According to MedlinePlus, nystatin is available only with a doctor's prescription. The medication is helpful for treating fungal infections of the skin, mouth, vagina and intestinal tract.
MedlinePlus explains that nystatin comes as capsules, tablets, lozenges, powder, ointment, cream or liquid. The specific form prescribed depends upon the location of the infection. For instance, nystatin liquid treats mouth or intestinal infections. Cream or ointment is rubbed onto the skin. Powder fights a foot infection and is sprinkled onto the feet and into shoes and socks.
Itching, burning and irritation are common mild side effects of nystatin, MedlinePlus indicates. More serious side effects that require immediate medical intervention include diarrhea, nausea, stomach pain and skin rashes.