I had taken terbinafine for about six weeks for a toenail infection when my sense of taste pretty much completely disappeared over the course of 3-4 days. I have a vague salty/bitter taste in my mouth, but nothing tastes of anything....sweet, salt, bitter...all gone. I can put pure sugar on my tongue and not taste a thing. That refreshing zing you get from toothpaste? Gone. Everything tastes grey at best, or just nasty at worst.
The infection responded well to terbinafine - I have about 4mm clear nail now, but I've decided to stop taking it as nothing is worth this cost. I've switched to Loceryl lacquer but I don't even care about the nail anymore. I just desperately want to be able to taste things normally again. I can completely understand how this can cause weight loss and depression. My advice would be to avoide terbinafine.