Try Digestive Enzymes! My white coated geographic tongue appears to be caused by digestive/gut issues. I have done a lot of research over the years and a lot of trial and error. I have tried many things. A strict gluten free, corn free, gmo free, dairy free, alcohol free diet helps tremendously but still there are days when I want to eat some of those things. I discovered digestive enzymes about a year ago and they have helped me the most!! I take 3 capsules with every meal and my tongue has been mostly pink for the past year. It is the only thing I have tried that has really cleared up my tongue. In addition, I drink a cup of senna tea every night to keep things moving in my intestines.
I suffer from slow gut motility and constipation as well. I brush with a natural toothpaste. And follow up with a dry mouth rinse that has glycerin. But all these other things - strict diet, nightly senna tea, natural toothpaste, dry mouth rinse - I have been doing for many years and they didn't completely help my white tongue. Even multi-strain expensive probiotics didn't help. Digestive Enzymes are the only thing that has helped - it has changed my life! I've even stopped the expensive probiotics. I think a good diet is also key -but I even splurge now and then...and with the digestive enzymes, my tongue has been ok. Or if I have a flare up it clears up within a day.
When Gut imbalance is the problem - Digestive Enzymes are the solution!
Hope this helps someone! Note: I have never had bad breath, so maybe there are other reasons for white tongue that the digestive enzymes won't help. But for a white coated geographic tongue, they will help!