What is thrush?

Q: My baby boy has white patches on the insides of his cheeks. What is it?

A: Generally, when parents notice white patches on the insides of their infants’ cheeks, it’s usually a condition known as thrush.

Thrush is an excessive growth of a yeast (fungus) in the mouth and is very common among infants in the first few months of life. 

The white patches adhere to the mucous membranes on the sides of the cheeks.

Severe cases can involve the inside of the lips, and may even be uncomfortable for your child.

The surface of the tongue may also show a white coating in these cases.

The main reason why thrush can frequently happen in young infants is that their immune systems are still forming.

Infants who are on antibiotics will have a higher likelihood of developing thrush.

Also, moms who are breastfeeding and also taking antibiotics are more likely to have infants who develop thrush.

There are a number of medications that can help treat thrush, including a liquid that contains nystatin (an antifungal agent).

While thrush isn’t dangerous or disfiguring, it can be stubborn when you’re trying to get rid of it.

And it can come back easily once treatment is completed.

If you believe your child may have thrush, talk to your child’s clinician.   


Dr. Peter Dehnel is a board-certified pediatrician and medical director with Blue Cross Blue Shield of Minnesota. Send questions to drdehnel@mnparent.com. This column is intended to provide general information only and not medical advice. Contact your health care provider with questions about your child.