Viagra is a prescription medicine that contains the active ingredient sildenafil. The tablets are blue diamond-shaped. Viagra is indicated for all the men who can not get or maintain an erection sufficient to complete sexual intercourse, however, that you get an erection it is necessary that there is sexual stimulation. Taking advantage of the active ingredient sildenafil, this drug can have erections stable for 4/5 hours after administration. Thanks to this treatment it is therefore possible to improve their sexual activity solving the problem of impotence.