Did you know that the tongue can be an indicator of health? Like a warning light in your car, a change in this organ’s color, from bright pink to white “scum,” can signal both minor and serious medical problems.

The white color appears when the tiny bumps on the tongue, known as papillae, become inflamed. The resulting inflammation produces a milky substance that can engulf the tongue. Three of the most common causes for tongue “scum” include:

Oral Thrush. Known also as oral candidiasis, thrush appears when the fungus Candida albicans begins to grow uncontrolled in the mouth. Oral thrush may pop up after overusing mouthwash or taking certain medications, including antibiotics. This non-life-threatening condition can also pop up among people who wear dentures or who may have a suppressed immune system. Thrush is easily treatable with the use antifungal medications that come in tablets and lozenges.

Halitosis. This condition is simply bad breath that has resulted from an overgrowth of bacteria throughout the mouth and on the tongue. The mouth is warm and wet, making it the perfect place for bacteria to flourish. Seeing a dentist, brushing twice daily, cleaning between the teeth, and eating a healthy diet rich in probiotics can help combat halitosis. Medications or bacteria-fighting mouthwashes may be prescribed.

Dry Mouth. When our salivary glands fail to produce sufficient amounts of saliva, xerostomia, or “dry mouth” can result. While this condition’s most obvious symptom is feeling parched, it can also result in a white-colored tongue. According to the Mayo Clinic, dry mouth can be caused by some cancers, medications, and aging.

While a white-colored tongue is typically harmless, it’s best to speak to your doctor or dentist since it may be symptomatic of oral cancers or other serious conditions. It’s also a good idea to consult with a medical professional if your tongue develops a reddish color since this is usually due to a lack of iron or B-complex vitamins in the diet.