Herbs being grinded in the bowl

Horny Goat Weed: Benefits, Uses, Side Effects

With a name that suggests virility—it’s unsurprising that people have used horny goat weed for centuries as an aphrodisiac.

However, anecdotal evidence indicates that its benefits might extend beyond its libido-enhancing powers. But, are these reported effects grounded in science or purely hearsay?

This article reveals the surprising truth about horny goat weed—what it is, how it works, and whether medical proof exists for its purported advantages.

What Exactly Is Horny Goat Weed?

light bulbScientifically named Epimedium, this flowering plant is also referred to under many other labels such as bishop’s hat, barrenwort, and fairy wings. However, in the West, it’s most often known as horny goat weed.1

According to legend, this nomenclature was given to the plant by a Chinese goat-herder. He observed that his herds became overtly sexual after consuming horny goat weed and named it yin yang huo—literally translated as rampant goat.2 3

This plant, in the Berberidaceae family, is found mainly growing in the wild over southern China. Horny goat weed is also found to a limited extent in the Asian countries on its immediate borders—such as Vietnam and Myanmar.4 5

LeafIt’s prevalence within China meant that its use became widespread in TCM (traditional Chinese medicine). However, while there are around 60 species of horny goat weed, usually it’s the Epimedium grandiflorum and Epimedium sagittatum species which proponents use for therapeutic benefits.6

Visually, the flower of the horny goat weed plant appears like a hat (hence one of its names). It possesses four petals, angled downwards which are topped by four further sepals—usually brightly colored.

How Does Horny Goat Weed Work?

Researchers have suggested that the active components within horny goat weed are the flavonoids. These are the parts of a plant that are responsible for pigmentation, filtering ultraviolet light, and cell messaging. 7 8

ScientistOf these, the one which scientists assume has the most beneficial effects is icariin. This compound has two crucial characteristics, which make it useful for medical use. It promotes the production of nitric oxide and acts as a PDE5 (phosphodiesterase type 5) inhibitor.9 10

Nitric oxide is a gas that acts as a vasodilator. It relaxes the vascular system allowing the vessels to dilate—improving the blood supply throughout the body.11

PDE5 is an enzyme that stops smooth muscles (such as in the penis and retina) from relaxing. In the case of the genitalia, this can prevent erections. By inhibiting this action—icariin can theoretically help those suffering from erectile dysfunction.12 

These physiological effects have led to people using horny goat weed for various uses.

Here are the most popular:

Aphrodisiac

man and woman signFor centuries, both men and women have taken horny goat weed as an aphrodisiac. However, there’s no scientific evidence that this plant possesses any libido raising abilities.13

That being said, many people swear by this plant as a powerfully effective booster of their sex-drive. This could be down to the placebo effect, or perhaps it possesses properties hitherto undiscovered by the scientific community.

However, that’s not to discount horny goat weed as a sexual enhancer—as discussed in the next section.

Erectile Dysfunction

Unfortunately, this is a remarkably common issue amongst men—the inability to either obtain or maintain, an erection.

Magnifying glass and a bar chart Research shows that the prevalence of this condition increases by 10 percent with every decade of life. Hence, 40 percent of men in their 40s suffer from this problem, 50 percent in their 50s etc.14

Horny goat weed’s two main features—inhibiting PDE5 and boosting nitric oxide production—both benefit men suffering from erectile dysfunction. Interestingly, it works through the same process as the prescription drug sildenafil (Viagra).15

By preventing PDE5 from functioning, horny goat weed allows both the smooth muscles of the penis and the corpora cavernosa—the erectile tissue—to relax. This makes them more responsive and reactive to blood flow. 16

The nitric oxide elevating feature of horny goat weed dilates the blood vessels leading into the penis. This enables more blood to flow into the genital area, therefore causing firmer erections.

Magnifying glass and computer screenScientists have illustrated that not only is horny goat weed a useful treatment for erectile dysfunction—but also its efficacy under some circumstances is equal to sildenafil.17

While there have been few human studies—numerous experiments on rats have indicated enhanced erectile power and longevity.18

High Blood Pressure

Initially, scientists developed the now world-famous Viagra as a treatment for hypertension (high blood pressure).

Measuring blood pressureWhile effective in this regard, the clinical trials also demonstrated that it promoted erections. As this was an altogether more profitable route—Pfizer, the company behind it—made it available as an erectile dysfunction drug. Although, it’s still prescribed to treat blood pressure issues in some circumstances.19

As Viagra and horny goat weed work in similar ways—it’s therefore, no surprise that the latter is also a useful treatment for hypertension.

Its vasodilating and PDE5 inhibiting actions allow blood to flow more freely—like widening a freeway to prevent traffic jams—lowering blood pressure.20

Osteoporosis

X-ray of left armAs we age—the higher the chance of developing this disease—which leads to the weakening of the bones. While women are more likely to suffer most—the male skeleton loses strength too. Scientific papers state that one in every three men over 75 suffer from this condition.21

Medical researchers conducted a study on 100 women over a two year period. During this time, 50 percent of them were treated with horny goat weed daily (containing 60 mg of icariin)—the other half with a placebo.22

The results were very positive. They indicated that women using horny goat weed demonstrated a 1.5 percent increase in bone mineral density—while those on the placebo lost mass.

Studies conducted on rats produced similar results. Experts deduced that this was due to the ability of horny goat weed to promote muscle growth by stimulating the relevant bone-building proteins.23

Hay Fever

Sick Also known as allergic rhinitis, this condition occurs where the immune system drastically overreacts to allergens in the air. This results in inflammation of the nose and eyes which can be quite unpleasant.

Anecdotally, many people declare that horny goat weed can alleviate these annoying reactions. Although, there have been no studies examining its effects on hay fever sufferers.

However, what is known is that horny goat weed, or specifically icariin, acts as both an anti-inflammatory and keeps the immune system in check.24

Hence, by lowering swelling and preventing the body from reacting badly to allergens—horny goat weed could be an effective treatment for hay fever.

Memory Loss

BrainAs we age, not only do we begin to suffer from inhibited brain function, but our chance of developing Alzheimer’s disease also increases.25

Scientists studying rats treated with horny goat weed witnessed elevated learning capacity and heightened memory function.26

Furthermore, studies from 2017 show that icariin acts as a neuroprotector. It inhibits the effects of amyloid beta-mediated neurotoxicity—the process which causes Alzheimer’s disease.27

Cancer

Cancer ribbonA 2010 study explained that horny goat weed could act to inhibit the enzymes which promote cancerous tumor growth.28

While research continues to show that it has a preventative effect—it’s currently unknown whether this compound has any abilities to alleviate the condition once it’s begun.

Estrogen

Many of the symptoms encountered by menopausal women occur due to the decreased production of the female hormone estrogen.29

Analysis iconExperts have found that horny goat weed has positive estrogen effects—increasing its production. While this may have benefits for women in relieving menopausal issues—including osteoporosis—in men, it’s a mixed bag.

Men do require estrogen to remain healthy. It’s essential for strong bone mass, cardiovascular function, libido, and fertility.30

However, too much of this hormone, and it throws the male physiology out of balance.

Horny goat weed promotes estrogen through aromatization. That is, it metabolizes current testosterone stores into this female hormone. If testosterone levels are already low—taking too much horny goat weed could make estrogen the most potent hormone in the male body.

Body fatThis change in balance could lead to gynecomastia (male breasts), water retention, and fat gain.31

Cardiovascular

Research conducted on rats has demonstrated that horny goat weed has the benefits of:

  • Preventing the death of heart cells.
  • Lowering oxidative stress.
  • Improving overall cardiac function.

As such, experts suggest that supplementing with this compound can have a protective effect on the heart. 32

Energy

Whether a fitness enthusiast or just someone who needs a little boost in their daily lives—horny goat weed has beneficial properties.

energyThe elevated nitric oxide levels that this plant induces increases blood supply to the muscles. Furthermore, with improved blood volumes—oxygenation of the tissues and organs also elevates.33

Hence, during exercise (including sex) or the regular day-to-day routine—stamina improves as the body can work more efficiently.

Additionally, if you’re a bodybuilder, this can enhance muscle growth. Blood supplies beneficial nutrients to the tissues, allowing them to build faster and more substantially.

Where to Buy Horny Goat Weed?

While you can find this plant in nature—and its leaves are edible—retailers rarely make this raw horny goat weed product available for sale. What’s more, the plant itself is said to be extremely bitter in taste.

Instead, it’s usually purchased in a refined and processed form—either as a tea or capsules.

Tea cupThe least common variety is horny goat weed tea. In this state, the plant leaves have been pre-boiled, cooked, and then soaked during production to reduce the overwhelming bitterness. They’re then dried and packaged. The user simply adds boiling water to make herbal tea.

Most frequently, horny goat weed is supplied in capsule form—taken daily.

These pills are widely available from online nutrition and health stores, in addition to being sold over the counter in high-street stores.

How Much Horny Goat Weed Should I Take?

Two people are having a conversationFirstly, as with any supplement taken to treat a specific medical condition, it’s recommended that you first speak with your health care professional before use.

That being said, most scientists consider horny goat weed to be safe—as long as you follow the manufacturer’s instructions regarding consumption.

PillsTypically, users ingest a daily dose of 750 mg to 1200 mg, usually achieved in one or two pills. However, when looking at the label, it’s important to check the levels of icariin the supplement contains.

As this flavonoid is considered the active compound within horny goat weed, theoretically, the higher the percentage of icariin in the supplement, the more productive it will be. Across supplements, these can range between 3-40 percent.

Nevertheless—there is a proviso.

As scientists have completed little clinical research of horny goat weed’s effects on humans—this dose may not always be effective. What nutritionists have done, is examined the efficacious doses on rodents—and then scaled them up for human use.

When to Take Horny Goat Weed?

For overall health benefits such as increased bone density, lowered blood pressure, and improved heart function—you should take one to two tablets between meals every day.

ClockSome users believe that when taken for sexual dysfunction problems—consuming 1200 mg 30-45 minutes before sexual intercourse is beneficial. Although, this recommendation is based on anecdotal evidence—not scientific.

How Long Does It Take for Horny Goat Weed to Work?

The rate at which you begin to notice results from taking horny goat weed depends on the dosage, icariin content, gender, and individual physiology.

However, as medical practitioners have conducted few human studies, it’s difficult to ascertain a specific time frame in which you’ll witness the benefits you desire.

Where scientists have completed research on men and women, such as the osteoporosis study mentioned earlier, it appears that the positive results take some time. In that particular case, two years.

However, that study isn’t possibly the most representative, as bones aren’t particularly fast-growing.

Anecdotally, users indicate that for lowering blood pressure and alleviating the symptoms of erectile dysfunction—the benefits occur around weeks four to five of use.

GrowthHorny goat weed works on a cumulative basis. Meaning, every day that you take it, nitric oxide levels and its physiological benefits increase a little more.

This means it’s essential not to miss a dose when using horny goat weed.

What Are the Horny Goat Weed Side Effects?

If you buy a horny goat weed supplement from a trusted and respected supplier—the chances of developing any side effects are minimal. It’s important to stress that this is a natural product, and the FDA (US Food and Drug Administration) permits its over-the-counter sale.

However, as with any product, some people do suffer from adverse effects.

It appears that the majority of these are related to the cardiovascular system—especially the fact that horny goat weed lowers blood pressure.

Rash on a man's faceSome users have experienced nosebleeds, dizziness, and a rash.34

These reports are in the minority. Yet, if you find that you do suffer from any unwanted side effects after consuming horny goat weed—cease use immediately.

Who Should Not Take Horny Goat Weed?

Although generally considered safe—some people should avoid horny goat weed.

The Memorial Sloan-Kettering Cancer Center advises that it shouldn’t be taken by those who suffer from hormone-related cancer and/or heart disease.35

Stop iconTheir evidence stems from a case where a man, who already had congestive heart failure, took horny goat weed. He was taken to hospital with shortness of breath, an irregular heartbeat, and chest pains.36

Additionally, the medical community recommends that people using certain medications should also avoid this compound, including:

  • Treatment for blood pressure—high and low.
  • Medications which may cause an irregular heartbeat.
  • Pills that act as blood thinners.
  • Beta-blockers.
  • Treatments for hormone-related cancer—for example, breast or ovarian cancer.
  • Thyroid disease medications.
  • Ibuprofen.

Hence, if you’re using any of the above—consult with your physician first before consuming horny goat weed.

MaternityFinally, as its researchers have not tested this compound on pregnant women or those who are breastfeeding, it’s sensible not to use horny goat weed.

Horny Goat Weed Research

The good news is that scientists have conducted extensive research on horny goat weed—specifically on its active flavonoid icariin.

However, there’s some bad news too.

These clinical studies are usually in vitro (that is, conducted in a test tube) or on rodents. There are very few live human experiments.

While the positive results witnessed by scientists may apply to humans—without further research, this has to remain theoretical.

Scientist working behind the computerFurthermore, a few studies have begun to question its potency. While some reports have concluded that horny goat weed may be as effective as Viagra—more recent research indicates this is inaccurate. With results showing that Viagra is eight times more powerful than its natural counterpart.37

Finally, the long-term effects of horny goat weed are unknown. The medical community has not investigated its use over an extended period.

Summary

Although being one of the oldest “traditional” medicines—it seems that horny goat weed remains highly relevant today.

Its theoretical ability to address erectile dysfunction, heart disease, memory loss, and high blood pressure means it addresses modern-day health issues.

While it’s important to bear in mind that there’s a current lack of human research—existing studies indicate that its reported effects do have a basis in science.

This article has been medically reviewed by Dr. Biswadeep Das on August 2019

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  36. https://www.sciencedirect.com/science/article/abs/pii/S0033318204701450?via%3Dihub

  37. https://pubs.acs.org/doi/pdf/10.1021/np800049y 

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