CIALIS for use as needed was shown to improve erectile function compared to placebo up to 36 hours following dosing. Proper Use Use tadalafil exactly as directed by your doctor. Both Cialis and Viagra are effective at these doses. Keep from freezing. To provide you with the most relevant and helpful information, and understand which information is beneficial, we may combine your email and site usage information with other information we have about you. Make sure to get an estimate of when you can expect your prescription in the mail. · Cialis; Descriptions. Tadalafil is used to treat men who have erectile dysfunction (also called sexual impotence). Tadalafil belongs to a group of medicines called phosphodiesterase 5 (PDE5) inhibitors. These medicines prevent an enzyme called phosphodiesterase type-5 from working too quickly. The penis is one of the areas where . Generic name: tadalafil [ ta-DAL-a-fil ] Brand names: Adcirca, Cialis. Drug class: Impotence agents. Medically reviewed by Sanjai Sinha, MD. Last updated on Uses. Warnings. Before taking. Tadalafil (Cialis) is used to treat erectile dysfunction (ED, impotence; inability to get or keep an erection), and the symptoms of benign prostatic hyperplasia (BPH; an enlarged .