Nystatin is an antifungal medication. It is used to treat certain fungus and yeast infections. It is considered the drug of choice for treatment of Candida infections. However, nystatin is not systemically absorbed in the gastrointestinal tract, and must come into direct contact with the organism to be effective.
In the United States, nystatin is one of the few drugs approved by the FDA for use in egg laying hens.