Tadalafil works in a very similar way as other erectile dysfunction medications. When you get an erection, the blood within your penis increases, which makes it harden. In men who have erection problems, the blood within the penis is usually reduced.Tadalafil acts on your blood vessels and widens them. As a result, the blood flow to the penis is improved and you will find it easier to get an erection. Unlike Viagra, Spedra and Levitra, the effect of Tadalafil does not only last for four hours but 36 hours.