Will Cialis be prescription or OTC over-the-counter? If you become pregnant while taking tadalafil, call your doctor. Do not stop taking tadalafil without talking to your doctor. Tell your doctor if tadalafil is not working well or if you are experiencing side effects. Tadalafil treats PAH by relaxing the blood vessels in the lungs to allow blood to flow more easily.Tadalafil is a medicine used to treat erectile dysfunction (ED, also called impotence) and problems with urination caused by an enlarged prostate (benign prostatic hypertrophy or BPH). It is sometimes known by its generic name tadalafil, and sometimes known by its trade name, Cialis. There are also other brands of this medicine available. Cialis and generic Cialis, known as tadalafil, are available from online services, along with other ED treatment options for people looking to buy ED medication online. Tadalafil, the generic version of Cialis is available for about $9 for 30 tablets of the 5 mg strength. Does cialis have a generic? expand_more. Yes, Cialis is available as a generic medication called tadalafil. Generic medications are just as effective as the brand. Tadalafil 10 mg is available for about $10 for 10 tablets with GoodRx.