This increased blood flow can cause an erection. Brand names Why is this medication prescribed? One of the first Cialis ads aired at the Super Bowl. Do not take a double dose or more than one dose per day to make up for a missed one. You should only be treated with one of these products at a time. You should take tadalafil one time a day. Your doctor will probably tell you not to take tadalafil if you are taking street drugs containing nitrates.Tadalafil has been on the market since and has the same primary ingredient as Cialis. While the chemical make-ups of Cialis and tadalafil may be a little . tadalafil Used for Benign Prostatic Hyperplasia, Erectile Dysfunction erectile dysfunction (ED) benign prostatic hyperplasia, or BPH). Tadalafil (Cialis) is available .  · The typical dose for once-daily Cialis for ED is milligrams (mg) to 5 mg. When used as needed for ED, the usual Cialis dose is 10 mg (with a maximum daily dose of 20 mg). The typical dose of.