Comfrey - Aspirin, Codeine Phosphate, Phenobarbital Interaction
Herbal: Comfrey
Also Known As: Symphytum officinale, Ass Ear, Beinwellwurzel, Black Root, Blackwort, Bruisewort, Common Comfrey, Consolidae Radix, Consoude, Consoude Officinale, Consound, Consuelda, Grande Consoude, Gum Plant, Healing Herb, Herbe aux Charpentiers, Herbe à la Coupure, Knitback
Drug: Aspirin, Codeine Phosphate, Phenobarbital
Brand names:
Phenaphen
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
May 25, 2025
Interaction Details
Aspirin, Codeine Phosphate, Phenobarbital is classified as belonging to the following category: Cytochrome P450 3A4 (Cyp3A4) Inducers
Theoretically, CYP3A4 inducers might increase the risk of adverse effects from the pyrrolizidine alkaloid constituents in comfrey.
CYP3A4 enzymes convert pyrrolizidine alkaloids, constituents of comfrey, to toxic metabolites. Some case reports show that enzyme inducers, such as phenobarbital, seem to enhance the toxicity of comfrey.
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
- Stickel F, Seitz HK. The efficacy and safety of comfrey. Public Health Nutr 2000;3:501-8.
- Chojkier M. Hepatic sinusoidal-obstruction syndrome: toxicity of pyrrolizidine alkaloids. J Hepatol 2003;39:437-46.
- Wang YP, Yan J, Fu PP, Chou MW. Human liver microsomal reduction of pyrrolizidine alkaloid N-oxides to form the corresponding carcinogenic parent alkaloid. Toxicol Lett 2005;155:411-20.
Comfrey Overview
Comfrey (Symphytum officinale) is an herbaceous plant that belongs to the borage family (Boraginaceae). It is native to Europe and Asia and is known for its hairy, green leaves and small, purple, bell-shaped flowers.
Comfrey has a long history of use in traditional medicine and contains a number of active compounds, including allantoin, which is believed to have anti-inflammatory and healing properties. It has been traditionally used to treat a variety of ailments, including wounds, fractures, and skin conditions. In addition, comfrey is believed to have astringent and expectorant effects, and has been used to treat respiratory disorders and coughs. It is important to note that comfrey may cause liver damage if taken in large amounts (orally) or over a long period of time and should be used with caution. The FDA has recommended removal of oral comfrey products from the market due to potential for liver toxicity although it is currently still available. It is most often seen in topical forms (e.g., as an ointment).
Comfrey - More Interactions
Comfrey interacts with 410 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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Dr. Brian Staiger, PharmD
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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