Is Tadalafil Stronger Than Viagra? Understand whether or not Tadalafil would be more effective in treating ED than the widely used Viagra. When patients come to us looking for relief from their erectile dysfunction, they are faced with a preliminary decision of which medication, tadalafil or sildenafil, is better. Back in the day, when these medications were still on patent AND named Cialis and Viagra, respectively, they were very costly.