By causing the penis to vasodilate, Tadalista 20, which contains generic Viagra, another name for Sildenafil, will cause erectile dysfunction. The dilatation effect allows the blood vessels in the penile region to expand, increasing the blood pressure and making it possible to stimulate the formation of the penis. Nitric oxide, which appears in your body as a vasodilation natural agent, is where the vasodilation effects originate from.