to 26.5 hours, and its long-term effects are not well-established, warranting caution with prolonged use. Finally, phenibut can cause drowsiness, particularly at higher doses or when combined with other sedatives.

It is important to consult with a healthcare professional before using phenibut or combining it with other substances to ensure a safe and effective treatment plan. Phenibut is not approved for medical use in many countries, including the United States, and is often sold as a dietary supplement. As such, the quality and purity of phenibut products can vary significantly, further emphasizing the importance of caution and consultation with a healthcare professional before use.

Phenibut and Ashwagandha are two popular nootropic supplements known for their stress-reducing

In the realm of supplements designed to alleviate the symptoms of stress,

About the Author Chris Fraighten

Chris Fraighten is a leading biomedical researcher and currently the lead author of the Epimodels blog. He holds qualifications in chemistry, biology and is highly experienced in the fields of quantitative modelling and epidemiology. He brings this wealth of knowledge and experience to the Epimodels blog to bring you insightful, informative and interesting content on the latest advances in the space.