St. John's Wort - Aspirin, Codeine Phosphate, Phenobarbital Interaction
Herbal: St. John's Wort
Also Known As: Hypericum perforatum, Amber Touch-and-Heal, Barbe de Saint-Jean, Chasse-diable, Demon Chaser, Fuga Daemonum, Hardhay, Herbe Aux Mille Vertus, Hypereikon, Hyperici Herba, Hypericum, Millepertuis, Perforate St. John's Wort, Racecourse Weed, Rosin Rose, Saynt Johannes Wort
Drug: Aspirin, Codeine Phosphate, Phenobarbital
Brand names:
Phenaphen
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
May 04, 2025
Interaction Details
Aspirin, Codeine Phosphate, Phenobarbital is classified as belonging to the following category: Phenobarbital (Luminal)
St. John's wort decreases the levels and clinical effects of phenobarbital.
St. John's wort may increase the metabolism of phenobarbital. Plasma concentrations of phenobarbital should be monitored carefully. The dose of phenobarbital may need to be increased when St. John's wort is started and decreased when it is stopped.
Interaction Rating
Likelihood of Occurrence
LikelyWell-controlled human studies have demonstrated the likely existence of this interaction
References
- Henderson L, Yue QY, Bergquist C, et al. St John's wort (Hypericum perforatum): drug interactions and clinical outcomes. Br J Clin Pharmacol 2002;54:349-56..
Interaction Details
Aspirin, Codeine Phosphate, Phenobarbital is classified as belonging to the following category: Cytochrome P450 2B6 (Cyp2B6) Substrates
St. John's wort may increase the metabolism and reduce the levels of CYP2B6 substrates.
Clinical research shows that taking St. John's wort 325 mg three times daily for 14 days along with bupropion, a CYP2B6 substrate, reduces the area under the concentration-time curve by approximately 14% and increases the clearance of bupropion by approximately 20%.
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
- Lei HP, Yu XY, Xie HT, et al. Effect of St. John's wort supplementation on the pharmacokinetics of bupropion in healthy male Chinese volunteers. Xenobiotica 2010;40(4):275-81.
St. John's Wort Overview
St. John's wort (Hypericum perforatum) is a plant native to Europe and is known for its medicinal properties. St. John's wort has been used to treat a variety of conditions, including depression, anxiety, and sleep disorders. It is one of the most extensively used and researched natural medicines in the world, and is thought to work similarly to certain conventional antidepressants by increasing the levels of serotonin in the brain.
St. John's Wort - More Interactions
St. John's Wort interacts with 1115 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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