I have a grey/white tongue.  I have been on antibiotics for about a month, most recent flagyl for the effects of the other antibiotics!  Is this the cause?  Is it dangerous?  Should I do anything?  I am 65 years old, 150 lbs. History of bladder cancer.
A gray/white coated tongue is quite normal after prolonged antibiotics. It is due to loss of the normal tongue covering. It has nothing to do with Flagyl or your cancer. Just take a multivitamin and plenty of water.