A coated tongue could be an indication of liver/gallbladder or even bowel congestion. It could also be that you have disrupted the acid/alkaline balance in your mouth and allowed a bacterial or fungal infection to take root. The mouth needs to be slightly acidic to support normal acidolphilous bacteria that line the digestive system and help prevent the "bad guys" from gaining the upper hand. The skin, mouth, digestive system all need to be on the acidic side to keep the balance of good and dangerous bacteria in balance. Perhaps swishing a little diluted raw apple cider vinegar in your mouth will help restore its needed pH. The good news is the cider vinegar breaks down, or metabolizes, into an alkaline ash, so it will not affect the pH of the blood and stress the body.