Levitra is the result of the combined effort of Bayer and GlaxoSmithKline to be able to provide an effective erectile dysfunction treatment. Like Cialis and Viagra, Levitra works in the same way by blocking the enzyme called phosphodiesterase-5 or PDE5. By blocking this enzyme the muscles in the penis can relax which allows for more blood flow and with the proper sexual stimulation can lead to an erection. The great thing about Levitra is that there have been reports that Levitra can work in as little as 12 minutes and stay in a person's system for up to 24 hours. The manufacturers believe this will lead to more spontaneous and thus more enjoyable encounters for people requiring this type of treatment.