In some cases, online ED providers accept health insurance. We know things can change. Cialis tadalafil : This ED medication works with the same principle as Viagra, but lasts up to 36 hours. How effective is Viagra? We also looked at additional services, such as access to digital pharmacies and home delivery options.Compare prices and print coupons for Sildenafil (Generic Revatio and Viagra) and other drugs at CVS, Walgreens, and other pharmacies. Prices start at $ Get a Savings Card Sign up for a Savings Card and, if eligible, you may save 50% on up to 12 prescriptions of brand-name VIAGRA per year.* * Terms and conditions apply. Check . a light-headed feeling, like you might pass out. Common sildenafil side effects may include: flushing (warmth, redness, or tingly feeling); headache, dizziness; heartburn, nausea, or .