The mechanism of action for ED pills is simple: They inhibit the PDE5 enzyme which regulates the signals responsible for the smooth muscle tissue. Erectile dysfunction medications require a prescription from a licensed provider. It depends on the platform and insurance provider. Other warning signs of an unsafe online pharmacy include outdated medication, no customer service, or suspiciously low prices. While each PDE5 inhibitor differs slightly, they’re very similar in treating erectile dysfunction. Levitra vardenafil : This medication is taken one hour before sex and can last up to 24 hours. ED medications can cause side effects, and it’s crucial to have access to a medical provider if needed.Compare prices and print coupons for Viagra (Sildenafil) and other drugs at CVS, Walgreens, and other pharmacies. Prices start at $ Cart. Transfer your prescription for Sildenafil (Generic for Viagra, Oral Tablet) on Amazon Pharmacy. FREE SHIPPING for Prime members. Compare prices and print coupons for Sildenafil (Generic Revatio and Viagra) and other drugs at CVS, Walgreens, and other pharmacies. Prices start at $ Welcome!