Thrush is a common yeast infection caused by an overgrowth of Candida, usually Candida albicans. It most often affects the mouth and throat, where it appears as white, creamy patches on the tongue, inner cheeks, or roof of the mouth that may be painful or bleed when scraped. Thrush can also cause redness, soreness, a cotton-like feeling in the mouth, or difficulty swallowing.

It is more common in infants, older adults, people with weakened immune systems, or those using antibiotics, inhaled steroids, or dentures. While usually mild, it can spread or become persistent in people with immune compromise. Treatment typically involves antifungal medications (like nystatin, fluconazole, or clotrimazole) and addressing underlying risk factors.