What is horny goat weed, and does it really work for ED?

Horny goat weed is perhaps the most literally named supplement of all time. Centuries ago, Chinese farmers noticed that goats seen eating the herb later seemed to be unusually “in the mood.” This herbal extract then became a mainstay treatment for erectile dysfunction (ED) in traditional Chinese medicine. It’s long since made its way into the ever-growing ED supplements industry, too. 

But does horny goat weed really work for ED? Is this herb the magical answer to all your libido and sexual performance woes? The short answer: Horny goat weed is definitely not a magical fix, and it doesn’t work nearly as well as scientifically-backed ED treatments like Viagra (sildenafil) or Cialis (tadalafil). Still, it might offer some benefits. 

Ahead, we take a closer look at what research has to say about the herb and its supposed superpowers for sexual dysfunction.

Horny goat weed is an extract from the Epimedium grandiflorum plant, a flowering shrub native to Asia, Africa, and parts of Europe. Also called by its Chinese name, yin yang huo, horny goat weed has been used for hundreds of years as a Chinese medicinal herb for treating ED and low libido. 

While this herb’s popularity in the East may have started with some snacking goats, it’s made a splash in the Western supplements industry over the past hundred years or so. Touted as an aphrodisiac and erection booster, horny goat weed is available in tablet, capsule, tea, or powder form—either on its own or as part of other supplement formulations. (It might be listed on a label as Epimedium, Epimedium sagittatum, Epimedium grandiflorum, or Epimedium koreanum). 

Before you run out and buy a bunch of horny goat weed supplements, though, be aware that there haven’t been any studies on how this particular herb works in humans—only in animals, and even those are limited. Let’s dig a little deeper to understand what we do know about this herb. 

The active ingredient in horny goat weed is icariin, a compound that’s been studied in animals for a wide range of possible perks. These include potential anti-inflammatory benefits, which could have a positive impact on diseases like cancer, asthma, lupus, and more—though it hasn’t been established in formalized clinical trials if humans actually experience these potential effects. 

Icariin also inhibits an enzyme called phosphodiesterase type 5 (PDE5), which is how drugs known as PDE5 inhibitors—e.g. Viagra, Cialis, Stendra (avanafil), and vardenafil—work. By blocking this enzyme, PDE5 inhibitors help relax blood vessels, which, in turn, improves blood flow to the penis. This makes it easier for people with ED to achieve and maintain an erection (with sexual arousal). 

So, does horny goat weed have the same effect as science-backed PDE5 inhibitors? Probably not. One large review study showed it’s likely far less effective than the more potent prescription options on the market. And we don’t really know how icariin or horny goat weed impact humans, since we only have animal studies available as of yet. 

Point being: The jury’s still out on how effective horny goat weed truly is at improving erections. 

In short: It probably won’t be the cure for ED you might be hoping for. 

When it comes to improving erectile function, numerous studies show that horny goat weed’s active ingredient, icariin, might work—at least in rats, though far less effectively than prescription medications like sildenafil (which, friendly reminder, is the active ingredient in Viagra). According to these rodent studies, icariin may repair damaged blood vessels, improve blood flow to the penis, and increase testosterone levels—all of which are factors associated with proper erectile function. 

Some other studies indicate Epimedium (the plant from which horny goat weed is extracted) may slow down cellular aging in rats. Since aging is a potential contributing factor of ED, it’s possible this anti-aging effect of the plant (and, in turn, horny goat weed) would positively impact erectile function in rodents. 

How might all this translate into humans? Unfortunately, we don’t know. There haven’t been any sizable studies on how horny goat weed or icariin may impact ED in humans. The aforementioned research suggests that this plant extract is probably at least 10-fold less potent than sildenafil. 

Also, given all the data we have is on rodents, not humans, we also don’t know how horny goat weed’s potency is impacted by food or how it potentially interacts with other supplements or medications. So, until and unless researchers study its effects on humans, we really don’t know whether horny goat weed would really work well enough to treat erectile problems in humans. 

If horny goat weed does work for ED—and that’s a big “if” in humans—here’s how. 

Its active ingredient, icariin, is a PDE5 inhibitor, similar to Viagra or Cialis—though significantly less potent than these prescription drugs. These medications inhibit (or block) the activity of an enzyme called PDE5—hence, the name of their drug class. 

PDE5 inhibitors affect various processes in the body, but one of their main mechanisms is facilitating the relaxation of smooth muscle in the penis and the dilation of blood vessels. This allows blood to flow more freely into the penis, creating an environment that’s conducive to getting and keeping healthy (read: hard) erections. They do this by blocking the PDE5 enzyme, which prevents the breakdown of cGMP—the chemical that helps relax smooth muscle and increase blood flow during arousal.  

There’s also some indication icariin may affect testosterone action, which can be important when it comes to libido. Think of it this way: The lower your libido, the harder it can be to get in the mood and, in turn, an erection. So, by potentially (keyword!) boosting testosterone action (i.e. how well it works in the body), icariin may help enhance sex drive, which could support erectile function. Icariin may also do this by helping repair damaged blood vessels and nerves that may be involved with ED. 

In rats treated with icariin, their testosterone levels did not increase; however, there was evidence of testosterone-like action by the icariin that could improve libido in humans. But again, this is largely theoretical since the research has been done almost exclusively on other animals, not humans. 

We don’t know exactly how fast horny goat weed might work for ED in humans since there haven’t been any direct human studies on this herb. But if it does help with erectile function, it probably takes a lot longer than Rx options. 

Viagra and Cialis, for example, both start working within 30–60 minutes, and they’re both highly effective at treating ED. Comparatively, horny goat weed has only been studied in rodents over the course of weeks or months and has been shown to be far less potent than the prescription PDE5 inhibitors on the market. 

One qualitative assessment explored online anecdotal reports about a variety of so-called sexual enhancement products, many of which contained horny goat weed. Lots of the products investigated had no effects, and some were reported to be quite harmful. But a couple of the products had anecdotal reports of being at least somewhat effective—after anywhere from 2–8 months. 

While we don’t know for sure how horny goat weed affects humans, it’s fair to assume from the evidence we do have that it would take a lot longer to work for ED than Viagra or Cialis. 

No, it doesn’t seem that way. In the Viagra vs. horny goat weed debate, limited rodent studies seem to suggest Viagra is probably far more potent—but, again, we can’t say for sure, given the lack of research on humans.

One more time for the folks in the back: Viagra is a PDE5 inhibitor that works, in part, by increasing blood flow to the penis. It does this by blocking the PDE5 enzyme, thereby relaxing the smooth muscles and dilating the blood vessels in that area. 

The active ingredient in horny goat weed, icariin, also inhibits the PDE5 enzyme, but far less potently than Viagra—or, at least, that’s what we know at this point. 

Without peer-reviewed human studies in which this herb is given to humans and compared to other drugs or placebo, we just can’t know if horny goat weed works in humans and, if so, if it works as well as Viagra. One thing we do know for sure is that Viagra is tested and regulated, while horny goat weed is not since it’s an herbal supplement. The plant extract comes in many varieties and is manufactured by different companies, so there is likely a lot of variation in the concentration and effectiveness of different preparations. There’s little to no regulation or safety data on over-the-counter (OTC) supplements like these, so we just don’t know how well it might work for ED. 

To recap, here are the main reasons it makes sense to ask your healthcare provider for prescription Viagra over trying horny goat weed: 

• Viagra is proven to be effective in humans. Where we have no scientific evidence about how horny goat weed affects humans, we have tons of research showing Viagra works well for ED in humans.

• Viagra is regulated by the US Food and Drug Administration (FDA), unlike horny goat weed. The FDA doesn’t regulate herbs and supplements like horny goat weed, so we don’t know how safe it is in its different forms. Viagra, on the other hand, is known to be safe for many people, and we have a good idea regarding how it interacts with other medications or supplements. 

• If you’re looking for results when you need them, Viagra is likely a much better bet. Viagra takes effect within 30–60 minutes, while anecdotal reports about horny goat weed indicate it probably takes at least a few months to kick in (if at all). Remember, it’s only safe to use Viagra that has been safely prescribed to you by a healthcare provider. Trying to buy Viagra over-the-counter or online is unsafe as it is unregulated and may contain unknown contaminants, not to mention unknown dosages of the active ingredient.

That’s not to say there’s no potential benefit to taking horny goat weed, though. It’s probably not the ED panacea many make it out to be, but it may offer some additional benefits. And on that note…

While horny goat weed’s benefits for erectile function and libido are murky, this popular herb might offer some additional perks. Again, we don’t have human studies, but there’s been some evidence that horny goat weed acts in ways that could theoretically offer benefits for the following medical conditions:

• Osteoporosis

• Fatigue and low energy

• Heart disease

• Neurodegenerative diseases

• Lipid disorders

• Chronic inflammation

Just like using horny goat weed for ED, none of these other potential benefits have been studied in humans. Rats seem to be getting a good number of health benefits from this herbal remedy, but we just don’t know that humans would fare the same. Still, if your healthcare provider deems horny goat weed safe for you to take alongside any other medications currently in your regimen and your current health status, then it might be worth trying. But again, that’s only if your healthcare provider gives the green light and guidance. 

According to some published studies, horny goat weed could be safe when taken by mouth in appropriate doses in the short term.  However, this herb can interfere with or change the action of a wide variety of medications, including drugs for high blood pressure and blood thinners.

Since horny goat weed hasn’t been studied in humans and, like any other OTC supplement, is not regulated by the FDA, there aren’t any official clinical trials that might help us understand its side effects. But, according to a qualitative assessment of online anecdotal reports, horny goat weed may cause any of the following side effects: 

• Upset stomach

• Hives

• Facial flushing

• Insomnia

• Increased heart rate

• Agitation or nervousness

• Nassau

• Dizziness

• Vomiting

It’s important to note that the supplements reviewed contained more than just horny goat weed, so the above side effects might have come from other substances. Horny goat weed may have additional adverse effects when taken with other medications, supplements, or health conditions. Be sure to talk to your healthcare provider before you add this to your regimen. 

All medications and supplements come with the potential for health risks and interactions with other medications or health conditions. Untested herbs like horny goat weed may have even more potential for harm since we just don’t know the full extent of its effects, nor can we confidently say what’s in one horny goat weed supplement vs. another. (Remember: Herbal supplements are not regulated by the FDA, so they don’t have to follow any strict guidelines for what they reveal on their label as for ingredients and other claims.) 

There’s some evidence that horny goat weed may increase the risk of bleeding because it has anticoagulation properties (meaning, it prevents the blood from clotting the way it normally would). So, if you have a bleeding disorder, you’re on blood thinners, or if you’re scheduled to have surgery, do not take horny goat weed.  

Horny goat weed may also impact hormones and hormone-related enzymes, like testosterone, aromatase, and 5-alpha reductase, though these effects aren’t super clear or well understood. Still, you shouldn’t take it if you have a hormone-sensitive cancer, like prostate cancer.

Because of these potential effects and interactions, it may be inadvisable to take horny goat weed if you’re on certain drugs or supplements, including: 

• Medications containing estrogen

• Medications that lower estrogens or block female hormones

• Medications or supplements that lower blood pressure

• Blood thinners or other medications or supplements that slow blood clotting

• Medications or supplements processed by the liver (many medications are processed by the liver)

Let your healthcare provider know about any dietary supplements and medications you’re taking, and ask them whether horny goat weed is safe for you to take.

If you struggle to get or maintain erections, there are options with a lot more research behind them than horny goat weed. 

ED medications

The first-line treatment for erectile dysfunction is a class of oral medications called PDE5 inhibitors, which include: 

• Viagra (sildenafil)

• Cialis (tadalafil)

• Vardenafil (the generic of brand-name Levitra, which has been discontinued)

• Stendra (avanafil)

These drugs take effect relatively quickly and are safe for most people. 

For those who are pill-phobic or just curious about other options, you can find certain PDE5 inhibitors in other formulations, such as: 

• Ro Sparks: This 2-in-1 treatment combines sildenafil and tadalafil (the active ingredients in Viagra and Cialis, respectively) in a sublingual form that dissolves under your tongue, allowing the medications to reach your bloodstream faster.  

• Ro’s Daily Rise Gummies: Each of these fruit-flavored gummies contains 7 mg of tadalafil. As their name indicates, they’re intended to be taken daily, so you can be ready 24/7 when the mood strikes. (Think: the spontaneity and perks awarded with daily Cialis, but in an easier-to-take form.)   

While these last two options are not specifically FDA-approved, their active ingredients are individually FDA-approved for the treatment of erectile dysfunction.

These PDE5 medications all come in different doses, take effect at different rates, and each person will respond better to some than others. As always, be sure to consult a healthcare provider—be it in-person or online through, say, Ro—to determine which, if any, of the above options might be the best ED treatment for you. 

Lifestyle changes

Addressing certain lifestyle factors can make a meaningful difference in improving ED and supporting long-term sexual health. These include:

• Regularly exercising. Staying physically active—especially with aerobic exercises like brisk walking, cycling, or swimming—can help improve circulation, support cardiovascular health, and lower the risk of ED-related conditions such as high blood pressure and obesity.

• Eating a balanced diet. A diet focused on whole, nutrient-rich foods like vegetables, fruits, whole grains, lean proteins, and healthy fats can support better blood flow and hormone balance. In contrast, diets high in processed foods, added sugars, and unhealthy fats may increase the likelihood of erectile issues.

• Prioritizing shut-eye. Inadequate or disrupted sleep can interfere with arousal and the body’s natural hormone cycles, including testosterone production, which is essential for sexual function. The general recommendation for adults is to aim for at least 7–9 hours per night. 

• Taking care of your mental health. Psychological factors like stress, anxiety, and depression can often play a role in ED. Therapy, mindfulness practices, or other stress-reducing strategies (e.g. deep breathing) can help improve mental wellbeing—and, in turn, sexual performance.

• Losing weight. Weight loss has been found to improve erectile function and testosterone levels in men, particularly those with obesity or overweight.

• Quitting smoking. Research suggests smoking can increase the risk of ED by around 50% for current smokers and around 20% for ex-smokers, as compared to never-smokers. So, it makes sense that kicking the habit can significantly improve down-there difficulties. 

• Cutting back on alcohol. Heavy or frequent alcohol use can interfere with sexual performance by affecting hormone levels, nerve function, and blood flow. Need help reducing your intake? Don’t be afraid to talk to your healthcare provider about safe strategies and resources. 

Other treatments

Other possible treatments for ED include penis pumps, prosthetics, injections, shockwave therapy, and even surgery in extreme cases. 

It’s important to know that ED can also be the first indication of more serious health issues, like heart disease, diabetes, or high blood pressure. So, if you’re having trouble getting or staying hard, you should speak with your healthcare provider to rule out any more serious complications—certainly before turning to unverified “treatments” like horny goat weed. 

While the name of this herb might give you the impression that it’s the answer to your erection woes, horny goat weed might not have the effects you’re hoping for. 

• Horny goat weed is an herb often used in traditional Chinese medicine for a wide range of ailments, including male sexual dysfunction. 

• It hasn’t been studied enough in humans, so we don’t know how well it works, if at all. Some animal studies indicate it might have positive effects, but it’s not clear those can be translated into humans. 

• Anecdotal reports imply some so-called sexual enhancement supplements containing horny goat weed may improve erectile function, but only after months of use, and it’s impossible to verify these reports. 

• Viagra, Cialis, and other research-backed prescription medications are far more effective and known to be safe for most people, though you should discuss the details with your healthcare provider. 

If you have ED, it’s important to speak with a qualified healthcare provider to get a full workup and determine the cause of your ED. In some cases, ED can be the first sign of a more serious health condition, so it’s important to rule out those possibilities before treating your erection problems. 

If you have more questions about horny goat weed, we’ve got you covered. Here are some common questions that might come up.