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Everything You Need To Know About Erectile Dysfunction Drugs

Better erections, coming up.

Fast Facts

  • PDE5 inhibitors are medications that are used to treat erectile dysfunction.
  • The drugs attach to an enzyme in the bloodstream and block it from breaking down a chemical compound that enables the blood vessels in the penis to dilate.
  • PDE5 inhibitors are also used to treat conditions including pulmonary hypertension and premature ejaculation.

Google searches for erectile dysfunction meds turn up plenty of sketchy over the counter ed pills and sham sexual enhancement boosters. Scroll past those dodgy ads and you’ll get to the legit stuff: a class of medications called phosphodiesterase 5 (PDE5) inhibitors. These are FDA approved male enhancement pills that help men suffering from ED.

PDE5 inhibitors improve blood flow, including to the penis. Since erectile dysfunction (1) is largely a blood flow problem PDE5 inhibitors can help most men who experience ED.

There are four different PDE5 inhibitors: tadalafil (sold under the brand name Cialis), sildenafil (Viagra), vardenafil (Levitra), and avanafil (Stendra).

Let’s look at these meds more closely, explain the differences, and figure out if they can help with any erection woes you’re experiencing.

What are PDE5 Inhibitors?

PDE5 inhibitors were initially developed to treat chest pain, high blood pressure and heart problems by—you guessed it—improving blood flow. In clinical trails researchers noticed another benefit: Patients who were taking the medication reported better erections. 

ED affects at least 12 million men in the U.S. and the older you are, the more likely you are to experience it. About 40 percent of men in their 40s and nearly 70 percent of men in their 70s suffer from ED. Younger men aren’t immune, though: about a quarter of men under 40 have erectile dysfunction. 

PDE5 inhibitors are the front line treatment for erectile dysfunction. Unlike over the counter (OTC) meds that claim to boost erections, you can only get them through a pharmacy using a prescription from your doctor.

How Do PDE5 Inhibitors Work?

To better understand how these FDA approved male enhancement pills work and how they can help treat ED, let’s quickly review how your body gets and keeps an erection.

When you’re sexually stimulated, nerve impulses in your body release neurotransmitters, or chemical messengers, into two spongy cylinders of tissue in your penis called the corpora cavernosa.

These chemical messengers tell the blood vessels in your penis to dilate, so that more blood can enter. As blood flows into the corpora cavernosa, they expand—and so does your penis. 

Fibrous tissue called the tunica albuginea traps the blood in the corpora cavernosa, keeping your erection long enough for sex.

The important link to all of this is cyclic guanosine monophosphate (cGMP). Cyclic GMP relaxes the muscles inside the blood vessels of your penis to increase blood flow.

PDE5 is an enzyme that binds to and breaks down cGMP, decreasing its effect. 

PDE5 inhibitors attach to PDE5 in the bloodstream and prevent it from blunting the effects of cGMP. As cGMP levels increase, more blood can reach your penis, and you have firmer erections that last longer. Science. 

PDE5 inhibitors only treat ED. They can’t boost your
 libido or cause you to get random erections. You need to be sexually stimulated for the drugs to work.


How PDE5s Help ED

A host of medical conditions can cause erectile dysfunction. Big culprits include diabetes, high blood pressure, high cholesterol, heart disease, and vascular disease—all of which can decrease blood flow to the extremities, including your penis

But other factors are also to blame. Certain medications (prescription and non-Rx), smoking, drinking to excess, and not getting enough sleep or exercise are all linked to ED.

Depression, stress, performance anxiety, and relationship issues can also play a role.

When you talk to your doctor about ED, they should do a full workup to find out what’s preventing you from getting and keeping an erection. One of the things they should test for is low testosterone since ED is a common symptom in men with low T. 

Testosterone replacement therapy (TRT) can help boost your sex drive, and studies show it can improve erectile function in males with mild ED.

If you’re concerned that you could have low testosterone, Hone’s at-home test can tell you if your levels are in the normal range. 

If the test shows that your T level is low and ED is one of your symptoms, a Hone physician can help you determine the best treatment, which may include testosterone replacement therapy (TRT) and PDE5 inhibitors.

Could Low T Be Causing Your ED?

Low testosterone can cause ED. Hone’s at-home test analyzes your T. If it’s low, a physician can prescribe treatment to boost your T—and your erections.

Common PDE5 Inhibitors

There are four FDA-approved male enhancement pills: sildenafil, vardenafil, tadalafil, and avanafil.

These FDA male enhancement pills are taken between 15 minutes to an hour before sex depending and in most cases you should take them on an empty stomach. So if your planned romantic interlude involves a steak dinner first, you may have to do some careful planning.



Generic Name(s)


When to take it

How long it lasts




An hour before sex

Around 4 hours



Staxyn and Levitra


An hour before sex

4-8 hours




15-30 minutes before sex

Up to 6 hours





30-60 minutes before sex

Around 4 hours


As the oldest PDE5 inhibitor on the market (it was approved by the FDA to treat ED in 1998), sildenafil is also the most studied—there’s plenty of data from clinical studies regarding its safety. It’s also a popular choice because of its low cost.

Sold in generic and under the brand name Viagra, sildenafil is also FDA-approved approved for treating pulmonary arterial hypertension—a high blood pressure in the lungs that’s caused by a blockage in their small arteries—when marketed under the brand name Revatio.

Sildenafil is usually prescribed in doses from 25-100mg and should be taken about an hour before sex. One dose lasts about four hours.

Hone offers sildenafil for men with low testosterone who are experiencing ED. You’ll need to take an at-home hormone test and have a consultation with a licensed provider who can determine if a prescription is appropriate.

hone health sildenafil


A PDE5 inhibitor sold under the brand names Staxyn and Levitra, vardenafil was approved by the FDA in August of 2003, and is also available as a generic.

Vardenafil’s chemical makeup may require smaller dosing to make you erect—as little as 10mg can do the trick. 

Erections with vardenafil last from four to eight hours (2).


Sold under the brand name Cialis, tadalafil is known for having a longer duration of action than other PDE5 inhibitors.

A single dose of tadalafil can provide relief up to 36 hours. One study found it was effective 72 hours after taking (3).

A standard dose of tadalafil is 10-20mg, taken at least an hour before sex. Listen to your doctor about how much to take and when.

Unlike some other ED meds, tadalafil doesn’t need to be taken on an empty stomach.

In addition to boosting your erections, tadalafil may also significantly boost your self-esteem and confidence (4). 

Tadalafil is also used to treat pulmonary arterial hypertension (5) and some studies indicate larger doses can also improve exercise capacity and duration. A lower daily dose has been shown to help with benign prostatic hypertrophy (BPH)—aka an enlarged prostate.

Hone offers tadalafil for men with low testosterone who are experiencing ED. You’ll need to take an at-home hormone test and have a consultation with a licensed provider who can determine if a prescription is appropriate.


Hone Health Tadalafil


Sold under the brand name Stendra, avanafil is the newest option on the market. It was approved by the FDA for treating ED in 2012 and there isn’t a generic option available just yet.

Because there isn’t a generic option available yet, avanafil can be more expensive than other PDE5 inhibitors, and some studies suggest that it may not be as effective at lowering blood pressure.

Avanafil can start to provide relief from erectile dysfunction in as little as 15 minutes, making it a good option for people whose sexual activity tends to be more spontaneous.

It’s less likely than other PDE5 inhibitors to cause certain side effects such as vision issues.


Better Sex Ahead

If low T is zapping your erections, Hone can help. Start with an at-home hormone test today.

Risks and Side Effects

Like any medication, there are risks and side effects associated with PDE5 inhibitors. It’s important to discuss your individual medical history with your doctor before starting treatment. 

If you have a heart condition, you should also check with your cardiologist before taking PDE5 inhibitors.

Tell your doctor right away if you experience any side effects. The most common side effects of PDE5 inhibitors are headache, flushing, and dyspepsia (stomach upset). But clue him or her in if you experience any of these less common side effects:

Dangerously low blood pressure, especially in those with a history of a heart condition

  • Hearing loss or ringing in your ears
  • Dizziness
  • Altered color vision
  • Back pain
  • Nasal congestion

One of the best-known side effects of PDE5 inhibitors is priapism—an erection that lasts longer than four hours—though this is rare.

Who Shouldn’t Take PDE5 Inhibitors?

If you’ve experienced any of these conditions, make sure your doctor knows about them before you discuss using a PDE5 inhibitor, as the medication may not be right for you:

  • Low blood pressure
  • Uncontrolled high blood pressure
  • Heart failure
  • Angina
  • Heart attack within the past 90 days
  • Stroke within the last 6 months
  • Aortic stenosis
  • Penile deformities
  • Nitrate use or alpha blockers
  • Sickle Cell Disease
  • Multiple Myeloma
  • Leukemia

Other Conditions Treated with PDE5 Inhibitors

Although these FDA approved male enhancement pils are approved for treating ED, PDE5 inhibitors are prescribed for these other conditions:

Pulmonary Hypertension (PH)

PH occurs when the blood pressure in the vessels of the lungs is elevated. PDE5 inhibitors alleviate this condition by dilating the arteries in the lungs, just as they do in the penis (6).

Premature Ejaculation (PE)

PDE5 inhibitors have been shown to relieve symptoms of PE when it is associated with ED. The meds keep the contractile tissue of the penis and its accessory glands from contracting too soon, which would otherwise cause premature ejaculation (7).

Altitude Sickness

Sildenafil has been shown to reduce altitude sickness, particularly in people with pulmonary hypertension (8).

Penile Rehabilitation after Radical Prostatectomy

After a radical prostatectomy—surgical removal of the prostate gland and attached seminal vesicles—sildenafil has been found to improve regeneration of the nerve that causes erections, which can be damaged during surgery (9).

Natural Sources of PDE5 Inhibitors

There is some research investigating natural sources of PDE5 inhibitors, such as ginger, Paullinia cupana, muira puama and l- citrulline (10). However, the effects of these substances are being evaluated in animal studies and are not considered safe for human use. 

The FDA warns against supplements for treating ED because supplements are regulated and could contain harmful ingredients. The safety and effectiveness of these supplements also hasn’t been adequately studied. For now, stick to the FDA approved pharmaceuticals.

How Much Do PDE5 Inhibitors Cost?

Most PDE5 inhibitors can be found in generic forms and, if prescribed by your doctor, may be covered by your insurance.

Could Low T Be Causing Your ED?

Low testosterone can cause ED. Hone’s at-home test analyzes your T. If it’s low, a physician can prescribe treatment to boost your T—and your erections.

The Bottom Line

PDE5 inhibitors are a safe, effective class of medications used to treat erectile dysfunction. If you are struggling to get or keep an erection, speak to a doctor. If you are prescribed a PDE5 inhibitor, take it according to the instructions on the label. 

1. McVary KT (2007). Clinical practice. Erectile dysfunction.
2. Porst H, et al (2006). Extended duration of efficacy of vardenafil when taken 8 hours before intercourse: a randomized, double-blind, placebo-controlled study.
3. Evans, Jeffery D, and Stephen R Hill (2015). A comparison of the available phosphodiesterase-5 inhibitors in the treatment of erectile dysfunction: a focus on avanafil.
4.  Li JP, et al (2010). Efficacy of low-dose tadalafil on ED assessed by Self-Esteem and Relationship Questionnaire.
5. Henrie, Adam M et al (2015).Clinical utility of tadalafil in the treatment of pulmonary arterial hypertension: an evidence-based review.
6. Guazzi M, Samaja M (2007). The role of PDE5-inhibitors in cardiopulmonary disorders: from basic evidence to clinical development.
7. Martyn-St James, Marrissa et al (2017). Phosphodiesterase Type 5 Inhibitors for Premature Ejaculation: A Systematic Review and Meta-analysis.
8. Xu Y, et al (2014). Meta-analysis of clinical efficacy of sildenafil, a phosphodiesterase type-5 inhibitor on high altitude hypoxia and its complications. 
9. Cohen DJ, Glina S (2015). Penile rehabilitation after radical prostatectomy. 
10. Ferrini MG, et al (2018) Effect of ginger, Paullinia cupana, muira puama and l- citrulline, singly or in combination, on modulation of the inducible nitric oxide- NO-cGMP pathway in rat penile smooth muscle cells.