Taking generic ED medications is an effective way to save money without sacrificing quality. The effectiveness of Sildenafil has been reviewed in clinical studies. By stopping this enzyme, the drug allows better blood flow into the penis, meaning better erections. Viagra is the most recognizable and well-known ED tablet. It changes depending on the dose.Buy Viagra Online. Bye ED. For ED, Viagra is the first port of call. It’s been used by millions of men for over 20 years, and works by boosting circulation to the penis. We’re here to . The one you’ve heard of. Works in minutes and lasts for up to 5 hours. Starting from $ Prices starting at $ Form Tablet. Available doses 25mg, 50mg, mg. . The four main medicines taken by mouth for erectile dysfunction are: Avanafil (Stendra). Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 .