c

Sildenafil

Lasts for up to 4 hours.
Taken about 60 minutes before sexual activity.
Onset of activity may be delayed with food.
Sexual stimulation required.

c

Tadalafil

Last for up to 36 hours.
Taken at least 30 minutes before sexual activity.
Can be taken with or without food.
Sexual stimulation required.

c

Vardenafil

Lasts for up to 5 hours.
Taken about 25 – 60 minutes before sexual activity.
Onset of activity may be delayed with a high fat meal.
Sexual stimulation required.