Nystatin USP ointment is used to treat fungal infections on the surface of the skin caused by Candida, such as diaper rash, according to eMedtv. The medication also comes in the form of creams and powders that treat fungal infections on the skin; oral medications that treat fungal infections of the mouth and digestive tract; and vaginal tablets that treat vaginal yeast infections.
Because Nystatin is not absorbed well in the bloodstream, eMedtv advises that it is not an effective remedy for fungal infections of the bladder, brain or bloodstream. It is approved for use in children and is often used to treat thrush and diaper rash in infants.
According to eMedtv, Nystatin USP ointment and other forms of Nystatin are well tolerated, causing unwanted side effects in less than 0.1 percent of those who use it. Side effects of the ointment include eczema, itching, burning, rash and pain that occurs upon application. Oral forms of Nystatin sometimes cause gastrointestinal issues, such as nausea, vomiting and diarrhea, while vaginal tablets may cause irritation. These side effects may be annoying, but they usually are not serious. Skin peeling, severe or bloody diarrhea and rapid heartbeat are rare side effects that should be discussed with a doctor. Signs of allergic reaction, such as hives; swelling of the lips, mouth or throat; itching; rash; and difficulty breathing, require medical attention.