The tongue appears to have a thick, white coating due to inflammation and trapped particles, such as dead cells and bacteria. The causes of a white tongue coating are varied. Usually, white tongue poses little concern and may be caused by dehydration, mouth breathing, medications, alcohol use, smoking, or fever.
Some more serious conditions also cause the symptom, including the following: leukoplakia, which can be an early sign of cancer; syphilis, a sexually transmitted infection; trush, a yeast infection of the mouth; an autoimmune disease called oral lichen planus.
To treat this form of coated tongue, brush or scrape your tongue. Drinking extra water may help if dehydration is a cause. You can prevent white tongue through eliminating excessive alcohol consumption, quitting smoking, breathing through your nose, and practicing good oral hygiene. If the coating lasts longer than two weeks or is accompanied by other symptoms such as pain or swelling, seek medical care.