To treat thrush in the baby’s mouth, the doctor will prescribe a liquid medication called Nystatin. Follow the package directions to gently rub the medication on your baby’s tongue, cheeks and gums. This is usually done after a feeding, four times a day for two days. If you are using a breast pump, pacifier or bottle nipple, you must boil it for 20 minutes, run it through a dishwasher or use a micro-steam sanitizer each day. Note that boiling may wear down bottle nipples and pacifiers, so you may have to use new ones after one week of boiling.
Also helpful: allowing your breasts to completely dry between feedings to prevent the growth of bacteria, changing nursing pads after feedings, wearing cotton bras that don't trap moisture and washing those bras frequently in hot water (drying them in the sun may also provide extra protection). Since antibiotics can trigger a yeast infection, they should be used only when needed — and that goes for both you and baby.
Over-the-counter antifungal creams, ointments or suppositories (with miconazole or clotrimazole) are the most common ways to treat yeast infections. These can take from 1 to 7 days. Your doctor may also prescribe a single-dose pill with fluconazole (an antifungal medicine) for you to take. If you’re pregnant, it’s safe to use creams or suppositories, but not the fluconazole you take by mouth.