All PDE5 inhibitors, including Viagra and Cialis, require a valid prescription regardless of the pharmacy or provider. We considered cost, medications available, and whether generic versions were offered to help reduce costs. Finally, we checked customer reviews to better understand user experiences with each platform. If you do, you may save money with online pharmacies that accept yours. Cialis tadalafil : This ED medication works with the same principle as Viagra, but lasts up to 36 hours. Other warning signs of an unsafe online pharmacy include outdated medication, no customer service, or suspiciously low prices.Viagra Coupons, Prices, and Savings Card. Generic Names: Sildenafil Citrate. Brand Names: Revatio. Sildenafil is used to treat male sexual function problems (impotence or . CVS – Online Drugstore, Pharmacy, Prescriptions & Health Information. Refill and transfer prescriptions online or find a CVS Pharmacy near you. Shop online, see ExtraCare . Our 12 Picks for Online Pharmacies of For Hair Loss: Ro. For Erectile Dysfunction: Hims. For Automatic Refills: Blink Health. For Customer Service: Honeybee .