|Short description Overview and Benefits   Viagra (sildenafil) is probably the common and widely used erectile dysfunction drug in the world. It is used to treat male impotence. Viagra works by relaxing the muscles and increasing the blood flow to certain areas of the body. The drug will help you achieve and retain a sturdy erection after sexual stimulation.   Viagra should not be used together with other sildenafil based drugs unless you are instructed to by your doctor. This drug should also not be used by persons under the age of 18.