What Is Sildenafil Used For?

Kristin Hall, FNP

Medically reviewed by Kristin Hall, FNP

Written by Our Editorial Team

Last updated 4/13/2021

Sildenafil, the active ingredient in Viagra®, is a common medication that’s used to treat erectile dysfunction (ED) and pulmonary arterial hypertension (PAH).

If you’ve been diagnosed with erectile dysfunction, your healthcare provider may prescribe you sildenafil to improve your erections and sexual performance. 

If you’re affected by pulmonary arterial hypertension, your healthcare provider may recommend sildenafil on its own or with other medication to lower blood pressure in your lungs and improve your lung function. 

Sildenafil is one of several erectile dysfunction medications in use today. It’s a fast-acting drug that, for most people, is safe and effective. However, like other medications, it can cause side effects and has several interactions that you should be aware of before use.

Below, we’ve explained what sildenafil is and what it’s typically used for. We’ve also discussed alternatives to sildenafil, including several other medications that are available to treat erectile dysfunction. 

Sildenafil: The Basics

  • Sildenafil belongs to a class of medications called phosphodiesterase type 5 inhibitors, or PDE5 inhibitors. It comes in tablet form and requires a prescription.

  • Medications like sildenafil work by causing the smooth muscle of your vascular system to relax. This improves blood flow in certain parts of your body and reduces your blood pressure levels.

  • Sildenafil is sold as a generic medication and under several brand names. You may have heard of sildenafil under the brand names Viagra or Revatio®.

  • The most common uses for sildenafil include treating erectile dysfunction and pulmonary arterial hypertension, a form of high blood pressure that affects the blood vessels inside your lungs.

  • Sildenafil is one of several medications available to treat ED. Others include tadalafil (the active ingredient in Cialis®), vardenafil (Levitra®) and avanafil (Stendra®).

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Sildenafil for Erectile Dysfunction (ED)

Sildenafil is best known as a treatment for erectile dysfunction, or ED. Originally sold under the brand name Viagra, sildenafil came onto the market in 1998 as the first mainstream medication for treating ED and improving sexual performance in men. 

Erectile dysfunction is a common issue that affects men of all ages and backgrounds. According to the National Institute of Diabetes and Digestive and Kidney Diseases, about 30 million men in the United States are affected by ED.

As an ED treatment, sildenafil works by increasing blood flow to the erectile tissue found inside your penis. 

Erections are all about healthy blood flow. When you feel sexually aroused, impulses from your brain and local nerves around your penis signal to the muscles that control blood flow into your corpora cavernosa -- the pair of cylinder-shaped areas of erectile tissue in your penis.

As these muscles relax, blood starts to flow into your penis, creating pressure that increases its size and makes it feel firmer to the touch.

In order to keep your penis firm during sex, the tunica albuginea -- a fibrous covering that wraps around the corpora cavernosa -- contracts. This traps the blood inside your penis and sustains your erection until you reach orgasm and ejaculate.

By dilating the arteries that supply blood to your penis, sildenafil makes it easier for this process to take place, helping you to get and sustain an erection during sex. 

It’s worth noting that sildenafil won’t cause you to feel aroused without any stimulation, nor will it give you an erection if you’re not in the mood for sex. Its effects are purely physical and there is no evidence that it affects your sex drive in any meaningful way. 

Interestingly, sildenafil wasn’t initially developed as a treatment for erectile dysfunction. Instead, it was under investigation as a treatment for hypertension and angina. During testing, the team studying sildenafil noticed that it often caused erections as a side effect.

Today, sildenafil is still available as Viagra. It’s also available as a generic medication for erectile dysfunction. As a treatment for ED, sildenafil is available in a range of different dosages from 25 to 100mg.

Alternatives to Sildenafil for Erectile Dysfunction

Sildenafil is a fast-acting, convenient medication for treating erectile dysfunction. On average, it starts working in approximately 30 minutes and provides relief from ED for about four hours per dose.

In addition to sildenafil, several other medications are available to treat erectile dysfunction:

  • Tadalafil. The active ingredient in Cialis, tadalafil is a long-lasting ED medication that can provide relief from erectile dysfunction for up to 36 hours per dose.

  • Vardenafil. The active ingredient in Levitra, vardenafil has similar effects to sildenafil and typically lasts for approximately four hours per dose.

  • Avanafil. Available as Stendra, avanafil is a second-generation PDE5 inhibitor that’s less likely to cause certain side effects than older ED medications. 

You can learn more about these medications and how they work in our full guide to the most common erectile dysfunction treatments and drugs

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Sildenafil for Pulmonary Arterial Hypertension (PAH)

Although sildenafil is best known as a medication for erectile dysfunction, it’s also used to treat a condition called pulmonary arterial hypertension, or PAH.

Pulmonary arterial hypertension is a condition in which the small arteries in your lungs become thicker. This reduces the ability of blood to flow through your lungs and causes an increase in blood pressure.

Over time, pulmonary arterial hypertension tends to worsen, affecting your cardiovascular health and overall wellbeing.

Unlike erectile dysfunction, pulmonary arterial hypertension isn’t very common. According to the American Lung Association, only around 500 to 1,000 cases of PAH are diagnosed in the United States every year.

Sildenafil is one of several medications used to treat PAH. It works by helping the blood vessels in the lungs to relax and widen, reducing blood pressure and improving blood flow between the lungs and heart.

As a treatment for PAH, sildenafil is typically prescribed in a 20mg dosage. It’s available under a variety of brand names, including Revatio and others. 

Sildenafil Side Effects & Interactions

Sildenafil (generic Viagra) is used by millions of men of all ages and backgrounds. Although it’s generally a safe, effective medication, it can cause certain side effects and interactions, whether it’s used to treat erectile dysfunction or pulmonary arterial hypertension. 

Common side effects of sildenafil include:

  • Headache

  • Flushing

  • Dyspepsia (indigestion)

  • Abnormal vision

  • Nasal congestion

  • Back pain

  • Myalgia (muscle pain)

  • Nausea

  • Dizziness

  • Rash

Most side effects caused by sildenafil are minor and temporary, meaning they should gradually fade away as the medication leaves your body.

Although uncommon, sildenafil may also cause other side effects, including hearing issues and priapism (painful, persistent erections). We’ve discussed these in more detail in our full guide to Viagra (sildenafil) side effects.

In addition to causing side effects, sildenafil and other PDE5 inhibitors may interact with certain medications used to treat high blood pressure and other cardiovascular health conditions. Specifically, nitrates may cause a significant and sudden drop in blood pressure, which may result in feeling dizzy, faint or even in a heart attack or stroke. 

Before using sildenafil, make sure to inform your healthcare provider about any medications you currently use or have recently used. 

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In Conclusion

Sildenafil is most commonly prescribed to treat erectile dysfunction. As a fast-acting drug, it can produce a noticeable improvement in your sexual function and provide relief from ED for as long as four hours per dose. 

In addition to treating ED, sildenafil is one of several medications prescribed to treat pulmonary arterial hypertension, or PAH. 

Currently, sildenafil is only available with a prescription. We offer sildenafil online as a treatment for erectile dysfunction, following a consultation with a healthcare provider who will determine if a prescription is appropriate. 

8 Sources

Hims & Hers has strict sourcing guidelines to ensure our content is accurate and current. We rely on peer-reviewed studies, academic research institutions, and medical associations. We strive to use primary sources and refrain from using tertiary references.

  1. Dhaliwal, A. & Gupta, M. (2020, June 23). PDE5 Inhibitor. StatPearls. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK549843/
  2. Definition & Facts for Erectile Dysfunction. (2017, July). Retrieved from https://www.niddk.nih.gov/health-information/urologic-diseases/erectile-dysfunction/definition-facts
  3. Erection Ejaculation: How It Occurs. (2020, November 27). Retrieved from https://my.clevelandclinic.org/health/articles/10036-erection-ejaculation-how-it-occurs
  4. VIAGRA® (sildenafil citrate) tablets, for oral use. (2014, March). Retrieved from https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/020895s048lbl.pdf
  5. Eardley, I., Ellis, P., Boolell, M. & Wulff, M. (2002, February). Onset and duration of action of sildenafil for the treatment of erectile dysfunction. British Journal of Clinical Pharmacology. 53(Suppl 1), 61S–65S. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1874251/
  6. Learn About Pulmonary Arterial Hypertension. (n.d.). Retrieved from https://www.lung.org/lung-health-diseases/lung-disease-lookup/pulmonary-arterial-hypertension/learn-about-pulmonary-arterial-hypertension
  7. Sildenafil (Revatio®). (2013, November). Retrieved from https://phassociation.org/patients/treatments/sildenafil/
  8. REVATIO (sildenafil) tablets, for oral use. (2014, March). Retrieved from https://www.accessdata.fda.gov/drugsatfda_docs/label/2014/021845s011,022473s004,0203109s002lbl.pdf

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment. Learn more about our editorial standards here.