Yes, after a foot injury, I ended up with 2 of the most ugly toenails in the world. There's no way in hell that a topical is going to go through the nail and get to the root and kill the fungus at the source (if you believe the commercials.)
Yes, you need a prescription for it, but...
no, that doesn't necessarily mean your insurance is going to cover it. I have quite good insurance, but mine wouldn't cover it. It's expensive, but you may be able to save a little $$ by getting it from Canada. Takes a long time for the infected nail to grow out far enough that it's gone - my treatment ended a while before the infected part of the nail was gone. But, the day I clipped off the last bit of yellow nail and nothing left but a nice nail was one of those happier occasions. It worked for me.