PDE5 inhibitors (phosphodiesterase type 5 inhibitors) are a class of medications primarily used to treat erectile dysfunction (ED) and other conditions such as pulmonary arterial hypertension. These medications work by enhancing blood flow in specific areas of the body, particularly the penis, by relaxing blood vessel walls.
Phosphodiesterase type 5 (PDE5) inhibitors are a group of medications most commonly used to treat erectile dysfunction (ED). Their ability to improve symptoms of ED was discovered accidentally while researchers were examining their potential use for high blood pressure and angina.
ED is often considered the most common form of sexual dysfunction in men, and it becomes more common with age. It’s estimated that anywhere between 30 million to 50 million men in the United States deal with ED.
PDE5 inhibitors are often the first treatment option for people with ED caused by poor blood flow to the penis.
In this article, we break down the most common types of PDE5 inhibitors on the market. We also take a look at how they work, what they’re used for, and how much they cost.
How Do PDE5 Inhibitors Work?
- PDE5 is an enzyme found in the walls of blood vessels, particularly in the smooth muscle of the penis.
- During sexual arousal, nitric oxide (NO) is released in the body, leading to the production of cyclic guanosine monophosphate (cGMP), a molecule that relaxes smooth muscle and allows blood to flow into the penis, causing an erection.
- PDE5 breaks down cGMP, reducing blood flow and causing the erection to subside.
- PDE5 inhibitors block the action of PDE5, allowing cGMP to remain active longer and enhancing the ability to achieve and maintain an erection.
Common PDE5 Inhibitors
- Sildenafil (Viagra):
- Onset: 30–60 minutes.
- Duration: About 4–6 hours.
- Best taken on an empty stomach.
- Tadalafil (Cialis):
- Onset: 15–45 minutes.
- Duration: Up to 36 hours.
- Can be taken as a daily low-dose pill.
- Vardenafil (Levitra, Staxyn):
- Onset: 30–60 minutes.
- Duration: About 4–5 hours.
- Food has minimal effect on absorption.
- Avanafil (Stendra):
- Onset: 15–30 minutes.
- Duration: About 6–12 hours.
- Can be taken with or without food.
Uses of PDE5 Inhibitors
- Erectile Dysfunction (ED):
- Enhances the ability to achieve and maintain erections during sexual stimulation.
- Pulmonary Arterial Hypertension (PAH):
- Sildenafil and tadalafil are approved for reducing high blood pressure in the lungs.
- Benign Prostatic Hyperplasia (BPH):
- Tadalafil is also approved to treat urinary symptoms associated with BPH.
Precautions and Side Effects
- Common Side Effects:
- Headache, flushing, nasal congestion, indigestion, dizziness.
- Rarely, vision changes or hearing loss.
- Serious Side Effects:
- Priapism (prolonged erection), hypotension (low blood pressure), and heart-related complications in at-risk individuals.
- Contraindications:
- Should not be used with nitrates (e.g., nitroglycerin) or certain alpha-blockers due to the risk of severe hypotension.
- Caution is needed for those with heart disease, liver issues, or kidney dysfunction.
Important Notes
- PDE5 inhibitors do not cause spontaneous erections—they require sexual stimulation to work.
- Always consult a healthcare provider before use to ensure safety and suitability.
Which foods contain PDE5 inhibitors?
PDE5 inhibitors naturally occur in some herbs. These herbs are often sold in supplement form and marketed to treat ED or enhance male vitality.
The FDATrusted Source warns against dietary supplements for treating ED because many of these products contain undisclosed ingredients that may be harmful. The safety and effectiveness of these supplements also hasn’t been adequately studied.
Epimedium (horny goat weed)
Epimedium, commonly referred to as horny goat weed, is a flowering plant native to Eastern Asia.
The name horny goat weed comes from a legend of a Chinese goat herder who observed increased sexual activity in his herd after they ate the leaves of this plant.
Horny goat weed’s active ingredient is called icariin. It’s been suggested that icariin may inhibit PDE5, increase NO production in the penis, and have a number of possible benefits for ED. However, there are no long-term toxicity studies and there are no clinical trialsTrusted Source in humans.
Kaempferia parviflora (black ginger)
Kaempferia parviflora, also known as black ginger or Thai ginger, is a plant native to Thailand. Lab and animal studies have found that it may have moderate PDE5-inhibiting effects.
One small studyTrusted Source with 13 participants found that it may improve some parameters of ED in men age 50 to 70, but more research is needed to fully understand its potential benefits.
Tribulus terrestris
Tribulus terrestris is a leafy plant that grows in Europe, Asia, and Africa. Research has found that natural alkaloids in the plant may have PDE5-inhibiting effects.
A 2017 clinical trial found that Tribulus terrestris was able to significantly improve erectile function in men age 18 to 65 with moderate erectile dysfunction, and that it was generally well-tolerated.
Malculra pomifera (osage orange)
Isoflavones from the Malculra pomifera plant may have PDE5-inhibiting effects. Research has found that derivatives of these isoflavones may be a potential lead for future PDE5-inhibitor development.