Phenibut - Dyphylline, Ephedrine, Guaifenesin, Phenobarbital Interaction
Herbal: Phenibut
Also Known As: Beta-phenyl-gamma-aminobutyric acid, 4-Amino-3-Phenylbutyric Acid, B-(Aminomethyl)-Benzenepropanoic Acid, Beta-(Aminomethyl)-Hydrocinnamic Acid, B-Phenyl-Gamma-Aminobutyric Acid, Beta-Phenyl-GABA, Beta-Phenyl-Gamma-Aminobutyric Acid, Fenibut, Phénibut, Phenigam
Drug: Dyphylline, Ephedrine, Guaifenesin, Phenobarbital
Brand names:
Lufyllin-EPG
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
May 04, 2025
Interaction Details
Dyphylline, Ephedrine, Guaifenesin, Phenobarbital is classified as belonging to the following category: Cns Depressants
Theoretically, phenibut might increase the risk of sedation and respiratory depression when taken with CNS depressants.
Phenibut has been associated with sedation and respiratory depression in several case reports, especially when taken at high doses.
Interaction Rating
Likelihood of Occurrence
PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
References
- Downes MA, Berling IL, Mostafa A, Grice J, Roberts MS, Isbister GK. Acute behavioural disturbance associated with phenibut purchased via an internet supplier. Clin Toxicol (Phila). 2015;53(7):636-8.
- O'Connell CW, Schneir AB, Hwang JQ, Cantrell FL. Phenibut, the appearance of another potentially dangerous product in the United States. Am J Med. 2014 Aug;127(8):e3-4.
- Sankary S, Canino P, Jackson J. Phenibut overdose. AM J Emerg Med. 2017 Mar;35(3):516.e1-516.e2.
- Graves JM, Dilley J, Kubsad S, Liebelt E. Notes from the field: phenibut exposures reported to poison centers - United States, 2009-2019. MMWR Morb Mortal Wkly Rep 2020;69(35):1227-8.
Phenibut Overview
Phenibut is a central nervous system depressant that is commonly used for its anxiolytic and sedative effects. It is a derivative of the neurotransmitter GABA, an inhibitory neurotransmitter, and is thought to work by enhancing the activity of GABA in the brain. It is structurally similar to several prescription drugs, including gabapentin, pregabalin, and baclofen.
Phenibut - More Interactions
Phenibut interacts with 247 drugs
Interaction Rating Key
These severity listings are for informational use only. Never start, stop or otherwise change your therapy before speaking with your provider.
| Major | The combined use of these agents is strongly discouraged as serious side effects or other negative outcomes could occur. |
| Moderate | Use cautiously under the care of a healthcare professional or avoid this combination. A significant interaction or negative outcome could occur. |
| Minor | Be aware that there is a chance of an interaction. Watch for warning signs of a potential interaction. |
| Unknown | No interactions have been reported or no interaction data is currently available. |
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Parts of this content are provided by the Therapeutic Research Center, LLC.
DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.
© 2021 Therapeutic Research Center, LLC
Drug descriptions are provided by MedlinePlus.
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In addition to being a clinical pharmacist specializing in pharmacotherapy, Dr. Brian Staiger is a registered herbalist through the American Herbalist Guild. He has combined his passion for pharmacy practice with the study of medical ethnobotany to improve patient care. Feel free to reach out about any of your herbal or medication questions!
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