I've noticed a pretty think white layer on the very back of my tongue. I can brush it off but it usually makes me gag, within a few hours its back again. I'm not sure if i have always had this but i just realized it a couple of months ago because i have been suffering from dry mouth for a little while. Is this normal? Is having a thin white film on the back of your tongue something to be worried about? i have no sores in my mouth, it doesn't hurt to brush it off, and i never bleed when i brush it off. It just sits there at the very back of my tongue.