Infectious Diseases

Oral Thrush

About Oral Thrush

Oral thrush is a very common infection in infants that causes irritation in and around a baby's mouth. It is caused by the overgrowth of a yeast (a type of fungus) called Candida albicans.

Most people (including infants) naturally have Candida in their mouths and digestive tracts, which is considered normal growth. The amount of this fungus in the body is controlled by a healthy immune system and some "good" bacteria.

If the immune system is weakened (due to an illness or medicines like chemotherapy), or if the immune system is not fully developed as is the case in infants, the Candida in the digestive tract can overgrow and lead to an infection. Candida overgrowth also causes diaper rash and vaginal (yeast) infections.

Candida overgrowth (or candidiasis) can happen after a baby has received antibiotics for a bacterial infection because antibiotics can kill off the "good" bacteria that keep the Candida from growing. Similarly, it can happen after the use of steroid medicines.


Oral thrush can affect anyone, although it's most common in babies younger than 6 months of age and in older adults.

A baby with oral thrush might develop cracked skin in the corners of the mouth or whitish patches on the lips, tongue, or inside the cheeks that look a little like cottage cheese but can't be wiped away. Scraping the white patches off can cause some bleeding.

Many babies don't feel anything at all, but some may be uncomfortable when sucking. Some babies may not feed well because their mouth feels sore.

Babies can have oral thrush and a diaper rash due to the same yeast at the same time.


Even though oral thrush is a common infection in infancy, you can help prevent it: If you are formula-feeding your baby or using a pacifier, it's important to thoroughly clean the nipples and pacifiers in hot water or dishwasher after each use. That way, if there's yeast on the bottle nipple or pacifier, your baby doesn't continue to get re-infected. Storing milk and prepared bottles in the refrigerator prevents yeast from growing.

If you are breastfeeding and your nipples are red and sore, there's a chance you may have a yeast infection on your nipples, and that you and the baby are passing it back and forth. If so, you may want to talk to the doctor about using an antifungal ointment on your nipples while the baby is being treated with the antifungal solution.

Changing diapers often also prevents fungal diaper rashes.


See your doctor if you think your baby may have thrush. Some cases go away without medical treatment within a week or two, but the doctor may prescribe an antifungal solution for your baby's mouth. This medicine is usually applied several times a day by "painting" it on the inside of the mouth and tongue with a sponge applicator.

And depending on your baby's age, the doctor might suggest adding yogurt with lactobacilli to your child's diet. The lactobacilli are the "good" bacteria that can help eliminate the yeast in your child's mouth.

If your baby keeps getting oral thrush, especially if he or she is older than 9 months of age, talk with your doctor because this might be a sign of another health issue.

Reviewed by: Yamini Durani, MD
Date reviewed: January 2015

Kids Health

