CIALIS as needed is a treatment for adult men with erectile dysfunction. CIALIS has been shown to significantly improve the ability of obtaining a hard erect penis suitable for sexual activity. CIALIS contains the active substance tadalafil which belongs to a group of medicines called phosphodiesterase type 5 inhibitors. Following sexual stimulation CIALIS works by helping the blood vessels in your penis to relax, allowing the flow of blood into your penis. The result of this is improved erectile function.  It is important to note that CIALIS does not work if there is no sexual stimulation. CIALIS as needed is for ocassional use 30-60 minutes before sexual activity. For regular use we also have CIALIS ONCE DAILY.