Antifungal medications: Oral candidiasis, or thrush, is an oral infection where a fungus species (Candida) takes over the normal flora and causes redness and a whitish coating in the mouth. This can occur when patients are on antibiotics, steroids (dexamethasone, prednisone) or have received chemotherapy. Most patients with oral candidiasis respond promptly to treatment with Fluconazole (Diflucan) or a Nystatin solution which they swish and swallow. Because it is sometimes difficult to tell whether or not a patient has thrush, erring on the side of treating may help patients.