Horny Goat Weed: Benefits, Dosage & Safety

Written on April 13, 2022

What it is | How erections occur | How it works | Benefits | Side Effects | Dosage | The Best Horny Goat Weed Supplements | The Bottom Line

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What it is

Horny Goat Weed (Epimedium) is a plant that has purported sexual health benefits. It is also known as yin yang huo, barrenwort, bishop’s hat or fairy wings.

It is available over-the-counter and is commonly used for sexual performance and erectile dysfunction. There is limited scientific evidence that Horny Goat Weed is effective f0r libido although there is preliminary evidence suggesting that it may activate anti-aging pathways. Anecdotally, horny goat weed may lead to improved libido, increase blood circulation, increase estrogen in post-menopausal women and enhance testosterone.

New formulations of horny goat weed have been developed to contain increased levels of the active ingredient (icariin) with the goal of increasing effectiveness.

How erections occur

When sexually stimulated, nitric oxide (NO) signals cyclic guanosine monophosphate (cGMP) to inhibit smooth muscle contraction. This causes an inflow of blood into the penis which leads to an erection. The active ingredient known as icariin can increase NO synthesis in the penis leading to arousal.

In those with ED, phosphodiesterase type 5 (PDE5) inhibits nitric oxide and cGMP which can hinder sexual performance [1].

How it works

The active compound in horny goat weed is known as icariin. Icariin inhibits phosphodiesterase-5 (PDE5), an enzyme that restricts blood flow.

Horny goat weed increases blood flow to your penis and genitalia, leading to an erection. It does so by increasing nitric oxide synthesis.

Compared to viagra, icariin is far weaker (around 80 times less potent).

Other effects

In addition to its effects on libido, horny goat weed can enhance brain blood flow and enhance brain function. The active ingredient icariin can cross the blood-brain barrier, reduce pro-inflammatory molecules and reduce oxidative stress [2].

In addition to the cognitive benefit, icariin can increase testosterone and enhance bone health [3].

Benefits

1. May improve libido and erectile dysfunction

Erectile dysfunction can affect people of all ages but the prevalence of ED increases as you age. As a risk factor for CVD, dementia and all-cause mortality, ED can have serious health consequences [4].

Men with ED are 1.33-6.24 more likely to have benign prostatic hyperplasia (BPH) than those without ED [5][6]. It appears that lifestyle, culture and diet affect ED as in some rural populations, the rate of ED is only around 1-2% [7].

Horny goat weed led to improved sexual health and immunity in those undergoing hemodialysis [8].

In older men

The benefits of icariin have been mostly studied in older patients and are limited.

A Japanese herbal blend containing horny goat weed improved erectile function in older males (average age 62.7) [9].

In animal studies

In rats, icariin improved the erectile function and NO levels after 1mg/kg/day for 4 weeks [10].

Another rat study gave doses of 0 – 200 mg/kg body weight for 35 days and found an increase in antioxidative activity at 50-100 mg/kg [11]. A dose of 50 and 100 mg/kg led to increased testosterone levels. The higher dose heightened oxidative stress, so there is definitely a balance that needs to be found when supplementing icariin. Doses of 50 and 100 mg/kg led to increased epididymal sperm counts.

In animal studies, icariin can improve circulating levels of testosterone and may help bone formation whilst limiting bone breakdown [12]. Icariin also prevented cell death in penile artery.

2. Improves bone growth and prevents bone loss

Horny goat weed may reduce bone loss in postmenopausal women and in men.

A 2 year clinical trial found epimedium-derived flanonoids (horny goat weed) was beneficial for bone health. There was an increase in lumbar spine bone health, with no difference at the femoral neck but increased bone density in those taking epimedium [13].

A five year randomized control trial found that the group receiving supplementation of epimedium in combination with herbal medicine (Fufang) had increased bone mineral density and resulted in less than half the fracture risk than the control [14].

In animal studies, horny goat weed and its constituent ingredients can reduce the risk of bone fracture and reduce bone loss induced by estrogen deficiency  [15][16][3][17].

3. May protect the heart

Horny goat weed can reduce oxidative stress and therefore may have heart benefits.

The benefits of horny goat weed for heart health in elderly people who had kidney deficiency and heart disease was significant.  A 75% improvement in brain activity (via electroencephalogram) was observed in those with cerebral arterosclerosis [18].

In animal studies, epimedium can reduce oxidative damage in the heart, lower cholesterol levels and reduce the risk of blood clotting.

Epimedium provided to rats can have a cardioprotective effect against ischaemia and reperfusion (I/R) injury. I/R injury occurs when the heart is starved of oxygen due to reduced blood supply often due to a build-up of plaque in the wall of the arteries leading to the heart. The epimedium compound led to reduced oxidative stress and cell death in the heart compared to the control [19]. It also significantly improved cardiac function by activating the PI3K-Akt signaling pathway.

A 2011 study examined the effect of horny goat weed compounds on cardiac function and mitochondrial health in diabetic rats for 8 weeks. Rats treated with icariin had a higher levels of superoxide dismutase (SOD) which reduces mitochondrial oxidative stress [20].

Another study found that horny goat weed can reduce the risk of blood clotting in rabbits & lower blood cholesterol independently of its-lipid lowering effects [21].

4. May delay aging

This has not been proven in humans however in animal studies, icariin can activate anti-aging pathways.

Sirtuins are a silent information regulation protease family [22]. Sirtuins, especially SIRT1 and SIRT6 have been researched for their role in longevity [23][22].

In mice, icariin has shown anti-aging benefits by increasing SIRT6 and inhibiting a pathway known as the NF-kB pathway [24].

Symptoms of aging were reduced in a clinical trial of 49 Japanese men taking a combination therapy containing icariin and other herbal medicines [9].

Unreplicated Benefits:

Brain

Icariin has also been shown to reduce beta-amyloid deposits in the brain in mice [25]. It may be a promising treatment in patients with Alzheimer’s disease.

Along with this study, icariin has been shown to improve spatial working memory, reduce APP and enhance the neurogenesis in the hippocampus of mice [26].

Body Fat

Icariin can prevent the associated body weight and fat gain from high fructose and high salt diets [27].

Other benefits

Perimenopause syndrome treated with epimedium complexes can lead to a regulating effect on the nervous system [28].

Platelet related cardiovascular disorders can result in serious health consequences including heart attack. The epimedium koreanum Nakai has been shown in vitra and in vivo to have antiplatelt and antithrombotic effects [29].

General benefits of icariin can extend to SIRT6 activation, which regulates metabolism, aging and disease [30].

Side Effects

Side effects are generally rare but the most common are fever, increased heart rate, aggressiveness, irritability and nausea.

Drug Interactions

Always consult your doctor prior to supplementing as horny goat weed can affect the efficacy of certain medications.

These include aromatase inhibitors, cytochrome P450 substrates and blood pressure medications.

Horny goat weed is not recommended for those with cancer or heart disease.

Horny goat weed can increase estrogen levels and therefore may increase the risk of breast and uterine cancers as they are hormone sensitive cancers.

Horny goat weed can slow blood clotting and may increase the risk of bleeding disorders.

Dosage

The typical dose ranges from 60mg-1200 mg per day. Most supplements contain 250-1000 mg per pill, with increments at 250, 500, 750 and 1000 mg.

Extrapolating dosages from animal studies indicate therapeutic dosages at 80 mg/kg icariin.

The Best Horny Goat Weed

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Despite its relative lack of strength, certain people have found benefit from supplementing Horny Goat Weed. For this reason we recommend a few superior supplements. We’ve ranked the best horny goat weed supplements by price and reviews.

Best Horny Goat Weed Overall: Source Naturals Horny Goat Weed

Best Horny Goat Weed Complex for Libido: Gaia Herbs Libido Complex

Best Value Horny Goat Weed: NOW Horny Goat Weed

Verdict: Safe but not particularly effective

Another risk of Horny Goat Weed are enhanced estrogen levels in the body arising from long term use. This effect appears to be isolated to the phytoestrogen icariin. However this side effect occurs rarely and only after months to years.

The Bottom Line

Horny Goat Weed has been used in traditional chinese medicine for its effects on libido and general health.

However the evidence suggests that it is far weaker than prescription medications that work by the same mechanism.

Horny goat weed can raise levels of estrogen in the body and should not be taken by those suffering from or at risk of bladder or uterine cancers. This is because horny goat weed can affect hormonal function.

There is exciting research being done into horny goat weeds benefits for longevity, particularly its effects on SIRT1 & SIRT6.

Overall, we have adequate evidence that it is largely an ineffective supplement.