Sildenafil is the active ingredient in Viagra. They are the same drug. Viagra is simply the brand name that Pfizer gave to sildenafil citrate when it launched in the late 1990s, much like Tylenol is the brand name for acetaminophen. Every Viagra tablet ever made contains sildenafil as its sole active ingredient.
Why You See Both Names
When Pfizer developed the drug, it patented the compound sildenafil citrate and marketed it under the brand name Viagra. Once that patent expired (in 2013 in the UK, and shortly after in the US), other manufacturers gained the right to produce and sell the same compound. These versions are labeled “sildenafil” rather than “Viagra” because only Pfizer owns the Viagra trademark. Pfizer even launched its own generic through a subsidiary called Greenstone, selling it simply as sildenafil citrate.
So when you see a prescription for “sildenafil,” it’s the generic version of Viagra. The active molecule entering your bloodstream is identical.
How Generic Sildenafil Differs From Brand Viagra
The active ingredient and its dose are the same, but the pills look different. Brand-name Viagra comes as a recognizable blue, diamond-shaped tablet in 25 mg, 50 mg, or 100 mg strengths. Generic sildenafil tablets vary widely depending on the manufacturer. They can be white, green, or blue, and come in round, oval, or oblong shapes with different imprint codes stamped on them.
The inactive ingredients (fillers, coatings, and dyes that hold the pill together) can also differ between manufacturers. These ingredients don’t affect how the drug works for the vast majority of people, though someone with a rare allergy to a specific dye or filler might need to check the label. The FDA requires generics to deliver the same amount of active drug into the bloodstream within a tight range of the brand-name version, so therapeutic performance is equivalent.
The Price Gap Is Significant
The biggest practical difference between brand Viagra and generic sildenafil is cost. Without insurance, brand-name Viagra runs roughly $85 per pill at the 100 mg strength. Generic sildenafil at the same dose can cost as little as $0.12 per pill at the lowest end, though pricing varies by pharmacy and quantity. Even when Pfizer first introduced its own authorized generic in 2017, it priced it at $30 to $35 per pill, about half the brand-name cost at that time. Today, with multiple generic manufacturers competing, prices have dropped far further.
Because the active drug is identical, most prescribers write for generic sildenafil unless a patient specifically requests the brand. Insurance plans that cover the medication almost always favor the generic as well.
Sildenafil Has a Second, Different Use
Here’s where it gets slightly more complicated. Sildenafil is also sold under a completely separate brand name, Revatio, for treating pulmonary arterial hypertension, a condition involving dangerously high blood pressure in the lungs. Revatio is a small, round, white 20 mg tablet, visually distinct from Viagra’s blue diamond shape. The FDA approved it for this purpose in 2005.
The drug works the same way in both cases: it relaxes blood vessels by blocking an enzyme that restricts blood flow. In erectile dysfunction, that relaxation increases blood flow to the penis. In pulmonary hypertension, it eases pressure in the arteries of the lungs. The difference is the dose (20 mg for lung conditions versus 25 to 100 mg for erectile dysfunction) and the prescribing context. Viagra is not approved for pulmonary hypertension, and Revatio is not approved for erectile dysfunction, even though the molecule inside both is sildenafil citrate.
What This Means for Your Prescription
If your pharmacy fills a Viagra prescription with generic sildenafil, you’re getting the same drug at a lower price. The tablet will look different, but the clinical effect is the same. If you’re picking up sildenafil 20 mg tablets, that’s the pulmonary hypertension dose, though some prescribers write it this way for erectile dysfunction and instruct patients to take multiple tablets. The strength on the label and the condition it’s prescribed for are what matter, not whether the box says Viagra or sildenafil.
In short: sildenafil is Viagra. Viagra is sildenafil. One is a chemical name, the other is a brand name, and the pill inside does exactly the same thing.