Have you considered clinical trials for Erectile dysfunction?

We make it easy for you to participate in a clinical trial for Erectile dysfunction, and get access to the latest treatments not yet widely available - and be a part of finding a cure.

What is erectile dysfunction?

Erectile dysfunction (ED) is very common, especially in older men. The percentage of men who have been affected increases dramatically with age.

The Massachusetts Aging study¹ reported that 52% of middle-aged men experience erectile dysfunction. By 70 years of age, this proportion increases to 70%.

Erectile dysfunction is defined as the failure to produce a satisfactory erection. Primarily, people with ED are unable to get an erection, but it also includes the inability to maintain an erection during sexual activity.

What is the mechanism behind an erection?

Let's briefly look at the underlying mechanism so it is easier to understand possible treatments.

Erections can be caused by one of two things:

  • Touch (reflexogenic reflex)

  • Thought (psychogenic reflex)

Both will lead to an increase in nitric oxide (NO). This molecule signals the penis to relax.

This sounds counterproductive, but it allows the penis to be filled with blood and become erect. As a result, the veins in the penis will also collapse, preventing blood from leaving.

What causes erectile dysfunction?

Many factors can cause ED. The research divides these into two major groups:

  • Psychological

  • Physical

Psychological factors impair signals from your brain to your penis. This is very common in younger males because their bodies are generally healthy at this age.

One example is performance anxiety. You might be feeling anxious about performing in bed, and this affects the brain sending signals to your penis.

ED can also be caused by physical factors, for example, damage to your nerves or blood vessels. It is reported that 80%² of ED cases have a physical cause, particularly blood flow problems. Risk factors include:

  • Age

  • Diabetes

  • High cholesterol

The psychological causes tend to be situation-dependent, whereas the physical factors tend to progress over time.

What are the symptoms?

The primary symptom of ED is the physical inability to produce an erection when you want to have sex. There are also significant physiological implications that come with ED.

Studies² have reported that men with ED often feel less of a man, depressed, insecure, and anxious.

What are the treatment options?

There are many ways to treat ED, including:

  • Changing certain lifestyle factors, e.g., giving up smoking

  • Over-the-counter (OTC) medication

  • Prescription medication

  • Talk therapy

  • Surgery

How do over-the-counter medications differ from prescription medications?

OTC medication does not require a doctor to prescribe the medication. In general, these drugs are safer for consumption in terms of side effects and the potential for abuse.

It is reported that 90%³ of Americans use OTC medication. OTC pills are available through a registered pharmacy where you can request a certain medication. This process reduces the need for a doctor's visit, so it is generally more convenient for the consumer.

What are the over-the-counter medications available for ED?

If you do not feel comfortable talking to your doctor about erectile dysfunction, the following OTC medications may be worth considering.

Dehydroepiandrosterone (DHEA) supplements

DHEA is a steroid that is naturally produced in your body. It is the precursor to sex hormones and is used to make testosterone and estrogen. It is involved in smooth-muscle relaxation.

The drop in DHEA is thought to contribute to the mechanism behind ED. Risk factors for low DHEA include old age, stress, and ED. It has been reported that 80-year-olds have levels as low as 10%–20% compared to younger adults.

Low levels of DHEA have been clinically linked to ED, and DHEA supplementation aims to increase levels of the steroid.

Bear in mind that while studies have shown DHEA supplements to be promising, a 2018 review of ten studies⁴ concluded that the studies were small with inconclusive results.

A typical starting dose is approximately 25–50mg per day.


Yohimbine is a compound made from the Yohimbe tree that is native to Africa. It has been used in African regions for centuries to treat a wide variety of conditions, including ED. Despite its longstanding reputation, no human clinical trials have been conducted.

Yohimbine works by blocking adrenergic receptors in the brain. This allows the brain to be more primed toward having an erection. Because it acts on the brain, its effect tends to work better if you have psychological causes of erectile dysfunction.

A meta-analysis of seven randomized trials⁵ with more than 400 participants with ED determined this extract to be better than a placebo. Other studies, however, have demonstrated weak evidence of its efficacy.


L-arginine is an amino acid. Amino acids are organic compounds essential to the body because they act as the building blocks of protein. We usually receive enough L-arginine through our diet, and it is found in high concentrations in foods such as vegetables and whole grains.

L-arginine can be taken as a supplement which increases its levels in our bodies. People with ED can have problems with the production of nitric oxide — the protein essential for smooth-muscle relaxation — and increasing the levels of L-arginine is thought to increase nitric oxide levels.

The starting recommended dose is 2g daily. Lower doses have been found to have no effect.

A meta-analysis⁶ investigating dosages of 1,500–5,000mg over three months found a significant improvement. However, because it is not specifically for treating ED, any benefits from taking the supplement may take longer to appear.

L-arginine is more successful if you have problems with blood flow. It is thought that in these cases, people have lower levels of nitric oxide so its effect is more pronounced. It is important to note that, in the analysis, L-arginine did not affect people with severe vascular problems.


Carnitine is another amino acid found in meat and dairy products. It is important for creating energy that the body can use.

As carnitine has been found to decrease as we age, it is thought that increasing carnitine levels will improve energy production in the penis, increase nitric oxide, and improve blood flow.

One study⁷ compared the use of carnitine and testosterone over six months and found that carnitine had greater success in relieving ED symptoms.

Those involved reported that they were able to successfully get an erection which occurred more quickly and lasted for a longer time. This is an important finding, as increasing testosterone has more significant side effects, such as an increased risk of benign prostatism.

It is recommended that you start with 500–1,000mg daily and take it with food.


Ginseng is a popular herb used to treat several medical conditions. It has several pharmacologically active compounds and is thought to work on ED in three ways:

  • Increases nitric oxide levels 

  • Improves cardiovascular functioning

  • Provides an anti-fatigue effect 

A meta-analysis of nine randomized controlled trials concluded weak evidence of ginseng improving erectile function. There was a weak association⁸ with self-reported sexual performance, but this was not considered to be of significance.

The downsides of over-the-counter medications

The FDA does not tightly regulate this class of medication. Drug manufacturers need to disclose what is in the pills, but not the exact amounts. It is for this reason that the medications might not work.

Dosage and effect are important concepts when considering taking a drug, as the effect of a drug is significantly linked to the dosage you take. It is also important to consider how much you take because taking more of a drug will lead to an increased risk of side effects.

When to see a doctor

You should seek medical advice if ED is significantly affecting you. Physicians can diagnose and treat this condition in multiple ways depending on the cause and your particular medical condition.

The lowdown

Over-the-counter medications would appear to be of questionable value for the treatment of erectile dysfunction. While generally considered safe if taken at the recommended dosage levels, there is little research to support their claims, and no randomized controlled trials have been conducted on such supplements. Components of these products have been found to show little to moderate improvement in erectile function.

Erectile dysfunction is an extremely common problem amongst men of all ages. Effective treatment is available, and anyone struggling with the issue should consult with their doctor regarding the available options.

Have you considered clinical trials for Erectile dysfunction?

We make it easy for you to participate in a clinical trial for Erectile dysfunction, and get access to the latest treatments not yet widely available - and be a part of finding a cure.

Discover which clinical trials you are eligible for

Do you want to know if there are any Erectile dysfunction clinical trials you might be eligible for?
Have you taken medication for Erectile dysfunction?
Have you been diagnosed with Erectile dysfunction?