A white coating on a newborn’s tongue is a common sight that can cause concern for new parents. The discoloration is often temporary and benign, resulting from normal feeding, but it can also signal an oral infection. Identifying the difference between these two primary causes—milk residue or oral thrush—is important for determining if medical attention is needed. Observing the specific characteristics of the coating helps distinguish a simple cleanup from a treatable medical condition.
The Most Common Cause: Milk Residue
Milk residue, sometimes called “milk tongue,” is the most frequent reason a newborn’s tongue appears white, especially after a feeding. This harmless coating forms because the baby’s diet consists exclusively of milk, which leaves a residue on the tongue’s surface. Newborns also produce less saliva than adults, meaning there is less natural fluid to wash away the thin film of milk or formula.
Milk residue appears as a thin, uniform white layer, typically limited to the top of the tongue. It rarely extends to the gums, the sides of the mouth, or the palate. The most effective way to differentiate this benign residue from a fungal infection is to perform the “wipe test.”
The wipe test involves gently rubbing the white coating with a clean, soft, damp cloth or a piece of gauze. If the white film easily wipes away, revealing a healthy pink tongue underneath, the discoloration is milk residue. This residue does not require medical intervention and usually disappears as the baby begins to produce more saliva, often around four to six months of age.
Identifying Oral Thrush
Oral thrush, or oral candidiasis, presents as a more persistent white coating caused by an overgrowth of the yeast Candida albicans. This fungus is naturally present in the mouth and gut, but an immature immune system in a newborn allows the yeast population to proliferate. The infection is most common in infants under six months old.
Unlike milk residue, oral thrush appears as thicker, raised, creamy-white patches that often resemble cottage cheese. These patches are not confined to the tongue; they can be found on the inner cheeks, gums, lips, and the roof of the mouth. A key distinguishing factor is that the patches of thrush will not wipe away easily.
If a parent attempts to wipe away the patches, they typically remain stubbornly adhered to the oral tissue. Forcing removal may cause slight bleeding or reveal raw, red areas underneath, indicating an active infection. Transmission often occurs during birth if the mother has a vaginal yeast infection, or it can spread through contaminated objects like bottle nipples or pacifiers.
The yeast thrives in warm, moist environments, making the newborn’s mouth an ideal location for overgrowth. Babies who have recently taken antibiotics are at a higher risk because the medication can inadvertently kill off beneficial bacteria that normally keep Candida in check. In some cases, the infection can spread to the diaper area, causing a distinct, bright red diaper rash.
When to Take Action and Contact a Pediatrician
Parents should contact a pediatrician if the white patches do not wipe away easily or if they extend beyond the tongue to other areas of the mouth. Although thrush is generally mild, a doctor’s diagnosis is necessary to confirm the infection and prevent further discomfort. Signs that the infection is bothersome include increased fussiness during feeding or a refusal to feed due to mouth soreness.
If a baby is diagnosed with oral thrush, the typical treatment is a prescription antifungal liquid medication, such as Nystatin oral suspension. This medicine is administered multiple times a day, often four times daily, and applied directly to the affected areas. It is advised to apply the medication after a feeding, as milk can deactivate the drug’s effectiveness.
For breastfeeding mothers, medical consultation is necessary, as the infection can pass between the baby’s mouth and the mother’s nipples. Symptoms may include deep-pink, sore, or cracked nipples, or a stabbing pain deep within the breast during or after nursing. The physician may prescribe an antifungal cream for the mother’s nipples or an oral antifungal to ensure both parties are treated simultaneously and prevent reinfection.
Basic hygiene practices are important in managing and preventing the spread of the infection. This includes thoroughly cleaning or sterilizing any items that enter the baby’s mouth, such as pacifiers, bottle nipples, and breast pump parts, with hot water or a dishwasher. A pediatrician will advise continuing the antifungal treatment for a full course, even if the patches clear up quickly, to ensure the yeast is completely eradicated.