Horny Goat Weed
Research reviewed: up until 03/23
Horny Goat Weed (Epimedium) is a dietary supplement with 6 published peer-reviewed studies involving 175 participants, researched for Erectile functions, Postmenopausal symptoms.
Evidence at a Glance
Strength is scored by study design, sample size, study type, and outcomes
Erectile functions
WeakPostmenopausal symptoms
ModerateResearch Visualised
Visual breakdown of the clinical data.
Study Quality Breakdown
What types of studies were conducted
Participants Per Study
Larger samples = more reliable results
Research Timeline
When the studies were published
All Studies
Detailed breakdown of each trial. Click to expand.
Erectile functions
To evaluate the effects of icariin (icariin is the main active component of horny goat weed) on penile blood flow and tissues in cavernous nerve-injured rats (the cavernous nerve is the main autonomic nerve that regulates penile erection).
Study Type
Rats with erectile dysfunction due to nerve injury
Purpose
To evaluate the effects of icariin (icariin is the main active component of horny goat weed) on penile blood flow and tissues in cavernous nerve-injured rats (the cavernous nerve is the main autonomic nerve that regulates penile erection).
Dose
1, 5, and 10 mg/kg of icariin
Duration
4 weeks
Results
Daily treatment with low-dose icariin for 4 weeks improved penile blood flow dynamics in rats. Compared to the control, the researchers detected significantly higher neuronal nitric oxide synthase in the penile tissue. This is an enzyme that helps to generate nitric oxide which initiates penile erections. More specifically, nitric oxide is needed for the muscles in the penis to relax. This relaxation allows chambers inside the penis to fill with blood so the penis becomes erect. Conclusion: This study indicates that icariin (found in horny goat weed) may improve penile blood flow. Penile blood flow is essential for erections. Clinical studies are needed to investigate its efficacy in humans.
To investigate the effect of icariin on erectile function and the expression of nitric oxide synthase* in castrated rats.*Nitric oxide synthase generates nitric oxide that initiates penile erections.
Study Type
Rats with erectile dysfunction due to nerve injury
Purpose
To investigate the effect of icariin on erectile function and the expression of nitric oxide synthase* in castrated rats.*Nitric oxide synthase generates nitric oxide that initiates penile erections.
Dose
1 mg/kg/day and 5 mg/kg/day
Duration
4 weeks
Results
Several markers of erectile function improved in most treatment groups: In 2 out of 3 treatment groups, the expression (activation) of two forms of nitric oxide synthase significantly improved in the erectile tissue of rats. Note that nitric oxide synthase generates nitric oxide which initiates penile erections. In 1 of the treatment groups, phosphodiasterase-5 was significantly decreased. Note that phosphodiesterase-5 interferes with blood flow to the penis that is needed for an erection. Conclusion: Oral treatment with icariin for 4 weeks potentially improves erectile function in rodents.
To investigate the effects of orally administered icariin on the expression (levels) of nitrogen oxide synthase* in the erectile tissue of rats with erectile dysfunction.
Study Type
Rats with erectile dysfunction
Purpose
To investigate the effects of orally administered icariin on the expression (levels) of nitrogen oxide synthase* in the erectile tissue of rats with erectile dysfunction.
Dose
5 mg/kg/day or 10 mg/kg/day
Duration
30 days
Results
Chronic oral treatment with icariin increases erectile function and restores nitric oxide synthase* in the erectile tissue of rats.
To investigate the effect of icariin on phosphodiesterase-5
Study Type
Laboratory study
Purpose
To investigate the effect of icariin on phosphodiesterase-5
Results
Icariin exhibited inhibitory effects on all forms of phosphodiesterase-5.
Postmenopausal symptoms
To evaluate the effects of dried Epimedium extract on blood lipid levels and sex hormone levels (estradiol, progesterone and testosterone). Background information: Horny goat weed contains phytoestrogens, compounds that act like the hormone estrogen.
Study Type
Randomised, double-blind, placebo-controlled clinical trial
Purpose
To evaluate the effects of dried Epimedium extract on blood lipid levels and sex hormone levels (estradiol, progesterone and testosterone). Background information: Horny goat weed contains phytoestrogens, compounds that act like the hormone estrogen.
Dose
300mL of hot water Epimedium extract (with 25% icariin)
Participants
90 postmenopausal women
Duration
6 months
Results
Epimedium water extract was associated with a significant increase in blood levels of estradiol (an estrogen hormone) compared with the pre-treatment level. It was also associated with a significant decrease in total cholesterol and total triglyceride levels.
To investigate the effect of the phytoestrogen flavonoids derived from Epimedium brevicornum maxim (horny goat weed) on bone loss in postmenopausal women.
Study Type
Randomised, double-blind, placebo-controlled clinical trial
Purpose
To investigate the effect of the phytoestrogen flavonoids derived from Epimedium brevicornum maxim (horny goat weed) on bone loss in postmenopausal women.
Dose
60mg icariin (with 15mg Daidzein and 3mg Genistein) paired with 300mg elemental calcium daily
Participants
85 healthy late postmenopausal women
Duration
24 months
Results
Phytoestrogen flavonoids from horny goat weed were associated with preventative effects on bone loss in late postmenopausal women.
Frequently Asked Questions
Common questions about Horny Goat Weed research
There are currently 6 peer-reviewed studies on Horny Goat Weed (Epimedium), involving 175 total participants. Research covers Erectile functions, Postmenopausal symptoms. The overall evidence strength is rated as Moderate.
The evidence is currently rated as "Moderate Evidence". This rating is based on study design quality (randomisation, blinding, placebo controls), sample sizes, study types (2 human studies, 4 animal studies), and reported outcomes.
Horny Goat Weed has been researched for: Erectile functions, Postmenopausal symptoms. Each area has its own body of evidence which you can explore in the study breakdowns above.
Yes, 2 out of 6 studies are human trials. The remaining 4 are animal studies. Human trials carry more weight in our evidence scoring system.
