A white tongue and dryness of the mouth may be indications of conditions such as dehydration or oral thrush according to MedicineNet.com. Smoking, certain medications, and illnesses during which patients don't speak or eat for long periods also cause these symptoms.
A white tongue caused by dehydration occurs when people do not take in enough water to replace what their bodies have lost, notes MedicineNet.com. Vomiting, excessive sweating, frequent urination due to diabetes or urinary tract infections, burns, and the inability to drink fluids due to intense nausea can lead to dehydration. In addition to a white tongue, people suffering from dehydration may experience dryness of the mouth, dizziness, confusion and muscle cramps.
Oral thrush, or candidiasis, is a condition in which the tongue or other parts of the mouth become covered with a fungus called Candida albicans, according to Mayo Clinic. Oral thrush presents as creamy white lesions, and occurs most frequently in people with suppressed immune systems, children and the elderly. Other symptoms of oral thrush include dryness of the mouth and loss of taste. The condition is normally treated with home remedies or antifungal medications. Oral thrush prevention includes rinsing after taking medications, frequent brushing and flossing, and limiting foods containing yeast and sugar.