Viagra is a medicine that is taken to treat erectile dysfunction. Erectile dysfunction happens when you are unable to get or maintain an erection when having sex with your partner. You might have erectile dysfunction if you can't get or keep an erection for four hours, on the first date of sex or at all. Viagra has been around for decades and is one of the most popular medications in the world. It helps men with erectile dysfunction retain an erection, maintain their erections, and delay ejaculation until their partner achieves satisfaction. Viagra is a drug used to treat erectile dysfunction (ED), also known as impotence. It works by enhancing the blood flow through your penis by increasing the amount of blood flowing into it. Viagra can also be used to treat premature ejaculation.