Take all of the tablets for your daily dose at one time each day; do not divide the tablets to take as separate doses. In trials investigating Cialis, the majority of participants receiving the drug experienced a significant improvement in ED and maintained an erection. 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. If you ever need emergency medical treatment for a heart problem, the health care providers who treat you will need to know when you last took tadalafil. How Effective Is Cialis? The FDA has also approved tadalafil for treatment of both benign prostatic hypertrophy and erectile dysfunction where the two conditions co-exist.Drug Facts Common Brands Cialis Drug Class PDE-5 inhibitor Controlled Substance Classification Not a controlled medication Generic Status No lower-cost Missing: knock off. Cons can cause headaches and muscle aches must be swallowed whole can cause indigestion can make you appear flushed not available over-the-counter (OTC) Missing: knock off. The most common side effects with Cialis are: headache, indigestion, back pain, muscle aches, flushing, and stuffy or runny nose. These side effects usually go away after a few hours. Men who get back pain and muscle aches usually get it 12 to 24 hours after taking Cialis. Back pain and muscle aches usually go away within 2 days.