The generic versions are just as effective and much less expensive. This is important for your overall health and safety, as certain medications can negatively interact with each other or cause existing conditions to worsen. An erection results from an increase in blood flow to the penis. 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. People with heart conditions should never take ED medications without consulting a doctor. You’ll also need to fill out a medical questionnaire with answers about your medical history, current medications, and lifestyle habits.We reviewed and compared prices, insurance coverage, and safety from the best online ED prescription companies. This list will help you find the best ed meds online to fit your needs. Branded Viagra: $90 per 25 mg, 50 mg, or mg pill; Generic Cialis (tadalafil): $11 per 5 mg pill, $44 per 10 mg or 20 mg pill;. Learn more about what VIAGRA® (sildenafil citrate), a prescription treatment for ED. This Savings Offer is limited to 50% savings off the amount of your co-pay or your out-of-pocket cost, whichever is less, with a maximum savings of $ off each prescription for up to 12 prescriptions in a calendar year. 50 mg, and mg tablets. The normal dose when starting Viagra is 50 mg, as needed. The maximum dose of Viagra is mg each day. Doses above the maximum dose, such as mg per day, will increase the risk of.