White Tongue: What It Is and How to Treat It A white tongue occurs when a film—covering part or all of the tongue—develops, often with a bad taste or odor. It may resemble white “hairs,” which are actually enlarged buds coated with bacteria, food particles, and dead cells. Common Causes: White tongue often results from poor oral hygiene, bacterial buildup, or irritation. Sometimes, it’s linked to conditions like geographic tongue, where white patches appear due to inflammation triggered by certain foods, stress, or hormonal changes. Other causes include dry mouth, infections, smoking, or illnesses. The plaque may also be yellow (possible liver issues), brown (from excess tea or coffee), or red (vitamin B deficiency).