What Causes a White Coating on the Tongue?

If your tongue is discolored or coated, it's a sign that something's not quite right. A white coating on the tongue, for instance, could be a consequence of dehydration or poor dental hygiene, or a sign of a yeast infection or another mouth condition. So if you develop a white coating on your tongue, see your doctor to determine the cause and best course of action.

White substances on your tongue may be a sign of an underlying problem. (Image: Art-Of-Photo/iStock/GettyImages)


Not drinking enough fluids, taking medications that cause dehydration, drinking too much alcohol or breathing primarily through the mouth are all potential causes of dry mouth -- and a white tongue. Mouth dryness causes dead cells and bacteria to become trapped between the small bumps on the tongue's surface, causing a white appearance. To counter this problem, drink plenty of water, drink alcohol only in moderation, and talk to your doctor if you suspect a medication or breathing problem is causing your dry mouth.

Poor Oral Hygiene

When the mouth is not kept clean, debris can build up on the tongue and cause a white, coated appearance. Smoking can also cause the tongue becomes irritated and white. Prevent this with diligent oral care. Brush your teeth regularly, taking care to clean the whole mouth. Also try brushing the tongue gently with a tongue scraper -- as long as this doesn't lead to more pain or bleeding. Avoiding tobacco products is also important for many readings, oral health.


A white film on the tongue can also be a sign of thrush, an overgrowth of naturally occurring fungus -- or yeast. Although there are many types of fungi that are found in the mouth, the most common cause of oral thrush is Candida albicans. Yeast infections in the mouth can also lead to irritation, itching and redness and bleeding under the white patches. Thrush is more likely in infants, people with weak immune systems or in people who have recently taken antibiotics, as these medications can kill the good bacteria that help to regulate the growth of fungi in the mouth. Mild cases of thrush can resolve on their own, but antifungal medications may be needed to correct this imbalance.

Oral Leukoplakia

Oral leukoplakia is a white patch in the mouth that may affect the tongue or other areas. The patch can be small or may involve large areas on the tongue. Unlike the white coating caused by thrush, leukoplakia patches cannot be rubbed off. Chronic irritation of the mouth by poor fitting dentures, chewing on the inside of the mouth, or smokeless tobacco increase the risk of this condition. Some forms of leukoplakia are caused by a virus and tend to occur in people with weakened immune systems. This condition usually requires treatment, and infrequently these patches may transform into cancer -- so it is important to have persistent white patches evaluated by a doctor.

Lichen Planus

Lichen planus is a disease that can affect the skin, mouth or tongue. When it affects the tongue, it can appear as patterns of lacy, white patches or shallow ulcers. The cause is not clear but genetics, autoimmunity, medication side effects and sensitivity to oral hygiene products or metallic fillings may be connected to the onset of this condition. The underlying cause needs to be identified in order resolve or treat this disease. Treatment may involve antifungal medications, if a yeast infection is also present, or topical steroids.


If you have a white coating on your tongue, and improving hydration and oral hygiene do not resolve your symptoms, see your doctor for an assessment. A medical evaluation is particularly important if you have pain and discomfort, open sores or bleeding in the mouth, or if you have a white coating or patches on the tongue that do not clear up within 2 weeks.

Reviewed by Kay Peck, MPH RD

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