FREE ONLINE ED ASSESSMENT. Start Here

Viagra® vs. Sildenafil: What's the Difference?

Mike Bohl, MD, MPH, ALM

Reviewed by Mike Bohl, MD

Written by Geoffrey C. Whittaker

Published 05/15/2018

Updated 01/31/2024

If you’ve searched the web for information about ED medication, you’ve no doubt seen Viagra mentioned alongside a drug called sildenafil. And you might be wondering if there’s a difference between the two pharmaceuticals, given how often they’re interchanged.

The Viagra sildenafil generic question can be a little confusing — especially when you start trying to make sense of all the other names for Viagra, Cialis and other ED medications. 

The confusion is completely understandable.

Instead, we prefer to rephrase the question into two: “what is generic for Viagra?” and “what is brand name sildenafil?” Viagra is the brand name version of sildenafil that’s FDA approved for ED, and sildenafil is the main active ingredient in Viagra.

So, is sildenafil Viagra? Yes — but not always. Want to understand the nuances of this modern “the-chicken-or-the-egg” scenario? Let’s dig into the basics.

Choose your chew

Add a boost to your sex life with our new chewable formats

Sildenafil citrate (often shortened to “sildenafil”) is the main ingredient in Viagra. After parent company Pfizer’s patent expired, other manufacturers were allowed to manufacture generic Viagra under the name of its generic ingredient, sildenafil. The terms are pretty much interchangeable, the way you might say “Kleenex®” to refer to a tissue. The only real difference between the two when used for ED is how much they cost.

Viagra® is a well-known and widely used medication for treating erectile dysfunction (ED), with the longest history of any FDA-approved ED treatment on the market today. Both generic sildenafil and Viagra work by increasing the level of blood flow to your penis, making it easier for you to get and maintain an erection

Sildenafil belongs to a class of enzyme-inhibiting drugs called phosphodiesterase type 5 inhibitors, or PDE5 inhibitors. Like the others in its class, sildenafil works by relaxing the muscle tissue inside the walls of your blood vessels, improving blood flow throughout some parts of your body — including your penis.

It's important to note that these erectile dysfunction medications aren't wonder drugs. They only work if you're sexually stimulated. But if you’ve got sexual stimulation and these pills, research shows that you have an effective, reliable erectile dysfunction treatment.

If you’re curious about the history of the brand and generic names, here’s the quick version:

  • In 1996, Pfizer patented sildenafil. 

  • Two years and many clinical trials later, in March of 1998, the new medication — now called Viagra — received approval from the Food and Drug Administration and hit the market as a prescription medication used to treat erectile dysfunction.

  • As the first oral medication for erectile dysfunction, Viagra became incredibly popular. Its blue color and diamond shape earned it the nickname the “little blue pill” and large-scale TV ad campaigns made it a medication that just about everyone knew about.

  • In 2005, sildenafil was approved by the FDA under the brand name Revatio® for the treatment of pulmonary arterial hypertension — more on this later.

  • Pfizer’s patent on Viagra expired in 2012 for countries outside the US, allowing other brands to produce and market their own generic Viagra medications containing sildenafil. 

  • Although Pfizer challenged the expired patent in the United States, sildenafil has since become widely available as a generic medication that is manufactured and marketed by a range of different companies.

Choose your chew

Add a boost to your sex life with our new chewable formats

Viagra is brand-name sildenafil that’s FDA approved for ED, and what is the active ingredient in Viagra? Sildenafil. But we suspect the question you really want to ask is whether one is made better, or safer — is generic sildenafil as good as Viagra for treating ED?

Although some manufacturers may use their own brand name, most generic sildenafil products are labeled simply as “sildenafil.” Regardless, they do the same thing, offer the same benefits and come with the same risk of side effects. 

Their primary difference is their price.

While a single tablet of Viagra is priced as high as $70 in the United States, generic drugs like sildenafil tablets are available for as little as $3 each when purchased online.

Even though there’s no difference in active ingredients, if you’re switching from Pfizer’s brand name Viagra to a generic form of sildenafil, it’s important to check that you’re purchasing tablets with a similar dosage to the one your healthcare provider prescribed.

Viagra comes in three dosages: 25mg, 50mg and 100mg. Most patients start at 50mg.

Sildenafil pills similarly come in 25mg, 50mg, and 100mg tablets. However, sildenafil can also come in 20mg tablets when they are the generic version of Revatio. Revatio is FDA approved to treat a type of high blood pressure in the lungs (called pulmonary arterial hypertension, or PAH), but it can be prescribed off label for ED.

While each tablet of generic Revatio is 20mg, when used for ED, you could be prescribed multiple tablets at once, making 40mg, 60mg, 80mg and 100mg doses possible. Learn more about the difference between Revatio® and Viagra on our blog. Sildenafil is also available in the United States as a liquid solution.

Your healthcare provider will tell you the specific dosage of brand name Viagra or generic sildenafil that you should use if you’re prescribed this medication. 

Since brand name Viagra tablets and generic sildenafil both contain the exact same active ingredient, you can expect identical results from a 25mg-100mg dose of Viagra (the typical doses used for erectile dysfunction) to the same dose of generic sildenafil.

Both Viagra and sildenafil work best when taken at least 30 minutes to an hour before sexual activity (and no more than four hours beforehand). 

You can take Viagra or generic sildenafil with or without food, but should avoid taking either with a high-fat meal, as it can make both medications take longer to take effect in your body.

If you don’t experience any improvement in your erectile function after using Viagra or generic sildenafil, don’t simply take more of this medication. Instead, let your healthcare provider know — they may recommend adjusting your dosage or trying a different ED medication. Although sildenafil works similarly to other PDE5 inhibitors like vardenafil (Levitra), they have different dosages. Vardenafil, for example, uses a lower dose, although not necessarily stronger than Viagra.

Choose your chew

Since brand name Viagra and generic sildenafil contain the same active ingredient and come in the same range of dosages, both medications can cause an identical range of side effects. 

We’ve broken them down into two groups: common and serious. We’ve also shared a note about serious drug interaction risks that you should seek to avoid and alert your healthcare provider to before taking sildenafil.

Common Side Effects of Viagra and Sildenafil

Common side effects of Viagra and generic sildenafil include:

  • Heartburn

  • Indigestion

  • Headache

  • Nosebleeds

  • Nasal congestion

  • Flushing

  • Diarrhea

  • Muscle aches

  • Increased sensitivity to light

  • Changes in your perception of color, such as a visible blue tinge or difficulty telling the difference between the colors blue and green

Most of these side effects resolve on their own as the medication leaves your body. 

Rare Side Effects of Viagra and Sildenafil

In rare cases, Viagra and generic sildenafil may cause serious side effects, such as:

  • Priapism (a persistent, often painful erection lasting longer than four hours)

  • Sudden blurred vision

  • Loss of vision

  • Lightheadedness and dizziness (typically brought on by low blood pressure when combined with other medications)

If you experience any of these severe side effects, seek medical attention immediately.

Viagra and Sildenafil Drug Interactions

Both Viagra and generic sildenafil can interact with other medications, including alpha-blockers, nitrates and other medications used to treat hypertension (high blood pressure), heart disease and other cardiovascular health issues.

As such, you’ll want to tell your healthcare provider if you’re taking any prescription or over-the-counter medications, or if you’ve had previous heart issues like angina, chest pain or a heart attack.

Our complete guide to Viagra (sildenafil) side effects discusses the side effects and interactions listed above in more detail.

Sildenafil citrate

Get hard for 95% cheaper than Viagra

Minor differences in packaging and pill appearance aside, brand name Viagra and its generic counterpart sildenafil are exactly the same medication. 

If you have erectile dysfunction, both medications should produce noticeable improvements in your erections and sexual performance. The key difference, as we mentioned above, is price. While Viagra is relatively expensive, you can purchase generic sildenafil tablets at a much more affordable price.

In addition to sildenafil and Viagra, we offer other proven ED medications online including:

  • Tadalafil (Cialis®) can provide relief from erectile dysfunction for up to 36 hours per dose.

  • Vardenafil(Levitra®) offers relief from ED for slightly longer than sildenafil.

  • Avanafil (Stendra®) works quickly and is less likely to cause certain side effects. 

You can learn more about these medications in our complete guide to the best pills for treating erectile dysfunction or access our selection of FDA-approved ED medications online.

Related Articles

5 Sources

  1. accessdata.fda.gov (n.d) Label: Viagra (sildenafil citrate) tablets. Retrieved from: https://www.accessdata.fda.gov/drugsatfda_docs/label/2014/20895s039s042lbl.pdf
  2. Ferguson, J. E., 3rd, & Carson, C. C., 3rd (2013). Phosphodiesterase type 5 inhibitors as a treatment for erectile dysfunction: Current information and new horizons. Arab journal of urology, 11(3), 222–229. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4443003/
  3. Gurtner, K., Saltzman, A., Hebert, K., & Laborde, E. (2017). Erectile Dysfunction: A Review of Historical Treatments With a Focus on the Development of the Inflatable Penile Prosthesis. American journal of men's health, 11(3), 479–486. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5675239/.
  4. Drug approval package. Brand Name (Generic Name) NDA #. (n.d.). Retrieved March 29, 2023, from https://www.accessdata.fda.gov/drugsatfda_docs/NDA/98/viagra/viagra_toc.cfm.
  5. Center for Drug Evaluation and Research. (n.d.). Generic Drug Facts. U.S. Food and Drug Administration. Retrieved March 29, 2023, from https://www.fda.gov/drugs/generic-drugs/generic-drug-facts
Editorial Standards

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. See a mistake? Let us know at [email protected]!

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.

Mike Bohl, MD

Dr. Mike Bohl is a licensed physician, a Medical Advisor at Hims & Hers, and the Director of Scientific & Medical Content at a stealth biotech startup, where he is involved in pharmaceutical drug development. Prior to joining Hims & Hers, Dr. Bohl spent several years working in digital health, focusing on patient education. He has also worked in medical journalism for The Dr. Oz Show (receiving recognition for contributions from the National Academy of Television Arts and Sciences when the show won Outstanding Informative Talk Show at the 2016–2017 Daytime Emmy® Awards) and at Sharecare. He is a Medical Expert Board Member at Eat This, Not That! and a Board Member at International Veterinary Outreach.

Dr. Bohl obtained his Bachelor of Arts and Doctor of Medicine from Brown University, his Master of Public Health from Columbia University, and his Master of Liberal Arts in Extension Studies—Journalism from Harvard University. He is currently pursuing a Master of Business Administration and Master of Science in Healthcare Leadership at Cornell University. Dr. Bohl trained in internal medicine with a focus on community health at NYU Langone Health.

Dr. Bohl is Certified in Public Health by the National Board of Public Health Examiners, Medical Writer Certified by the American Medical Writers Association, a certified Editor in the Life Sciences by the Board of Editors in the Life Sciences, a Certified Personal Trainer and Certified Nutrition Coach by the National Academy of Sports Medicine, and a Board Certified Medical Affairs Specialist by the Accreditation Council for Medical Affairs. He has graduate certificates in Digital Storytelling and Marketing Management & Digital Strategy from Harvard Extension School and certificates in Business Law and Corporate Governance from Cornell Law School.

In addition to his written work, Dr. Bohl has experience creating medical segments for radio and producing patient education videos. He has also spent time conducting orthopedic and biomaterial research at Case Western Reserve University and University Hospitals of Cleveland and practicing clinically as a general practitioner on international medical aid projects with Medical Ministry International.

Dr. Bohl lives in Manhattan and enjoys biking, resistance training, sailing, scuba diving, skiing, tennis, and traveling. You can find Dr. Bohl on LinkedIn for more information.

Publications

  • Younesi, M., Knapik, D. M., Cumsky, J., Donmez, B. O., He, P., Islam, A., Learn, G., McClellan, P., Bohl, M., Gillespie, R. J., & Akkus, O. (2017). Effects of PDGF-BB delivery from heparinized collagen sutures on the healing of lacerated chicken flexor tendon in vivo. Acta biomaterialia, 63, 200–209. https://www.sciencedirect.com/science/article/abs/pii/S1742706117305652?via%3Dihub

  • Gebhart, J. J., Weinberg, D. S., Bohl, M. S., & Liu, R. W. (2016). Relationship between pelvic incidence and osteoarthritis of the hip. Bone & joint research, 5(2), 66–72. https://boneandjoint.org.uk/Article/10.1302/2046-3758.52.2000552

  • Gebhart, J. J., Bohl, M. S., Weinberg, D. S., Cooperman, D. R., & Liu, R. W. (2015). Pelvic Incidence and Acetabular Version in Slipped Capital Femoral Epiphysis. Journal of pediatric orthopedics, 35(6), 565–570. https://journals.lww.com/pedorthopaedics/abstract/2015/09000/pelvic_incidence_and_acetabular_version_in_slipped.5.aspx

  • Islam, A., Bohl, M. S., Tsai, A. G., Younesi, M., Gillespie, R., & Akkus, O. (2015). Biomechanical evaluation of a novel suturing scheme for grafting load-bearing collagen scaffolds for rotator cuff repair. Clinical biomechanics (Bristol, Avon), 30(7), 669–675. https://www.clinbiomech.com/article/S0268-0033(15)00143-6/fulltext

Read more