Oral thrush in adults is not contagious, according to MedicineNet. However, babies who have thrush can potentially pass it to their mothers while breast-feeding, warns WebMD.
Symptoms of oral thrush include white, raised lesions on the tongue or inner cheek that often resemble cottage cheese, explains WebMD. The lesions can be painful and often bleed when they are touched.
Thrush occurs when there is an overgrowth of the fungus candida in the body, according to WebMD. It is more likely to occur in patients with uncontrolled diabetes, cancer, HIV or dry mouth. Birth control pills, antibiotics and corticosteroids can also cause thrush by affecting the balance of micro-organisms in a person's mouth.