This is so weird. . .I too have a white coating on the back of my tongue. I never related it to my IBS, although the toxin idea seems logical. Anyway, I think this contributes to bad breath. I think the white coating is some sort of bacteria which causes the bad breath. Anyway, this is just a theory, no one write back telling me I am wrong or whatever. Also, when I use one of those tongue scrapers to remove the coating, the next day, I have blister-like sores on the back of my tongue. They hurt like hell, so I have stopped using the scraper. I just use Listerine which I also read was bad cuz in the long run, it has a lot of alcohol, and can really dry out your mouth which causes bad breath in the first place. BOOHOO< my life is just a vicious cycle of bad medical mysteries.LALAReading these posts kind of make me laugh cuz I just picture us (IBSers and Worriers) in the bathroom after an attack obsessing about out coated tongues, or weird rashes, or a different smell, or . . . . .was that an eye twitch. . . .?