In the days or weeks after birth, a person may notice that their newborn has a white tongue. The white coating could be milk residue or oral thrush.

It is not uncommon for a newborn to have a white tongue. Their primary source of nourishment is breast milk or formula, so milk residue from a recent feed is the most likely cause of this discoloration.

Sometimes, a newborn may have oral thrush, which is a type of yeast infection. Thrush is a common infection that is easy for a doctor to treat.

In this article, we examine the possible causes of a baby having a white tongue. We also look at symptoms and treatments.

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Having a white tongue is fairly common among newborns. More often than not, the cause is milk residue, but it could also be a symptom of oral thrush.

Newborns tend to have a buildup of milk on their tongue. As they do not produce as much saliva as older children, there is less saliva in their mouth to wash away the milk.

Some newborns develop oral thrush, which is the most common oral fungal infection in infants and children. An overgrowth of a fungus called Candida causes thrush.

Symptoms of oral thrush in newborns include:

  • white mouth sores resembling cottage cheese, which do not rub off
  • white patches inside the cheeks and on the tongue, gums, and roof of the mouth
  • white spots in the mouth
  • redness in the mouth
  • cracking in the corners of the mouth
  • fussiness during feeding
  • clicking sounds when feeding
  • diaper rash

The human body harbors various microorganisms, including bacteria, viruses, and fungi. Together, these form the human microbiota. Candida albicans is the most common fungus of the human microbiota.

Candida usually lives on the skin and inside the body in places such as the:

  • mouth
  • throat
  • gut
  • vagina

In most cases, Candida does not cause any issues, but it can sometimes multiply and cause infection if its environment alters to encourage fungal growth.

After birth, a newborn’s immune system is not yet fully functional. The dampened immune system may increase a newborn’s chances of infection and allow Candida to multiply and cause oral thrush. Yeast thrives in moist, warm areas, so the mouth is the perfect environment for a yeast infection.

Some medications, such as corticosteroids and antibiotics, may also cause oral thrush. Although antibiotics treat bacterial infections, they also kill “good” bacteria, which may allow Candida to grow.

If a person experiences a vaginal yeast infection during pregnancy, the Candida could transfer to the newborn during birth.

A doctor may prescribe antifungal medication as an oral gel to treat thrush. A person should apply the medicine to all areas of the newborn’s mouth, including the gums, cheeks, tongue, and roof of the mouth, several times a day.

Newborns can transfer the infection when breastfeeding, so a person should also apply the gel to their nipples after every feed. Even if someone is not showing signs of thrush in the nipple, areola, or breast, they should receive treatment to prevent reinfection.

Oral thrush does not usually cause complications in healthy newborns and children.

However, the infection can sometimes be severe for people with lowered immunity.

In rare cases, Candida infections can spread to other parts of the body if a person’s immune system is not functioning correctly.

At its most severe, a Candida infection may affect the blood, the membrane that lines the heart muscle, and the brain’s membranes.

People tend to confuse oral thrush and milk residue because they have a similar appearance. It can be challenging to distinguish between the two.

To tell the difference, a parent or caregiver can try gently wiping the white film off the newborn’s tongue using a warm, damp cloth. If the white coating wipes away, it is likely milk residue.

Milk residue is usually more noticeable immediately after a newborn feeds due to their relatively low saliva production. Milk residue tends to disappear within a few hours after feeding or once the baby begins to produce more saliva.

Thrush does not disappear from the tongue’s surface, even after wiping, but remains in the form of patches with a cottage cheese-like appearance. Trying to wipe away the white patches might also leave red spots that may bleed.

Parents and caregivers should take a newborn to see a doctor if they have symptoms of oral thrush. A doctor will examine the newborn’s mouth to look for white lesions and prescribe antifungal medication.

If a doctor suspects that an underlying medical condition is causing oral thrush, they may perform a physical examination and blood tests.

Steps that parents and caregivers can take to help prevent thrush from returning in their newborn include:

  • sterilizing feeding equipment, bottles, breast pumps, pacifiers, and toys
  • refrigerating pumped milk to prevent the growth of yeast
  • treating the nipples for thrush if breastfeeding
  • wiping the breast dry after every feed
  • changing nursing pads frequently

It is quite common for newborns to have a white tongue, which could be due to oral thrush or milk residue.

Although milk residue and oral thrush look similar, there are differences. Milk residue usually fades away after a feed, whereas oral thrush does not disappear, even on wiping the tongue with a damp cloth.

Oral thrush is easy to treat and may start to clear within a few days. A doctor will usually prescribe antifungal gel for the newborn and also for the person breastfeeding them.

Parents and caregivers can take steps to prevent the growth of yeast by keeping feeding equipment clean and milk refrigerated, as well as keeping the breasts dry if breastfeeding.