The active ingredient in vidalista is Tadalafil. This works similarly to Sildenafil, the active ingredient in Viagra, by relaxing the blood vessels and therefore increasing the amount of blood flow in the genitals. Tadalafil 20 mg works for a lot longer, working up to 36 hours. So allows for more inspiration and does not need to be taken as often. This long work has given Tadalafil the nickname “The Weekender”.