There is no single "best" PDE5 inhibitor. There's only the best one for your situation — and the right choice depends on how you plan to use it, what side effects you can tolerate, and what you're willing to pay. Here's a clear-eyed comparison across the dimensions that actually matter.
The Quick Reference
| Factor | Sildenafil | Tadalafil | Vardenafil | Avanafil |
|---|---|---|---|---|
| Brand name | Viagra | Cialis | Levitra | Stendra |
| FDA approval | 1998 | 2003 | 2003 | 2012 |
| Onset | 30–60 min | 30–45 min | 25–30 min | 15–30 min |
| Duration | 4–6 hr | Up to 36 hr | 4–5 hr | 6–12 hr |
| Daily dosing? | No | Yes (2.5/5mg) | No | No |
| Food effect | Significant | Minimal | Significant* | Minimal |
| Generic cost/dose | $2–8 | $2–10 | $3–12 | $8–25 |
| PDE5 selectivity | Moderate | Moderate | Moderate | Highest |
*Vardenafil's ODT (orally disintegrating tablet) form is not affected by food.
Ranked by Speed
If you want the shortest possible wait between taking a pill and being ready, avanafil wins clearly. But the differences between the top three are measured in minutes — 15 vs. 25 vs. 30. The meaningful gap is between sildenafil (which can take a full hour to kick in for some men) and the rest of the field.
Real-world tip: take any PDE5 inhibitor on an empty stomach and the onset accelerates for all four. Food timing matters more than which molecule you choose.
Ranked by Duration
Tadalafil is in a league of its own here. A single 20mg dose on Friday evening covers the entire weekend. No other PDE5 inhibitor comes close. If spontaneity is important to you — if you don't want to plan sex around a pill's window — tadalafil is the default answer.
Daily low-dose tadalafil (2.5mg or 5mg) eliminates timing entirely. You take it every morning like a vitamin, and you're covered around the clock. None of the other three offer a daily protocol.
Ranked by Food Tolerance
A 600-calorie high-fat meal can reduce sildenafil's peak concentration by up to 29% and delay its onset. This is the single most common reason men report that "Viagra didn't work" — they took it after dinner.
If you want to take your medication with or after a meal without worrying, tadalafil or avanafil are the better choices. The vardenafil ODT is a clever workaround — it absorbs through the oral mucosa rather than the stomach, effectively sidestepping the food issue.
Ranked by Cost
Sildenafil and tadalafil generics are now commodity-priced. The volume of generic manufacturing has driven costs down dramatically since their patents expired. Vardenafil generics are slightly less commoditized, and avanafil generics are still building volume.
For daily tadalafil users, the per-dose cost drops further because the daily doses (2.5mg, 5mg) are cheaper than the on-demand dose (20mg).
Ranked by Side-Effect Profile
Avanafil's higher PDE5 selectivity translates to lower rates of flushing, headache, and visual disturbance in clinical trials. Tadalafil's unique side effect is back pain and myalgia (from PDE11 cross-reactivity), which some men find bothersome. Sildenafil has the broadest side effect profile, largely because its PDE6 cross-reactivity causes the well-known blue-vision phenomenon.
Individual responses vary enormously. Some men take 100mg sildenafil with zero side effects; others get a splitting headache from 50mg. The rankings reflect trial averages, not guarantees.
The Bottom Line
Most men should start with either sildenafil (cheapest, most data) or tadalafil (most flexible, longest duration). Switch to vardenafil if you want faster onset without avanafil's price premium, or to avanafil if side effects from the others are an issue. Work with your prescriber to find the right fit — the first one you try doesn't have to be the last.