A generic ED trial pack allows you to try out some of the most effective ED medications and see how you react to them. It's a mix of Viagra, Cialis, Levitra, Tadacip, and other medications. There are ED medications that are really effective. Sildenafil is a drug that is used to treat difficulties with male sexual function impotence or erectile dysfunction. When used in conjunction with sexual stimulation, sildenafil helps a man get and maintain an erection by boosting blood flow to the penis. Take this medication by mouth as advised by your doctor to treat erectile dysfunction. Take sildenafil at least 30 minutes before sexual activity, but not more than 4 hours (1 hour before is the most effective). Don't take any more.