How long does it take for levitra to take effect? about 30 minutes How long does it take erectile dysfunction medication to work? Viagra and Levitra take about 30 minutes to work, and the effects last for about 4 hours after you take the pill. You should take Cialis at least 2 hours before you plan to have sex. Does Levitra help you last longer? A number of prescription treatments are available for erectile dysfunction such as Viagra, as well as Cialis, Spedra, Levitra and Sildenafil. Essentially they all help you gain and maintain an erection by increasing blood flow to your penis; helping you last longer in bed.