What Drugs Interact With Phenibut?

In our latest question and answer, the pharmacist discusses potential drug interactions with phenibut, a supplement used for anxiety.

Feb 03, 2018

Socialphobe asked

My Dr. has me on 300mg of buropion xl and just started me on 10 mg in the morning and at night of buspirone. I suffer from extreme social anxiety and haven't had any relief. I learned of the supplement Phenibut and was wondering if it's safe to take with my other meds. I will only use it when I have a event I need to be present for. So maybe once every other week. Any interactions I should be aware of? 


There unfortunately have been no studies in regard to potential drug interactions between phenibut and prescription medication such as buproprion and buspirone. It is therefore difficult to give a recommendation on safe use of the supplement with your medications. If you do intend to try phenibut, it would be prudent to make your doctor aware so you can be appropriately monitored for side effects and adverse reactions.

Phenibut Information & Drug Interactions

Phenibut is a chemical derivative of gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter. GABA is a common target of many prescription medications, including antidepressants and anxiolytics. Studies have shown that phenibut is a GABA receptor agonist (i.e. stimulates response), and therefore has inhibitory effects in the central nervous system. Studies in animals have shown that phenibut can decrease anxiety but can also cause sedation and decrease respiration.

While phenibut may be beneficial for the treatment of anxiety symptoms, there is insufficient safety information regarding its use. At the very least, it should be used with caution with medications known to affect GABA or ones that can reduce respiration rate such as:

  • Benzodiazepines
  • Antidepressants
  • Opioids (e.g. oxycodone, hydrocodone)

Buspirone, a commonly used anxiolytic, does appear to have some effect on GABA and therefore should be used cautiously with phenibut to avoid additive side effects.

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