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

Kristin Hall, FNP

Medically reviewed by Kristin Hall, FNP

Written by Our Editorial Team

Last updated 5/18/2021

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.

If you’ve searched for information about ED medication before, you’ve no doubt seen Viagra mentioned alongside a drug called sildenafil. 

While these two medications might have different names, they’re actually the same active ingredient. 

The difference is that Viagra is a brand name medication invented and marketed by Pfizer, while sildenafil (or sildenafil citrate) is the generic name for the ingredient in Viagra that’s responsible for its positive effects on treating erectile dysfunction.

Viagra vs. Generic Sildenafil

Viagra and generic sildenafil work by increasing the level of blood flow to your penis, making it easier for you to get an erection. 

Sildenafil, which is the active ingredient in both medications, belongs to a class of drugs called phosphodiesterase-5 inhibitors, or PDE5 inhibitors

As a PDE5 inhibitor, sildenafil works by relaxing the muscle tissue that’s found inside the walls of your blood vessels, resulting in improved blood flow throughout many parts of your body.

Contrary to popular belief, drugs like Viagra and generic sildenafil won’t cause you to randomly get hard on their own. 

Instead, these medications work by making it easier to get an erection if you experience sexual stimulation.

Sildenafil has been available since 1998, when it was approved by the FDA under the product name Viagra as a medication for erectile dysfunction.

Interestingly, sildenafil was originally discovered while chemists at Pfizer were searching for a treatment for high blood pressure.

Thanks to its vasodilation effects, sildenafil initially looked like a promising treatment for angina -- a form of chest pain -- but the results weren’t strong enough to be worth studying further.

In some cases, sildenafil is still used today to treat pulmonary arterial hypertension (PAH) -- a form of high blood pressure that can affect the arteries of the lungs. 

Pfizer patented sildenafil in 1996. Two years later, in March of 1998, the new medication, now called Viagra, received approval from the FDA and went on sale 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 of the “little blue pill” and large-scale TV ad campaigns made it a medication that just about everyone knew about.

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 and can be manufactured and marketed by a range of different companies.

Although some manufacturers may use their own brand name, most generic sildenafil products are labeled simply as “sildenafil.”

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Viagra vs. Sildenafil Dosage

Today, sildenafil is available in a variety of forms. It’s most commonly sold in tablet form, with a typical dosage of 20mg, 25mg, 50mg or 100mg. 

It’s also available in the United States in liquid solution form. 

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

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

Both brand name Viagra and generic sildenafil work best when taken approximately one hour before sexual activity. 

You can take Viagra or generic sildenafil with or without food (but generally recommended to avoid taking Viagra with a high fat meal).

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.

Sildenafil is also sold under the brand name Revatio®. This version of the medication contains an identical active ingredient to Viagra and generic sildenafil, but is dosed slightly lower and is intended to be used as a treatment for pulmonary arterial hypertension rather than ED. If you want to learn more about the difference between Revatio® and Viagra, we have a guide for you.

Side Effects of Viagra vs. Sildenafil

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. 

Common side effects of Viagra and generic sildenafil include:

  • Heartburn

  • Indigestion

  • Headache

  • Nosebleeds

  • Nasal congestion

  • Flushing

  • Diarrhea

  • Muscle aches

  • Increased sensitivity to light

  • Numbness, or a burning or tingling sensation in your arms, legs, hands or feet

  • 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 are transient, meaning they’ll gradually fade away as the medication exits your body. 

In rare cases, Viagra and generic sildenafil may cause severe side effects, such as priapism (a persistent, often painful erection), sudden loss of vision or feelings such as lightheadedness or dizziness.

If you experience any severe side effects from either medication, it’s important to seek medical advice and assistance immediately. 

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.

When used at the same time, some of these medications may cause you to develop a very low blood pressure level. 

If you’re prescribed any other medication, it’s important to inform your healthcare provider about this before you use either brand name Viagra or generic sildenafil. 

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

Is There Any Difference Between Viagra and Sildenafil?

In practical terms, no. Other than the difference names used on the packaging, the brand name version of Viagra and the generic drug sildenafil are the exact same medication, 

Viagra is the brand name that’s used by Pfizer to market its version of sildenafil citrate. There is no chemical difference between the sildenafil that’s used in Pfizer’s branded Viagra tablets and the generic sildenafil that’s available from other manufacturers.

As a general rule, assuming the dosage is the same, you will experience the same effects from a generic sildenafil tablet as you will from a Viagra tablet.

It’s worth noting that Viagra comes in several different strengths, with 25mg, 50mg and 100mg tablets available. 

If you’re switching from Pfizer’s brand name Viagra to a generic form of sildenafil, check that you’re purchasing tablets with the same dosage as prescribed by your healthcare provider.

With this said, there’s a pretty significant difference between Viagra and generic sildenafil that you may have noticed. 

While a single tablet of Viagra can cost as much as $70 in the United States, generic sildenafil tablets are available for as little as $3 each when purchased online.

Other Medications for Erectile Dysfunction

Although Viagra may be the best-known medication for treating erectile dysfunction, it’s far from the only option available if you have ED. Other ED medications include:

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

  • Vardenafil. The active ingredient in Levitra®, vardenafil offers relief from ED for slightly longer than Viagra or generic sildenafil.

  • Avanafil. Sold under the brand name Stendra®, avanafil is a newer ED medication that works quickly and is less likely to cause certain side effects. 

We offer brand name and generic versions of several proven ED medications online, following a consultation with a healthcare provider who will determine if a prescription is appropriate.

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Which One Is Right For Me?

Minor differences in packaging 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.

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.

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.

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