What are the causes of a white-coated tongue?

Causes of a white tongue include poor oral hygiene, alcohol use, dehydration and dry mouth, according to Mayo Clinic. Other causes of a white tongue include medication use, oral thrush, oral lichen planus and some cancers.

A white tongue is a result of the swelling and overgrowth of the papillae, or finger-like projections on the surface of the tongue, explains Mayo Clinic. This coating usually develops when bacteria, debris or dead cells become stuck between the swollen papillae. In some cases, a white tongue may appear as patches instead of a coating. In this case, the cause is usually a condition such as an oral yeast infection, syphilis, leukoplakia, AIDS or geographic tongue.

In most cases, a white tongue is a harmless condition that goes away after gently brushing the tongue or using a tongue scraper, states Mayo Clinic. It is also important to drink plenty of water. Though the condition is usually harmless, a person should make an appointment with a dentist or doctor if experiencing a white tongue with pain or if the white tongue lasts longer than a few weeks. People who worry about the changes on the tongue should also make an appointment to see the doctor.