Generic Levitra is an oral drug used to treat male impotence also referred to as erectile dysfunction (ED). Generic Levitra has the same active ingredient as brand name Levitra, and is equivalent in effect, strength, and dosage. Taken 60 minutes before intercourse Generic Levitra remains active between 4 -20 hours. The success rate of oral ED drugs is very high, above 90%. However different people require different dosages to attain optimum results.