What does Horny Goat Weed do?

Traditional herb with weak human evidence for ED or bone health. Animal studies look promising but safety concerns exist.

Is Horny Goat Weed safe?

Documented case of severe muscle spasms, elevated creatine kinase, and elevated creatinine in a 33-year-old man after use — suggesting potential muscle and kidney toxicity

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Horny Goat Weed

Also known as: Epimedium, Herba Epimedii, Yin Yang Huo, Icariin, Epimedium sagittatum, Epimedium grandiflorum

Effective Dosage

No established dose from provided studies

What the Science Says

Horny Goat Weed is a plant from the Epimedium genus used for centuries in Traditional Chinese Medicine, primarily for sexual dysfunction and bone health. Its main active compound, icariin, has shown some ability to inhibit PDE5 (the same enzyme targeted by Viagra) and support nerve tissue in rat studies, but no well-designed human clinical trials confirm these effects. Animal research also suggests icariin may help preserve bone density and reduce atherosclerosis progression, though again, human evidence is lacking.

What It Doesn't Do

Not proven to treat erectile dysfunction in humans — the human studies simply don't exist yet. Won't reliably boost testosterone. Not a natural Viagra, despite what product labels imply. Online reviews for ED supplements containing this ingredient dropped by up to 90% after filtering out fake reviews. No proven bone health benefit in humans.

Evidence-Based Benefits

The active compound icariin has demonstrated phosphodiesterase type 5 (PDE5) inhibiting and neurotrophic effects in rat models of erectile dysfunction, with low-dose icariin (1 mg/kg) showing improved intracavernous pressure ratios (PMID: 20141584). In ovariectomized rat models, icariin showed significant improvements in bone mineral density and bone turnover markers, suggesting potential anti-osteoporosis effects (PMID: 29208188). In mouse atherosclerosis models, icariin reduced lesion area and macrophage infiltration via CX3CR1 downregulation (PMID: 26802470). All meaningful mechanistic findings are from animal studies only.

Weak Evidence

Effective at: No established dose from provided human clinical studies

Source: auto-research

Absorption & Bioavailability

Unknown — no human pharmacokinetic data in the provided studies. Animal studies use purified icariin extract, which may differ significantly from whole-herb supplements sold to consumers.

Red Flags to Watch For

Documented case of severe muscle spasms, elevated creatine kinase, and elevated creatinine in a 33-year-old man after use — suggesting potential muscle and kidney toxicity
Documented case of new-onset psychosis in a Parkinson's patient after use — serious neurological risk
Supplements on Amazon contain up to 33 mixed ingredients with no standardized dosing or purity regulation
Up to 90% of positive online reviews for ED supplements containing this ingredient were flagged as untrustworthy after analysis
No large human clinical trials exist to establish safe or effective dosing

Research Sources

PubMed
NIH DSLD

This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-04-06