Sildenafil vs Tadalafil vs Vardenafil: Which PDE5 Inhibitor Lasts Longest?

Same family, different clock

All four medicines are PDE5 inhibitors. They do the same job — keep cGMP around so an erection can build during arousal — but their chemical structures give them different half-lives, and that changes how you use them.

• Sildenafil (Viagra, Kamagra) — the original. Onset in about 30–60 minutes, effect window around 4 hours. Food, especially fatty food, delays it.
• Tadalafil (Cialis) — the long one. Effect window up to roughly 36 hours, so it suits couples who don’t want to plan around a tablet. It is also approved as a small daily dose.
• Vardenafil (Levitra) — close to sildenafil in timing, with a similar 4–5 hour window.
• Avanafil (Spedra) — the fastest, with onset in as little as 15 minutes for some users and a window of about 6 hours.

The real question is lifestyle, not pharmacology

Choosing is usually less about “which is stronger” and more about when you expect to have sex:

• Planned, same-evening sex → sildenafil or vardenafil.
• Spontaneous sex across a weekend → tadalafil.
• As-fast-as-possible onset → avanafil.

None of the four is universally “better”; each optimises a different variable.

Food and alcohol affect them differently

Sildenafil and vardenafil are slowed by a heavy or fatty meal. Tadalafil and avanafil are much less affected. Alcohol is a problem for all of them, because it is a depressant that blunts arousal and lowers blood pressure.

What this means for Kamagra

Kamagra is sildenafil, so it inherits sildenafil’s profile: a roughly 4-hour window, slowed by heavy meals, and the classic nitrate warning. If you want the long-acting freedom of tadalafil, Kamagra is simply the wrong molecule — no formulation of it changes that.

Primary sources

1. 01
   NHS: Sildenafil (Viagra)

   Sildenafil dosing and cautions.

2. 02
   NHS: Tadalafil

   Tadalafil dosing and duration.