Simple Explanation
Sildenafil blocks an enzyme (PDE5) that normally restricts blood flow to the penis. With PDE5 blocked, blood vessels relax and expand, allowing more blood flow when you're aroused. It doesn't create arousal — it makes the physical response easier once you are aroused.
Step by Step
1. You Take Sildenafil
The medication absorbs into your bloodstream within 30-60 minutes.
2. PDE5 Enzyme Gets Blocked
Sildenafil inhibits PDE5, an enzyme that breaks down cGMP (a molecule that relaxes blood vessels).
3. cGMP Levels Rise
With PDE5 blocked, cGMP accumulates when you become aroused, causing smooth muscle relaxation.
4. Blood Flow Increases
Relaxed blood vessels allow more blood to flow into the penis, enabling a firmer erection.
Important: It's Not Automatic
Sildenafil doesn't cause spontaneous erections. You still need sexual stimulation and arousal. The medication just makes the physical response easier when arousal happens.
Think of it like clearing a blocked pipe — the water still needs to be turned on.