Tadalafil may cause side effects. This increased blood flow can cause an erection. Tadalafil is in a class of medications called phosphodiesterase PDE inhibitors. Do not take a double dose or more than one dose per day to make up for a missed one. If you are taking tadalafil for erectile dysfunction, your doctor will probably start you on an average dose of tadalafil and increase or decrease your dose depending on your response to the medication. Follow your doctor’s directions carefully, and ask your doctor or pharmacist to explain any part you do not understand. · Description and Brand Names. Drug information provided by: Merative, Micromedex® US Brand Name. Adcirca; 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. Tadalafil oral tablet is available as a generic drug and as brand-name drugs. Brand names: Cialis, Adcirca. Tadalafil comes only as a tablet you take by mouth. Tadalafil is used to treat the. Tadalafil is the generic name for the brand-name drug Cialis. At the time of publishing, the average cash price of 30, milligram (mg) Cialis tablets is approximately $2,, whereas.