Horsetail - Descovy (Emtricitabine, Tenofovir Alafenamide Fumarate) Interaction
Herbal: Horsetail
Also Known As: Equisetum arvense, Alligator Cane, Asprêle, Bottle Brush, Cavalinha, Coda Cavallina, Cola de Caballo, Common Horsetail, Corn Horsetail, Dutch Rushes, Equiseti Herba, Field Horsetail, Fleshy Grass-Tail, Giant Horsetail, Great Horsetail, Herba Equiseti, Herbe à Récurer, Hor
Drug: Emtricitabine, Tenofovir Alafenamide Fumarate
Brand names:
Descovy
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
May 18, 2025
Interaction Details
Emtricitabine, Tenofovir Alafenamide Fumarate is classified as belonging to the following category: Nucleoside Reverse Transcriptase Inhibitors (Nrtis)
Theoretically, horsetail might decrease the levels and clinical effects of NRTIs.
In two case reports, patients were found to have detectable viral loads when taking horsetail-containing supplements along with an antiretroviral therapy. In one case, the antiretroviral regimen included zidovudine, lamivudine, and efavirenz; in the other case, the regimen consisted of emtricitabine, tenofovir disoproxil fumarate, and efavirenz. One month after discontinuing the supplement, the viral loads became undetectable in both cases. The exact mechanism of these interactions is unknown. It is also unclear if these interactions are specific to NRTIs or if they are related to various components of antiretroviral therapy.
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
- Cordova E, Morganti L, Rodriguez C. Possible Drug-Herb Interaction between Herbal Supplement Containing Horsetail (Equisetum arvense) and Antiretroviral Drugs. J Int Assoc Provid AIDS Care. 2017;16(1):11-13.
Horsetail Overview
Horsetail, also known as equisetum, is a type of perennial herb that belongs to the Equisetaceae family. It is native to much of the Northern Hemisphere and has distinctive, jointed stems that resemble the tail of a horse, hence common name. Some species of horsetail are used medicinally and have been traditionally used to treat a range of ailments, including kidney and bladder problems, wounds, and hair loss. It is most commonly used in traditional medicine as an oral diuretic (i.e., water pill) for the treatment of edema. It is important to note that some species of horsetail (e.g., Equisetum palustre) may be toxic and should not be consumed. Additionally, some types of horsetail contain thiaminase, which can cause thiamine deficiency with prolonged use.
Horsetail - More Interactions
Horsetail interacts with 185 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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