Horny Goat Weed (Epimedium)
Commonly used for
Men's Health
Where to Buy
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The cheapest product is usually low quality, but more expensive doesn’t always mean better.
What is it? / Overview
Icariin, the main active flavonoid, inhibits phosphodiesterase-5 -- the same enzyme target as sildenafil -- and enhances nitric oxide signaling in animal and in-vitro models, which is the mechanistic basis for the traditional erectile-enhancement use. This hasn't been confirmed in well-designed human trials.
How is it used? / Administration
Form: Epimedium spp. extract standardized to icariin
Typical dose studied: No validated human dose -- products vary widely in icariin content
Timing: Not established
Ships trigger-empty given the lack of human efficacy data -- the two practical flags worth surfacing are the nitrate/PDE5-inhibitor interaction and the documented risk of undeclared pharmaceutical adulteration in this product category.
How well does it work? / Evidence
? Emerging / limited evidence
Who should avoid it?
Avoid with: Chronic coronary disease / Coronary artery disease; Primary hypertension / High blood pressure
Interacts with: Nitrates and PDE5 inhibitors (e.g. sildenafil) -- theoretical additive vasodilation and hypotension, clinically important given icariin's PDE5-inhibitor-like mechanism; Antihypertensives -- theoretical additive blood-pressure lowering
Already taking it? Robust human clinical trial evidence is essentially absent, and products in this category are a documented target for adulteration with actual PDE5-inhibitor drugs -- worth knowing what's actually in a given product before continuing.
Research & references
Bella AJ, Shamloul R (2014). Traditional Plant Aphrodisiacs and Male Sexual Dysfunction. Phytotherapy Research. Friș AS et al. (2026). An Overview of the Phytochemistry, Biological Activities and Therapeutic Potential of Epimedium SPP. Plants.
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