You will certainly have to tell your medical professional if you are going to start taking efavirenz, rifampin, medications for hypertension, alpha blockers, seizure medicines, rifabutin, bosentan, erythromycin, various other erectile dysfunction meds, amlodipine, certain antifungals, cimetidine, nevirapine, anticoagulants, HIV protease inhibitors, 'beta' blockers, or barbiturates, as a few of those medicines have been mentioned to trigger communications with Viagra.