Sildenafil vs vardenafil

Sildenafil (the generic of Viagra) and vardenafil (the generic of Levitra) are close cousins. Both block the PDE5 enzyme so more blood can flow into the penis when you’re aroused, both are taken about an hour before sex, both reach their peak at a median of 60 minutes, and both last around 4 to 5 hours. Neither works without sexual stimulation.

The real differences are smaller and more practical: dose sizes, how a heavy meal affects them, a heart-rhythm warning on vardenafil, and availability. Sildenafil is sold by most online ED providers for a few dollars a dose. Outside compounded versions, vardenafil is listed by only two of the providers we compare, and the Levitra brand is discontinued.

Timing and duration

These figures are from each drug’s FDA label.

The sildenafil label allows a dose anywhere from 30 minutes to 4 hours before sex. The vardenafil label says it may be taken with or without food, but its own studies found that a high-fat meal cut the peak level by 18% to 50%. In practice, both work best if you don’t take them straight after a big, fatty meal.

For a drug with a much longer window, see how long Cialis lasts: tadalafil worked up to 36 hours after a dose in its trials.

Doses

Vardenafil’s doses are smaller in milligrams, which says nothing about which drug works better. Older men clear both more slowly: in men 65 and over, sildenafil exposure was about 84% higher and vardenafil exposure 52% higher than in young men, which is why both labels suggest a lower first dose. The vardenafil label also says not to use it in men on kidney dialysis.

How well they work

The labels report results in different ways and no head-to-head trial is reported in either, so the numbers below can’t be compared directly. They show that both drugs work for most men.

Sildenafil. In four fixed-dose trials of 1,797 men lasting 12 to 24 weeks, 63% on 25 mg, 74% on 50 mg and 82% on 100 mg reported improved erections, against 24% on placebo. In a trial in men with diabetes, 57% reported improvement against 10% on placebo.

Vardenafil. In the main North American trial of 762 men, the share of attempts in which men kept an erection long enough for successful sex was 51% on 5 mg, 64% on 10 mg and 65% on 20 mg at 3 months, against 32% on placebo. In men with diabetes it was 49% on 10 mg and 54% on 20 mg, against 23%; after prostate surgery, 37% and 34%, against 10%.

Side effects

Side effects from each label’s placebo-controlled trials, with sildenafil from its flexible-dose studies (the way it is usually prescribed):

Scroll sideways to see the full table

The profiles are very similar. Sildenafil more often causes brief vision changes, mostly a color tinge, light sensitivity or blurring. Vardenafil more often causes a stuffy or runny nose. Both labels note that some side effects become more common at higher doses.

The heart-rhythm warning on vardenafil

Vardenafil’s label has a warning sildenafil’s doesn’t. In a study of healthy men, a 10 mg dose and an 80 mg dose of vardenafil lengthened the QT interval on an ECG about as much as the antibiotic moxifloxacin. The label says men with congenital QT prolongation, and men taking class IA antiarrhythmics (such as quinidine or procainamide) or class III antiarrhythmics (such as amiodarone or sotalol), should avoid vardenafil. If you have a heart-rhythm condition or take heart-rhythm medicine, sildenafil or tadalafil may suit you better.

The serious warnings they share are the same as for every PDE5 inhibitor. Never take either with nitrates or with riociguat, because blood pressure can drop dangerously. Don’t combine them with each other or with another ED drug. Get emergency care for an erection lasting more than 4 hours, and stop and call a clinician for sudden loss of vision or hearing.

Brands and availability

Viagra was approved in March 1998 and is still sold, alongside many generics. Levitra was approved on August 19, 2003, and Staxyn, a version that dissolves in the mouth, in June 2010. Drugs@FDA now lists both vardenafil brands as discontinued; generic vardenafil tablets are still approved.

Online, that gap is wide. Most ED providers we compare sell generic sildenafil tablets. For vardenafil, Lemonaid lists it among the generic ED drugs it prescribes without a separate price, and RxSpan MD charges $149 a month without stating the strength, the number of doses or whether it is compounded, as of October 2026.

You’ll also see compounded vardenafil, such as BlueChew’s chewable tablets (from $4.34 each) and Maximus’ compounded vardenafil (from $59.99 a month). These are not Levitra and not a generic of it: a pharmacy compounds them and they aren’t FDA-approved. See our page on compounded ED chewables.

What each costs online

Generic prices on each provider’s own site, October 2026:

Generic sildenafil runs $1.60 to $6.25 a dose at the providers that publish a regular per-dose price. See where generic sildenafil is cheapest for the terms behind each one.

Which to choose

• Choose sildenafil for the widest choice of providers, the lowest price per dose and the longest track record.
• Consider vardenafil if sildenafil’s vision side effects bother you or a clinician suggests trying another PDE5 inhibitor, and you have no heart-rhythm condition. Expect fewer places to get it.
• Consider tadalafil if you want a longer window or a daily option. Our sildenafil vs tadalafil guide compares the two.

The bottom line

Sildenafil and vardenafil work the same way on almost the same clock: about an hour to peak and around 4 to 5 hours of effect, with headache and flushing as the main side effects. Vardenafil comes in smaller doses, carries a QT-prolongation warning and is much harder to find online since Levitra was discontinued. As of October 2026, generic sildenafil costs $1.60 to $6.25 a dose. Compare providers in our sildenafil rankings, the ED rankings or on the ED hub.