What does it mean when your tongue gets a yellow film?

Enlarged papillae?: Usually yellow tongue is caused by enlarged tiny projections on the surface of your tongue which are inhabited by bacteria which produce yellow pigments. It is a harmless condition. If however the whites of your eyes are yellow as well you may have jaundice and should see your physician as soon as you are able. If you are unsure, it is always better to have a clinical examination.

Tongue coatings: While tongue coatings of various colors are quite common and most are the result of poor oral hygiene, medications and smoking, others require treatment. The only way to know exactly what you have and whether or not it requires any treatment is to have it looked at by your dentist.