Taking the medicines discussed above at the same time regarding tadalafil may create an unexpected decrease in blood pressure and, sometimes, be deadly. Here is a listing of the most popularly suggested medications that have been stated to create interactions with Tadalafil: alpha blockers, lovastatin, phenobarbital, fluoxetine, delavirdine, impotence medications, dexamethasone, HIV protease preventions, fluvoxamine, clarithromycin, medications for high blood stress, antifungals, cyclosporine, rifabutin, diltiazem, verapamil, sertraline, rifampin, isoniazid, metronidazole, phenytoin, cimetidine, erythromycin, efavirenz, and danazol.