Thrush is caused by an infection of Candida albicans, forming white plaques on the surface of oral mucosa. Typically, it presents as small dots or patches on the oral mucous membranes that resemble curdled milk and can gradually merge into larger patches. They are not easily wiped off, without surrounding inflammatory response. Forceful removal might result in local mucosal redness, roughness, and possible bleeding. Generally, it is painless, does not cause drooling, and does not affect feeding. In severe cases of thrush, the white mucosal coating can extend to the pharynx, esophagus, trachea, and lungs, leading to symptoms like refusal to eat, low-grade fever, difficulty in breathing, and even life-threatening conditions. Typical thrush does not involve significant pain.