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

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.

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.

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.

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.

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.