Cialis is a prescription medicine taken orally for the treatment of erectile dysfunction (ED) in men. Cialis has been shown to improve erectile function compared to placebo up to 36 hours following dosing. In clinical studies, the ability to have sexual activity was improved in some patients at 30 minutes after taking a dose.

Levitra is an FDA-approved oral prescription medication for the treatment of erectile dysfunction (ED) in men. Levitra should be taken no more than once per day. Levitra helps increase blood flow to the penis and may help men with ED get and keep an erection satisfactory for sexual activity. Once a man has completed sexual activity, blood flow to his penis should decrease and his erection should go away.

Viagra (sildenafil citrate) is a breakthrough treatment for male erectile dysfunction, often called impotence. Viagra is a convenient, discreet pill you take only when you want to have sex. Viagra can help many men who have E.D. get and keep an erection when they become sexually stimulated.