Cialis tadalafil : This ED medication works with the same principle as Viagra, but lasts up to 36 hours. The best online pharmacies are accredited by the National Association of Boards of Pharmacy and are licensed in every state in which they trade. Sudden vision loss in one or both eyes can be a sign of a serious eye problem called non-arteritic anterior ischemic optic neuropathy NAION. This information is reviewed by a licensed practitioner who will assess your eligibility for the medication. This increase in blood flow results in a firmer, longer-lasting erection. Remember that expediting will cost extra.Vision changes. Muscle pain. But there are some differences. With Viagra, there is a higher risk of vision changes than with Cialis. Among people who take Viagra or sildenafil, 3% get blue vision that lasts a few hours. On the other hand, Cialis has a slightly higher risk of muscle pain than Viagra and vardenafil. The Savings Offer and Program expire on 12/31/ For further information, call , visit test1.ru, or write: Viatris Inc., P.O. Box , Mission, KS See risks & benefits. Learn more about what VIAGRA® (sildenafil citrate), a prescription treatment for ED. Online Pharmacy & OTC. Our 12 Picks for Online Pharmacies of If you need medication delivered here are the best online pharmacies—and how to choose the right one for you. By Natalie Rahhal. Updated on April 21, Medically reviewed by Chris Vincent, MD. Fact checked by James Lacy. Print.