How oral medicines differ Each oral medicine for ED has a slightly different chemical makeup. You’ll also need to fill out a medical questionnaire with answers about your medical history, current medications, and lifestyle habits. While each PDE5 inhibitor differs slightly, they’re very similar in treating erectile dysfunction. 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. However, all medications come with risks. Both options require valid medical documentation, but some online services only require a health questionnaire to be filled out and reviewed for approval—meaning no face-to-face video interaction is needed.CHOOSE BRAND-NAME VIAGRA. The original little blue pill prescribed by doctors for over 20 years. Clinically proven to treat men with erectile dysfunction (ED) Ongoing . Amazon Pharmacy: Sildenafil (Generic for Viagra, Oral Tablet).us. Account Returns& Orders. Cart. Transfer your prescription for Sildenafil (Generic for Viagra, Oral . Compare prices and print coupons for Sildenafil (Generic Revatio and Viagra) and other drugs at CVS, Walgreens, and other pharmacies. Prices start at $ Welcome!