Horny goat weed is a traditional Chinese medicinal herb. It is also known by its many botanical names, including Epimedium, and its Chinese name, yin yang huo.

As a form of alternative medicine, the herb has been used to treat conditions from hay fever to atherosclerosis, nerve pain fatigue, osteoporosis, and erectile dysfunction.

Human research data to support the use of horny goat weed is limited at best. However, there is some anecdotal evidence for using the herb to treat certain medical conditions.

Uses and research

There have been studies conducted on cells in laboratories that report evidence of several beneficial properties of horny goat weed. Early research suggests that it may have properties that can keep bones strong, protect the nerves, and support the immune system.

Other cell research has revealed the following possible effects:

• anticancer effects
• anti-HIV activity
• radiosensitizing effects
• reversal of multidrug resistance in some tumor cells
• postmenopausal bone loss prevention

Atherosclerosis is a condition where the arteries in the neck harden. For people with atherosclerosis, a mixture containing horny goat weed may be beneficial and result in improved symptoms and clinical tests.

People with hay fever may experience symptom relief and a reduction in white blood cells that tend to increase with allergies.

Horny goat weed and erectile dysfunction

One study looked at rats with injured nerves and nerve cells grown in a lab. The researchers reported that icariin, the active component of horny goat weed, might show positive and promising effects in treating erectile dysfunction (ED) caused by nerve injury.

ED is a common problem affecting men, especially those aged 40-70 years old. Nearly 20 million men in the United States are affected by the condition, which can have many causes. At times, men may experience psychological conditions, such as depression or anxiety, that may cause or contribute to ED.

ED has 2 categories:

• Primary ED: Men affected by this rare condition have never been able to have or sustain a penile erection. Primary ED is often due to a physical abnormality or a psychological cause.
• Secondary ED: This form is typically caused by a physical condition. Causes range from conditions such as diabetes, stroke, multiple sclerosis, and physical injuries. This group of men will likely have had erections in the past.

Certain medications, such as those to treat high blood pressure, diabetes, high cholesterol, depression, cancer, and long-term pain, may contribute to the condition. Some of these medications include:

• beta-blockers
• clonidine
• spironolactone
• thiazide diuretics
• alcohol and drugs such as cocaine
• opioids
• SSRI and tricyclic antidepressants
• anxiolytics
• monoamine oxidase inhibitors (MAOIs)
• amphetamines
• 5 alpha-reductase inhibitors
• anticholinergics
• cimetidine
• hormonal therapies

Although there is some evidence that horny goat weed may offer symptom relief in certain medical conditions, additional research is necessary.

Dosing

As with any medications, herbs, and supplements, it is important for people to speak to their doctor before using horny goat weed. A doctor can work out its safety and dosage based on an individual’s needs and medical history.

For the treatment of atherosclerosis and ED, the University of Michigan recommends taking 5 grams 3 times per day. For the treatment of hay fever, it is recommended to simmer 500 milligrams in 250 milliliters of water for 10-15 minutes and consume 3 times daily.

People should check with their doctor to see if seeping in water is required when treating themselves with horny goat weed. Typically, the herb is mixed in a tonic to decrease the risk of side effects.

Alternative medicine should not take the place of traditional medicine or be used in the place of recommendations from a doctor.

High doses of horny goat weed have been associated with breathing difficulty, vomiting, and nausea.

Side effects and interactions

As with any medication or herbal supplement, some people may experience side effects or adverse reactions when using horny goat weed. Possible side effects may include:

• mood changes such as irritability and aggression
• racing heart
• increased energy
• sweating
• feelings of being hot
• decreased thyroid function
• nausea

It is important for people to speak to a doctor about these or any other side effects that occur with the use of horny goat weed.

Interactions

Horny goat weed may interact with certain medications that include:

• cortisone
• prednisone
• prednisolone
• methylprednisolone
• dexamethasone
• cytochrome P450 substrates
• aromatase Inhibitors, such as anastrozole, exemestane, and letrozole

People should not take horny goat weed if they:

• have hormone-sensitive cancer, as the herb has been shown to promote estrogen production
• have heart disease as it can potentially lead to a rapid irregular heartbeat, shortness of breath, and excitability
• have a known sensitivity to Epimedium
• are taking aromatase inhibitors such as anastrozole, exemestane, and letrozole
• have been recommended not to do so by a doctor

Anyone who is considering using horny goat weed should discuss it with their doctor first. Health experts can determine if horny goat weed is right for someone and what the appropriate dosing would be.

There have not been enough studies to recommend the use of this herb and to ensure its safety.

The U.S. Food and Drug Administration (FDA) and other government agencies do not monitor the quality, purity, or safety of herbs and extra caution is recommended.

More studies are needed to guarantee safety and identify potential side effects. If anyone does purchase herbs, they should be sure to buy from a known and reputable source.