But sometimes, the warning is louder. Oral thrush, caused by Candida overgrowth, creates thick, cottage cheese-like patches that may bleed when scraped and often signal weakened immunity, diabetes, or heavy antibiotic or steroid use. More rarely, firm white plaques that won’t scrape off can be leukoplakia, occasionally precancerous and strongly linked to tobacco. Any white coating that persists, hurts, or changes demands more than a new mouthwash—it deserves a professional exam, and your full attention.
