If you have ever looked at the ingredients in a men's sexual health supplement and seen Horny Goat Weed on the label, you were looking at a plant that contains one of the more clinically interesting compounds in natural men's health: icariin. Most people skip past it. This post explains what it actually is, how it works, and why it matters.
What Is Icariin?
Icariin is the primary bioactive flavonoid compound extracted from plants in the Epimedium genus, commonly known as Horny Goat Weed. It has been used in traditional Chinese medicine for over a thousand years, primarily for supporting male sexual function, bone health, and general vitality. Modern research has begun to explain the mechanisms behind those traditional uses, and the findings around erectile function are particularly relevant to men considering herbal supplements.
For a broader overview of how icariin works in the context of erectile dysfunction, Healthline covers Horny Goat Weed and icariin in detail including its mechanism of action and current research status.
How Does Icariin Work?
The mechanism that makes icariin relevant to men's sexual health is its ability to inhibit an enzyme called phosphodiesterase type 5, more commonly known as PDE5. If that sounds familiar, it is because PDE5 inhibition is also the mechanism behind the most widely prescribed erectile dysfunction medications on the market.
Here is the basic biology:
- When a man becomes sexually aroused, nitric oxide is released in the penile tissue
- This triggers the production of a molecule called cyclic guanosine monophosphate (cGMP), which relaxes smooth muscle tissue and allows blood to flow in and create an erection
- PDE5 is the enzyme that breaks cGMP down, effectively ending that process
- By inhibiting PDE5, icariin helps slow the breakdown of cGMP, which supports the conditions needed for an erection to occur and be maintained
This is not a claim that icariin works identically to prescription PDE5 inhibitors. The potency, speed, and reliability differ significantly. What it does mean is that icariin works via a recognised and well-understood biological pathway, which is more than can be said for many herbal compounds marketed for men's sexual health.
What Does the Research Say?
The majority of icariin research to date has been conducted in preclinical settings, meaning cell studies and animal models rather than large-scale human trials. That is an important distinction to make honestly. However the preclinical findings are strong enough that icariin has attracted serious scientific interest.
Key findings from published research include:
- A study published in the Asian Journal of Andrology (PMID: 12646997) isolated PDE5 from human platelet tissue and found that icariin showed dose-dependent inhibitory effects, concluding it is a cGMP-specific PDE5 inhibitor that may be developed into an oral agent for the treatment of erectile dysfunction
- A further study published in the Journal of Natural Products (PMID: 18778098) screened plant extracts traditionally used for male impotence and found that only Epimedium extract and its active principle icariin showed meaningful PDE5 inhibitory activity, with modified icariin derivatives approaching the potency of sildenafil
- Research published in the Journal of Sexual Medicine (PMC: 3551978) from the University of California demonstrated erectogenic and neurotrophic effects of icariin in vivo, with treated animals showing significantly higher intracavernous pressure and increased nitric oxide synthase expression in penile tissue compared to controls
Research has also explored icariin's role in supporting testosterone levels, bone density, and cardiovascular health, suggesting it has a broader physiological profile than a single-use compound. WebMD's breakdown of Horny Goat Weed covers the current evidence base in accessible terms.
How Does Icariin Compare to Prescription PDE5 Inhibitors?
| Feature | Icariin (Horny Goat Weed) | Prescription PDE5 Inhibitors |
|---|---|---|
| Mechanism | PDE5 inhibition via flavonoid compound | Direct PDE5 inhibition via synthetic compound |
| Potency | Lower, varies by extract concentration | High, clinically standardised dose |
| Onset time | 30 to 40 minutes, varies by individual | 15 to 60 minutes depending on medication |
| Prescription required | No | Yes |
| Human trial evidence | Limited, mostly preclinical | Extensive, FDA approved |
| Additional benefits | Bone health, testosterone support, antioxidant | Targeted to erectile function only |
| Side effect profile | Generally mild when used as directed | Headache, flushing, vision changes possible |
How Much Icariin Is in a Supplement and Does It Matter?
This is where a lot of men's health supplements fall short. Icariin content varies significantly depending on the extraction method and the part of the plant used. Things to be aware of when choosing a supplement:
- A product labelled as containing Horny Goat Weed may contain very little actual icariin if the extract is low quality or poorly standardised
- The effective icariin concentration in research studies is typically between 10 and 60 percent standardised extract
- Products that simply list Horny Goat Weed as a powder without specifying icariin content are often well below that threshold
- Always check whether the product specifies the icariin percentage of the extract rather than just listing the herb by weight
Which BuuBs Products Contain Icariin?
Herbal Mojo for Guys is the only product in the BuuBs range that contains Horny Goat Weed (Herba Epimedii) and therefore icariin. It is one of seven active herbal ingredients in the formula, alongside Tongkat Ali, Tribulus Terrestris, Maca Root, Ginkgo Biloba, Cnidium Monnieri, and Saw Palmetto. The combination targets multiple pathways simultaneously, with icariin providing the PDE5 inhibiting mechanism that makes the formula particularly distinctive among herbal on-demand supplements.
Stamina for Men and Erectimus do not contain icariin. Their formulas are built around Panax Ginseng, Maca Root, Damiana, and Ginkgo Biloba, which work via different but complementary mechanisms. For a full comparison of all three products see our supplement comparison guide.
Is Icariin Safe?
Icariin is generally considered well tolerated when taken in supplement form at recommended doses. There are no widely reported serious side effects associated with standard Horny Goat Weed supplementation. However the following men should exercise caution and speak with a healthcare professional before use:
- Men taking blood thinners or anticoagulant medication
- Men on blood pressure medication
- Men with existing cardiovascular conditions
- Men currently using prescription PDE5 inhibitors
Read our full medical disclaimer before using any supplement containing icariin. This post is informational and does not constitute medical advice.
The Bottom Line
Icariin is one of the few herbal compounds with a clearly understood mechanism of action relevant to erectile function. It is not a prescription drug and it does not carry the same potency or clinical evidence base as pharmaceutical PDE5 inhibitors. What it does offer is a biologically credible, naturally derived option for men who want on-demand support without a prescription conversation. The fact that it works via the same pathway as some of the most widely used medications in men's health is what makes it worth understanding.
If you have questions about whether a supplement containing icariin is right for you, contact us or speak with a healthcare professional before use.