Oral Thrush in Babies: What It Looks Like and How to Treat It

If you’ve ever looked inside your baby’s mouth (which you likely will at some point), you might’ve seen some unexpected things: gums that look darker in some spots, tiny bumps and maybe even white patches on their tongue. Your baby’s mouth is constantly developing, and most of what you’ll see is totally normal. But when white patches appear and don’t seem to go away, there’s a chance it might be oral thrush.

Here’s how to tell if your baby might have thrush and how to get the treatment they need.

What is oral thrush?

Oral thrush is a yeast infection caused by an overgrowth of Candida, a fungus that naturally lives on the skin and inside the mouth, intestines and other mucous membranes. “Candida is always present in the mouth,” says Dr. Kristina Svensson, a pediatric dentist. “It only becomes a problem when it starts growing more than usual.” 

Candida can start to multiply as a response to antibiotics or even irritation of mucous membranes (like minor cuts or too much friction), which then leads to a yeast infection. And when a yeast infection happens in the mouth, it’s classified as oral thrush.

Oral thrush is especially common in babies because their oral tissues are delicate, they feed frequently using sucking motions (which causes friction) and their immune systems are still developing.

What does oral thrush look like?

Oral thrush looks like white or light yellow patches on the tongue, inner cheeks, lips or gums. The difficulty here is that it looks really similar to milk residue, which can make diagnosis “a bit tricky,” says Dr. Chris Klunk, a board-certified neonatologist at Pediatrix Medical Group.

The key difference between oral thrush and milk residue is that milk residue can be wiped off or will go away quickly. While you shouldn’t self-diagnose oral thrush before seeing a pediatrician, you can always do a quick check first. “At home, the easiest way to tell the difference between thrush and a milky tongue is by wiping the area with a cloth,” Dr. Svensson says. “Thrush will not wipe away easily and may result in redness or bleeding.”

Other symptoms might include a generally cranky or irritable baby, especially at feeding times. Some babies might seem annoyed at anything going into their mouth, so they’ll pull away from the breast or bottle, spit out a pacifier repeatedly or feed less efficiently. At the same time, Dr. Klunk says, “some cases of thrush don’t cause any discomfort at all, and don’t have any effect on baby’s ability to eat.”

What causes oral thrush in babies?

Since babies’ mouths are so sensitive and they’re always putting things in there (bottles, fingers, toys, anything they can get their hands on), there are several things that can make thrush more likely:

• Prolonged sucking (including breastfeeding, bottle feeding and pacifiers), which can irritate the lining of the mouth

• Antibiotics, especially for breastfeeding parents, which can disrupt the natural bacteria/yeast balance

• Exposure during a vaginal birth if the parent had a yeast infection

• Cracked or irritated nipples in breastfeeding parents

• Using an inhaler, nebulizer or other oral medicine device that hasn’t been cleaned between uses

Is thrush contagious?

Thrush doesn’t spread like viral or bacterial infections—it’s not transmissible through the air or basic skin-to-skin contact—so your baby can still go to childcare as long as they’re feeding comfortably and normally.

But thrush can pass back and forth between a breastfeeding parent and baby. That’s why sometimes both of you might need treatment, even if only one of you has symptoms. Symptoms in breastfeeding parents can include burning, itching or stinging nipples, or red and cracked skin.

How is oral thrush treated?

If your pediatrician confirms oral thrush, they may prescribe an antifungal treatment (usually an oral liquid) for your baby. If you’re breastfeeding, you may receive treatment too to stop it from passing back and forth. Once treatment is started, most cases of oral thrush clear up within about a week or two.

Your pediatrician may also recommend thoroughly cleaning baby’s feeding items in order to prevent them from being reinfected, Dr. Klunk says. That typically includes cleaning or sterilizing bottle nipples, pacifiers, teethers and any toys baby likes to chew on, plus any nipple shields, breast pump flanges or reusable nursing pads you might be using.

And when it comes to general prevention, Dr. Svensson says that regular checks of baby’s mouth are key. “Getting comfortable checking your baby’s teeth, lifting their lips and looking into their mouth is a valuable part of taking care of your baby, even if they get mad about it sometimes.”

And as always, trust your instincts. If something looks unusual or your baby suddenly changes how they eat, reach out to your pediatrician.