Horny Goat Weed - Tolvaptan Interaction
Herbal: Horny Goat Weed
Also Known As: Epimedium grandiflorum, Barrenwort, Épimède, Épimède à Grandes Fleurs, Épimède du Japon, Epimedium, Epimedium Grandiflorum Radix, Herba Epimedii, Herbe Cornée de Chèvre, Hierba de Cabra en Celo, Japanese Epimedium, Xian Ling Pi, Yin Yang Huo
Drug: Tolvaptan
Brand names:
Samsca, Jynarque
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Jun 22, 2025
Interaction Details
Tolvaptan is classified as belonging to the following category: Cytochrome P450 3A4 (Cyp3A4) Substrates
Theoretically, horny goat weed might increase the effects and side effects of CYP3A4 substrates.
In vitro, horny goat weed extract inhibits CYP3A4 and suppresses CYP3A4 mRNA expression. This effect has not been reported in humans.
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
- Li K, Yu XH, Maskey AR, et al. Cytochrome P450 3A4 suppression by epimedium and active compound kaempferol leads to synergistic anti-inflammatory effect with corticosteroid. Front Pharmacol 2023;13:1042756.
Horny Goat Weed Overview
Horny goat weed, also known as epimedium, is a plant native to Asia and a member of the Berberidaceae family. It is known for its small, purple flowers and heart-shaped leaves.
In traditional medicine, horny goat weed is thought to have anti-inflammatory and pain-relieving effects, and it has been used to treat a variety of conditions, including digestive problems, respiratory infections, and skin disorders.
Horny goat weed is also commonly used as a natural treatment for male infertility and as a natural performance-enhancing supplement as it may have a mild androgenic effect.
Tolvaptan Overview
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Tolvaptan (Jynarque) is used to slow the worsening of kidney function in certain patients with autosomal dominant polycystic kidney disease (ADPKD; a certain type of inherited kidney disease). Tolvaptan (Jynarque) is in a class of medications called vasopressin V2 receptor antagonists. It works by increasing the amount of water released from the body as urine and decreases the growth of cysts in the kidneys. Removing fluid from the body and slowing the growth of cysts helps to slow the worsening of kidney function.
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Tolvaptan is also available as a tablet (Samsca) to treat low blood levels of sodium in people who have heart failure or certain other conditions. This monograph only gives information about tolvaptan tablets (Jynarque) to slow the worsening of kidney function in patients with ADPKD. If you are using this medication to treat low levels of sodium in the blood, read the monograph entitled tolvaptan (low blood sodium).
Horny Goat Weed - More Interactions
Horny Goat Weed interacts with 939 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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