What causes a thick and yellow tongue coating?

A thick, yellow tongue coating may be caused by various factors. Poor oral hygiene, bacterial overgrowth in the mouth, and accumulation of food debris can all lead to a thickened, yellowish tongue coating. Digestive system issues, such as excessive stomach heat or indigestion, may also manifest on the tongue, resulting in a thick, yellow appearance. Dietary habits—such as consuming excessive spicy or greasy foods—or long-term smoking can further contribute to these changes. Patients should maintain good oral hygiene by regularly brushing teeth, using dental floss, and rinsing with mouthwash to keep the mouth clean. Adjusting dietary habits by reducing intake of spicy and greasy foods and increasing consumption of light, easily digestible foods is recommended. For digestive issues, traditional Chinese medicine treatments—such as cupping therapy or taking herbal medicines with heat-clearing and detoxifying effects—may help improve the condition of the tongue coating.