Oral ED medicines might not work or might be dangerous if you also take any of the following: Nitrate medicines. It works for up to 36 hours. They include dutasteride Avodart, Jalyn and finasteride Propecia, Proscar. The products discussed in this site may have different product labeling in different countries. In some patients, the use of VIAGRA with alpha-blockers can lead to a drop in blood pressure or to fainting medicines called HIV protease inhibitors, such as ritonavir Norvir , indinavir sulfate Crixivan , saquinavir Fortovase or Invirase , or atazanavir sulfate Reyataz some types of oral antifungal medicines, such as ketoconazole Nizoral and itraconazole Sporanox some types of antibiotics, such as clarithromycin Biaxin , telithromycin Ketek , or erythromycin other medicines that treat high blood pressure other medicines or treatments for ED VIAGRA contains sildenafil, which is the same medicine found in another drug called REVATIO. These medicines all work well for ED.By Mayo Clinic Staff Medicines that you take by mouth are called oral medicines. They’re often the first line of treatment for trouble getting or keeping an . AdFree & Private Online Consultant with Real Doctors. Reliable E.D. Meds Shipped Discreetly. Save Time & Money and Get Your ED Meds Prescription & Refills Online. Discreet Packaging. AdBrowse & discover thousands of brands. Read customer reviews & find best sellers. Free shipping on qualified orders. Free, easy returns on millions of has been visited by 1M+ users in the past monthPopular Links: Pharmacy · Accessibility · Media.