What is that white or yellow stuff on my tongue? How do I avoid it?
Coatings on the tongue can come from any of a number of causes. The surface of the tongue is studded with myriad bumps known as papillae. They come in three types: filliform, fungiform, and circumvallate. The fungiform and circumvallate contribute to taste perception; they are the larger bumps on the front or the back of the tongue respectively. The most numerous type are the small filliform papillae, which cover the majority of the dorsal (upper) surface of the tongue. Sometimes the filliform papillae either hypertrophy (grow larger) or atrophy (grow smaller) as a result of chemical, endocrine, or microbiological factors. This will give rise to changes in the appearance of the tongue. For instance, the habitual use of hydrogen peroxide-containing mouthrinses will cause the filliform papillae to grow, leading to a clinical condition elegantly known as “black hairy tongue.” Strep infection will sometimes take the form of scarlet fever (scarletina), which causes the filliform papillae to