Both Cialis and Viagra work quickly. That’s not to say there aren’t just as many illegitimate sites. If approved, the provider will issue a prescription. The as-needed dose is usually 10 mg but can range from 5—20 mg. Both Cialis and Viagra work in this way. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.The price you’ll pay for sildenafil may vary based on the strength and form of the drug your doctor prescribes for you. The price may also depend on which condition is being . FAQs What to consider Cost Overdose Ask your doctor Q&A Drug Images What is Viagra? If you have erectile dysfunction (ED), your doctor may recommend that you take Viagra. . 2 days ago · Cost: Branded Viagra starts at $80 per dose and can be purchased in a day or day supply. Sildenafil is also available through the Optum Store for $6 per dose, but a higher discount may be.