What is Thrush?

— What is Thrush?

Thrush or oral thrush is a common infection in infants that can cause irritation in and around a baby’s mouth. It is caused by the overgrowth of a yeast called Candida albicans, a type of fungus. Oral thrust is generally not a serious condition in itself. However, it can be uncomfortable and lead to difficulties with eating or infant feeding if it does not resolve or is not treated. It can also be experienced by toddlers, older children and adults.

Most people, about 50% of the population, naturally have Candida in their mouths and digestive tracts – this is normal. The amount of this fungus in the body is typically controlled by a healthy immune system and “good” bacteria. However, some factors or conditions may result in an overgrowth of Candida albicans.

People at risk for oral thrush include those taking strong antibiotics, especially for a long period of time. Antibiotics kill bacteria, which can alter the balance of microorganisms in the mouth and result in a proliferation of yeast.

If the immune system is weakened (like due to an illness), or if the immune system is not fully developed (like in an infant), 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, but it is most common in children younger than 6 months and in the elderly.

The first sign that an infant might be experiencing thrush is if he or she is acting unsettled, especially when feeding because her mouth is sore. However, many babies are not bothered by thrush. 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.

Thrush shows as white patches on the roof of the mouth, inside the cheeks and on the tongue. There may be redness around the patches, and they might look like ulcers. If an older child or adult gets thrush in the mouth, or ulcers that look like they may be thrush, it may be a sign of another disease, so have a doctor check. Signs of thrush can occur suddenly. Thrush can also be difficult to get rid of, especially in infants. Lesions can appear within the mouth which can be painful. Other symptoms can include a loss of taste, or feeling as if swallowed a cotton ball. The thrush can become severe enough that one may have difficulty swallowing food.

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. In an older child or toddler, a loss of appetite can be a sign.

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

If you think your child may have thrush in the mouth, one needs to go to a doctor or child health nurse to be sure, and to get advice about treatment.

Preventing Thrush

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. This helps from reinfection. Storing milk and prepared bottles in the refrigerator also prevents yeast from growing.

The treatment may be drops or a gel which needs to be spread around the inside of the mouth, not just put on the tongue. If the baby is breastfeeding, the mother’s nipples may need to be treated at the same time as the baby to prevent the infection passing back and forth.

Changing diapers often also prevents fungal diaper rashes.

Treatment of Thrush

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.