Be sure to mention any of the following: alpha blockers such as alfuzosin Uroxatral , doxazosin Cardura , dutasteride Avodart, in Jalyn , prazosin Minipress , silodosin Rapaflo , tamsulosin Flomax, in Jalyn , and terazosin; amiodarone Cordarone, Pacerone ; certain antifungals such as fluconazole Diflucan , griseofulvin Grifulvin, Gris-PEG , itraconazole Onmel, Sporanox , ketoconazole Extina, Ketozole, Nizoral, Xolegel , and voriconazole Vfend ; aprepitant Emend ; bosentan Tracleer ; carbamazepine Carbatrol, Epitol, Tegretol, Teril, others ; clarithromycin Biaxin, in Prevpac ; diltiazem Cardizem, Cartia,Tiazac, others ; efavirenz Sustiva, in Atripla ; erythromycin E. You should take tadalafil one time a day. CIALIS for Use as Needed for ED In eight primary placebo-controlled clinical studies of 12 weeks duration, mean age was 59 years range 22 to 88 and the discontinuation rate due to adverse events in patients treated with tadalafil 10 or 20 mg was 3. Follow your doctor’s directions carefully, and ask your doctor or pharmacist to explain any part you do not understand. Also, do not stop taking this medicine without checking first with your doctor. Tadalafil belongs to a group of medicines called phosphodiesterase 5 PDE5 inhibitors. This medicine can cause serious side effects in patients with heart problems.Generic name: tadalafil [ ta-DAL-a-fil ] Brand names: Adcirca, Cialis. Drug class: Impotence agents. Medically reviewed by Sanjai Sinha, MD. Last updated on . Tadalafil, or generic Cialis, is most commonly used to treat erectile dysfunction (ED). However, it’s also used to treat benign prostatic hyperplasia (BPH) and pulmonary .  · The maximum dose of Cialis that can be taken in a day is 20 mg. You should not take Cialis more than once a day. In clinical trials, Cialis helped people with ED symptoms for up to