Those who don’t feel comfortable discussing ED with an in-person provider or lack time to visit a doctor’s office may find online ED prescriptions beneficial. In some cases, online ED providers accept health insurance. ED medications can cause side effects, and it’s crucial to have access to a medical provider if needed. Find answers Answer: For most men who take Sildenafil, it works the first or second time. Insurance: If you plan to use insurance, make sure the online provider accepts it.Consumer Reports Best Buy Drugs shares how you might be able to get generic Viagra, known as sildenafil, at a much lower price. “Most patients benefit from taking a 50 to mg dose. To treat erectile dysfunction-ED, take this drug by mouth as directed by your doctor, usually as needed. Take sildenafil at least 30 minutes, but no more than 4 hours, before sexual activity (1 hour before is the most effective). Do not take more than once daily. A high-fat meal may delay how quickly the drug begins to work. Amazon Pharmacy: Sildenafil (Generic for Viagra, Oral Tablet).us. Account Returns& Orders. Cart. Transfer your prescription for Sildenafil (Generic for Viagra, Oral Tablet) on Amazon Pharmacy.