Horsetail - Sustiva (Efavirenz) 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: Efavirenz
Brand names:
Sustiva
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Jul 22, 2023
Interaction Details
Efavirenz is classified as belonging to the following category: Efavirenz (Sustiva)
Theoretically, horsetail might decrease the levels and clinical effects of efavirenz.
In two case reports, patients were found to have detectable viral loads when taking horsetail-containing supplements along with an antiretroviral regimen that included efavirenz. 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 horsetail, the viral loads became undetectable in both cases. The exact mechanism of this interaction is unknown. It is also unclear if this interaction is specific to efavirenz or if it is 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.
Efavirenz Overview
-
Efavirenz is used along with other medications to treat human immunodeficiency virus (HIV) infection. Efavirenz is in a class of medications called non-nucleoside reverse transcriptase inhibitors (NNRTIs). It works by decreasing the amount of HIV in the blood. Although efavirenz does not cure HIV, it may decrease your chance of developing acquired immunodeficiency syndrome (AIDS) and HIV-related illnesses such as serious infections or cancer. Taking these medications along with practicing safer sex and making other life-style changes may decrease the risk of transmitting (spreading) the HIV virus to other people.
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. |
Return to the main herbal interaction checker page
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.
Ask A Pharmacist About Your Herbal Questions!
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!
Ask A Pharmacist