The best ED pills: sildenafil, tadalafil, vardenafil and avanafil

There is no single best ED pill. The four the FDA has approved, sildenafil, tadalafil, vardenafil and avanafil, all work the same way: they block an enzyme called PDE5, which lets blood flow into the penis more easily when you are aroused. None of them causes an erection on its own, and none of them changes desire. What separates them is timing, how food affects them, their side effects and their price.

This guide compares the four on those points, using their FDA labels and the prices online providers published in October 2026. For the providers themselves, see our best online ED providers.

The four pills at a glance

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All four are taken no more than once a day.

Sildenafil: the cheapest and most studied

Sildenafil, the drug in Viagra, was approved in 1998 and is the ED pill most men start on. You take it about an hour before sex, at 50 mg for most men, adjusted to 25 mg or 100 mg by how well it works and how you tolerate it. Men over 65 and men taking alpha-blockers may start at 25 mg.

In the label’s four 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. Peak levels arrive in a median of about an hour, and a high-fat meal pushes that back by about another hour and lowers the peak by 29%, so it works best on a light stomach. See how long Viagra lasts.

Generic sildenafil is also the cheapest ED pill online: $1.60 to $6.25 a dose at the providers we track, taking each one’s lowest regular price, or $16 to $195 a month on monthly plans with any required membership included, as of October 2026. Compare providers on our generic sildenafil list and read about sildenafil.

Tadalafil: the long window, or a daily pill

Tadalafil, the drug in Cialis, has a half-life of about 17.5 hours against about 4 for sildenafil, which is why one dose can work for a day and a half. In a trial of 348 men taking 20 mg, 61% had successful sex 22 to 26 hours after a dose and 64% at 33 to 39 hours, against 37% on placebo. Food doesn’t change how it is absorbed.

It is the only one of the four that also comes as a daily pill. At 2.5 mg or 5 mg once a day, it keeps a steady level so you don’t have to plan around a dose, and 5 mg a day is also approved for the urinary symptoms of an enlarged prostate. As needed, the usual dose is 10 mg, adjusted to 5 mg or 20 mg.

Back pain and muscle aches are more common with tadalafil than with the others; they usually start 12 to 24 hours after a dose and fade within a couple of days. Daily generic tadalafil costs $40 a month at the providers that sell it as a monthly plan, as of October 2026. See daily tadalafil providers, tadalafil and our sildenafil vs tadalafil guide.

Vardenafil: like sildenafil, less common online

Vardenafil works on a similar timetable to sildenafil: most men take 10 mg about an hour before sex, adjusted to 5 mg or 20 mg, and men 65 and older may start at 5 mg. In its four 3-month trials of 2,431 men, including men with diabetes and men after prostate surgery, 5 mg, 10 mg and 20 mg each improved erectile function scores more than placebo.

The Levitra brand and the dissolving Staxyn tablet are listed as discontinued at Drugs@FDA, but generic vardenafil tablets are still made. Two cautions are specific to it: it can prolong the QT interval on an ECG, so tell your clinician about heart-rhythm problems or heart-rhythm medicines, and some drug interactions cap the dose at 2.5 mg or 5 mg.

Few online providers sell it. The providers we track don’t publish a price for generic vardenafil tablets; BlueChew and Maximus sell compounded vardenafil, which isn’t FDA-approved. See vardenafil.

Avanafil: the fastest start

Avanafil, sold as Stendra and approved in 2012, is labeled to work as early as about 15 minutes after a 100 mg or 200 mg dose, or about 30 minutes after 50 mg. Men on alpha-blockers start at 50 mg. In its trials of 2 to 3 months, doses of 50 mg to 200 mg improved erectile function scores over placebo, and one trial measured success starting about 15 minutes after a dose.

Its peak levels arrive 30 to 45 minutes after a dose on an empty stomach; a high-fat meal delays that by a little over an hour and lowers the peak by 39%. A generic avanafil tablet is listed on DailyMed, but none of the online providers we track publishes an avanafil price. See avanafil.

Side effects and who shouldn’t take them

The common side effects are shared: headache, flushing, a stuffy nose and indigestion. Sildenafil can cause a blue tinge or blurred vision for a few hours, and tadalafil back and muscle pain.

The serious warnings are shared too. Never take any of them with a nitrate for chest pain, in any form including “poppers”, or with riociguat, because the combination can drop blood pressure dangerously. Alpha-blockers, other blood pressure medicines and heavy drinking can lower it as well. Get emergency care for an erection lasting more than 4 hours, and stop and call a clinician for sudden loss of vision or hearing. Ask a clinician whether your heart is healthy enough for sex before you start.

Brand-name or generic?

FDA-approved generic sildenafil and tadalafil come in the same strengths as Viagra and Cialis and are approved for the same uses; the FDA requires a generic to deliver the same amount of drug to the body as the brand. The difference is price. As of October 2026, brand-name Viagra costs $96 to $139 a dose at the online providers that sell it, against $1.60 to $6.25 for generic sildenafil. See brand-name Viagra and Cialis online.

Chewables and dissolving tablets sold online are a third category: they are compounded, which means a pharmacy prepares them for your prescription, and they are not Viagra or Cialis, not generics of them, and not FDA-approved. In September 2025 the FDA sent warning letters to telehealth sellers of compounded ED products, including BlueChew and Hello Cake, over how the products were marketed. See ED chewables and Hims vs BlueChew.

How to choose

• You want the lowest price: generic sildenafil.
• You want a dose that covers a day and a half, or not to plan at all: tadalafil, as needed or daily.
• You want the shortest wait: avanafil, if you can find a provider that prescribes it.
• Sildenafil works but its side effects bother you: ask about vardenafil or tadalafil.
• You also have urinary symptoms from an enlarged prostate: daily tadalafil 5 mg treats both.

A clinician can switch you between pills if the first doesn’t suit you; don’t take two together.

The bottom line

All four FDA-approved ED pills work, and none is stronger in a way that matters for choosing. Pick by timing and price: generic sildenafil is the cheapest at $1.60 to $6.25 a dose online as of October 2026, tadalafil lasts longest and comes as a daily pill, avanafil starts fastest, and vardenafil is an alternative if the others don’t suit you. Compare providers on our ED rankings or start from the ED hub.