Using alcohol or tobacco with certain medicines may also cause interactions to occur. Cialis will be available by prescription only. Urapidil Voriconazole Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If you need emergency medical care for a heart problem, it will be important for your health care provider to know when you last took Cialis. Do not use this medicine if you are also using riociguat or a nitrate medicine, often used to treat angina chest pain. For treatment of erectile dysfunction and benign prostatic hyperplasia daily use : Adults—5 milligrams mg once a day, taken at the same time each day, without regard for the timing of sexual activity. Grapefruit Juice Using this medicine with any of the following may cause an increased risk of certain side effects but may be unavoidable in some cases.Generic tadalafil has been available since and has proven to be just as effective and safe as the brand name. The drug is available in low daily doses that keep the medication in your system. Cialis (tadalafil) is a type of PDE5 inhibitor that the Food and Drug Administration approved in Like other PDE5 inhibitors, it increases blood flow to the penis. There are two different ways to take Cialis: as needed or daily.