Nystatin is the prescription anti-fungal mouthwash used for thrush, according to MedlinePlus. Before each use, the liquid nystatin is shaken to ensure thorough mixing. Patients swish it around in their mouths and swallow it three to five times daily.
Thrush is caused by the Candida fungus, states MedlinePlus. It typically affects the tongue and mouth lining. Although a bit of this fungus is commonly found in the human mouth, the body's immune system and helpful bacteria usually prevent the growth of thrush. If the immune system is weak or the level of bacteria decreases, thrush spreads. This is often seen in babies; people with HIV, AIDS or diabetes; and patients on chemotherapy, steroids or antibiotics.