The FDA has also approved tadalafil for treatment of both benign prostatic hypertrophy and erectile dysfunction where the two conditions co-exist. Take tadalafil at around the same time every day. Cialis is a brand-name prescription medication. Tadalafil may cause side effects. If we combine this information with your protected health information, we will treat all of that information as protected health information and will only use or disclose that information as set forth in our notice of privacy practices. Tadalafil belongs to a group of medicines called phosphodiesterase 5 PDE5 inhibitors.generic Cialis (tadalafil) brand-name Viagra; brand-name Cialis; Sildenafil is available through Roman by prescription in , , mg pills and ranging in price from $4–$10 per dose. Brand. How Cialis Works. Tadalafil and other PDE5 inhibitors primarily work by inducing muscle relaxation. Tadalafil stops the breakdown of a chemical responsible for relaxing muscles. In ED and PAH, the drug targets muscle cells in blood vessels. When the blood vessel muscle cells relax, this expands the vessel and increases blood flow; this . Tadalafil is used to treat male sexual function problems (impotence or erectile dysfunction-ED). In combination with sexual stimulation, tadalafil works by increasing blood flow to the penis to.