You can get a prescription online following a quick and easy visit with a member of our clinical team. Privacy: Confirm that your personal data and payment details are confidential. What Are the Symptoms of Erectile Dysfunction? It’s available in 25 mg, 50 mg, and mg tablets and lasts up to 18 hours. You deserve to put ED behind you and to enjoy your sex life.Generic Viagra (sildenafil) is an alternative to the branded Viagra drug that can be used for treating erectile dysfunction (ED). It’s now sold by many manufacturers, including online. Typical dosing for Sildenafil (Viagra) The typical dose is to take 50 mg of sildenafil (Viagra) by mouth, about 1 hour before sex, as needed. The maximum recommended dose is mg. Don’t take sildenafil (Viagra) more than once daily (at any dose). Written by Brian Leonard, PharmD, BCACP, BCGP.  · Compare prices. Drug prices vary by pharmacy. Use GoodRx to find current prices and discounts. Get free coupons. GoodRx coupons can help you pay less than the cash price for your prescription. Show to your pharmacist. It’s easy. Just bring your free coupon to the pharmacy when picking up your prescription.