If you are depressed about your sexual life is not such as you want. Don’t upset, today there are o lot of methods to improve your sexual life. And most popular are drugs which are used for achieving and maintaining an erection. They work effectively almost 9 years on market and almost all people are satisfied by its effect. Only three kind of oral drugs were approved by the FDA for impotence treatment: Cialis, Levitra, and Viagra. All they increase the flow of blood into the penis. So when a man is sexually stimulated, he can get an erection. Cialis, Levitra, and Viagra have the similar mechanism for causing erection. There are subtle differences in how long the drug works and how quickly it works. works a little less than levitra. They both take effect in about 30 minutes. Levitra, has effect during 5 hours and viagra effect last approximately 4 hours. Cialis works a bit faster (within about 15 minutes), and the effects last much longer - up to 36 hours in some cases.