Sildenafil: the science
- When you get aroused, your body produces a molecule called cGMP which helps to stimulate an erection by increasing blood flow to the penis.
- However, an enzyme known as PDE5 normally breaks cGMP down. This restricts blood flow to the penis and causes the erection to subside.
- Sildenafil blocks the action of PDE5, allowing more blood to flow into the penis. The resulting erection is firmer and usually lasts long enough to allow for satisfying sex.