Oral Thrush in Infants: Causes and Treatments

As a parent or caregiver, the appearance of white patches in your baby’s mouth can be worrisome, especially if the baby seems fussy or refuses to eat. These signs could indicate the presence of thrush, a common fungal infection in infants that can cause discomfort and feeding difficulties. Although the condition is not usually serious, it requires proper treatment and care to prevent it from spreading or recurring.

Understanding the causes of thrush and how to treat and prevent it can help you keep your baby’s oral health in top condition. In this article, we’ll explore thrush, its causes, symptoms, and treatment options, along with preventive tips, to help keep your baby healthy and comfortable.

What is oral thrush in infants?

Oral thrush is a common mouth infection in babies, caused by a type of fungus that lives in our bodies. This fungus is called Candida, and it’s usually harmless. It lives quietly in places like the mouth, tummy, and skin. But sometimes, it grows too much and causes an infection; this is what we call oral thrush.

In babies, oral thrush often shows up as white or creamy patches on the tongue, inside the cheeks, on the gums, or lips. It might look like milk, but the difference is that you can’t wipe it off easily. If you try to clean it, it may leave red or sore spots. Some babies don’t seem bothered by it, while others may get fussy, especially when feeding.

Is thrush only a baby thing?

Not at all. While oral thrush is super common in infants, it can affect adults too – just under different circumstances. Adults are more likely to get it if they:

• have a weakened immune system due to illness or medication.
• use dentures or corticosteroid inhalers.
• are going through chemotherapy or taking long-term antibiotics.

However, in this article, we’ll focus on oral thrush in infants, since their vulnerabilities and care needs are quite specific.

Causes of oral thrush in infants

Oral thrush is very common in newborns, especially in babies under two months old. At that age, their immune systems are still developing, and they’re not yet great at fighting off infections. That’s one of the main reasons why thrush can show up early in life.

But it’s not always about the immune system alone; there are several factors that can create the perfect environment for the fungus to grow in a baby’s mouth.

• Birth canal exposure: Sometimes, a baby can get thrush while being born, especially if the mother has a vaginal yeast infection at the time of delivery. As the baby passes through the birth canal, the fungus can be passed along too. This is why some newborns develop thrush just a few days or weeks after birth.

• Immature immune system: Newborns are born with an underdeveloped immune system, which means they are not yet fully equipped to fight off infections. This makes it easier for Candida to multiply and cause an infection.

• Antibiotic use: Both babies and breastfeeding mothers who take antibiotics may be at higher risk for thrush. Antibiotics are great for fighting bacterial infections, but they can also wipe out the “good bacteria” that normally help keep fungus in check. Without those good bacteria, fungus can take over more easily.

• Unclean pacifiers, bottles, or teething toys: Pacifiers and bottle nipples spend a lot of time in a baby’s mouth. If they aren’t cleaned or sterilized properly, they can collect germs, including fungus. Since Candida loves warm, moist places, these items become a perfect hiding spot for it, and putting them in the mouth gives the fungus direct access.

• Breastfeeding transmission: Sometimes the yeast infection is transmitted back and forth between the baby’s mouth and the mother’s nipples. If a mother has thrush on her nipples, the baby may develop oral thrush. Likewise, if a baby has thrush, it can lead to nipple pain or an infection in the mother.

Risk factors: when thrush is more likely to appear

While any baby can get thrush, some are at higher risk than others, especially if their immune system is still extra sensitive or they’re dealing with other health challenges.

Thrush is more likely or may be more persistent in:

• Premature babies, whose bodies are less developed and need more protection.
• Babies with very low birth weight, especially if they require extra medical care.
• Infants with chronic or serious illnesses, which can weaken their ability to fight off infections.
• Babies with long-term intravenous (IV) lines, which slightly increase the risk of internal infections.
• Children undergoing medical treatments like chemotherapy, which can lower immune defenses.

In these cases, oral thrush isn’t just more likely’ it can also last longer or be harder to treat, making it especially important to monitor symptoms and follow your doctor’s advice closely.

What about older babies or children?

While oral thrush is most common in newborns, older babies, and young children can get it too, especially if they:

• use inhalers with corticosteroids (often for asthma) without rinsing their mouths afterward.
• eat a diet high in sugar, which can feed the fungus and lead to overgrowth.
• take antibiotics frequently, which (just like in infants) can disrupt the balance of good bacteria.

Thrush happens when the natural balance in your baby’s body is disrupted, and certain situations make it more likely. But knowing the causes, and which babies are at greater risk, can help you spot it early, treat it effectively, and even prevent it in some cases.

How to recognize oral thrush in infants

One of the first signs parents often notice white patches in their baby’s mouth. At first sight, these spots may look like traces of milk, but thrush has some specific characteristics that can help you distinguish it.

Thrush or milk? How to tell the difference.

Here’s how you can tell them apart:

Signs of oral thrush:

• looks creamy white or yellowish
• appears on the tongue, gums, inner cheeks, lips, or roof of the mouth
• resembles milk curds or bits of cotton
• doesn’t wipe off easily with a cloth or gauze
• may leave behind red, sore, or slightly bleeding skin when rubbed

Signs of milk residue:

• has a softer, more even texture
• stays mostly on the tongue
• wipes off easily with a damp cloth or gauze
• leaves the tongue looking pink and healthy
• doesn’t cause pain or irritation

Try this simple test: Gently wipe the area with a clean, damp cloth or gauze. If it comes off easily and the skin underneath looks normal, it’s likely just milk. But, if it sticks or reveals a red spot underneath, it might, in fact, be thrush, and it’s best to visit your pediatrician.

Other common symptoms of oral thrush in infants

Besides the white patches, other signs point to oral thrush:

• Feeding discomfort: Babies with thrush may start to nurse or bottle-feed, then pull away or cry in pain. It might hurt to suck because their mouths feel sore or irritated.
• Fussiness during or after feeding: Even outside of feeding times, babies may seem more irritable than usual, especially if their mouths are bothering them.
• Red tongue or cracked lips: In some cases, you might notice that the tongue looks red and inflamed, or  the lips are dry or cracked.
• Loss of appetite: Some babies may eat less than usual simply because their mouths hurt.
• Bad breath: While not common in young babies, some parents report a slightly sour or unpleasant smell from the mouth when thrush is present.
• Diaper rash: In some cases, the same fungus causing thrush can travel through the digestive system and cause a bright red, stubborn rash in the diaper area. This rash may not improve with regular diaper creams and can look shiny, inflamed, or have a red border.

If you notice white patches that don’t go away, your baby seems uncomfortable while feeding, or you also see a red rash in the diaper area, it’s a good idea to call your pediatrician. Thrush isn’t dangerous, but it can be unpleasant for your baby, and treating it early helps avoid extra discomfort or spreading.

Oral thrush treatment for babies

If you suspect your baby has oral thrush, the first and most important step is to schedule a visit to the pediatrician. The doctor usually diagnoses it by looking at the white patches and checking your baby’s symptoms. 

If it’s confirmed, the pediatrician will prescribe an antifungal treatment, depending on how severe the infection is and the specific areas that are affected.

Medical treatments for oral thrush in infants

In most cases, oral thrush improves after one to two weeks with proper care and treatment.

• Nystatin oral drops: This is one of the most commonly prescribed treatments. The drops are applied directly to the white patches in the mouth using a dropper or gauze, usually several times a day.
• Miconazole gel: In mild cases, a thin layer of this antifungal gel may be applied to the affected areas inside the baby’s mouth.
• Fluconazole: For infections that don’t respond to first-line treatments, doctors may prescribe fluconazole, an oral antifungal that works systemically. It’s typically used for more persistent or widespread infections.

These medications are safe for infants when used as directed, but follow your pediatrician’s instructions carefully, especially with dosage and duration.

Home remedies for oral thrush in infants

Alongside medical treatment, some safe, at-home practices may support healing and help prevent reinfection:

• Sterilize bottles, pacifiers, and toys daily during treatment to eliminate yeast contamination.
• Coconut oil has natural antifungal properties. Some parents gently apply a very small amount to the baby’s mouth or the mother’s nipples, but only after pediatric approval.
• Probiotics can help restore the balance of healthy bacteria. Probiotic drops are designed specifically for infants, but always consult your pediatrician first.
• Baking soda rinse: Mix one teaspoon of baking soda with one cup of cooled, boiled water. Use a clean cotton swab or gauze to gently wipe the inside of your baby’s mouth.

It’s essential to remember that home remedies are supportive and not a substitute for medical treatment. Always consult your doctor before using any new method with your baby.

How to prevent oral thrush in infants

While oral thrush isn’t usually serious, it can cause discomfort and feeding problems. The best way to avoid it is by following a few simple hygiene and care routines every day:

Keep everything clean

• Sterilize daily: Boil or wash in the dishwasher (if safe) all items that go in your baby’s mouth, bottles, pacifiers, teething toys, spoons, and breast pump parts.
• Wash well: Use hot water and soap to clean anything that touches your baby’s mouth or your nipples.

Hygiene for hands and skin

• Wash your hands before and after breastfeeding, changing diapers, or handling baby items.
• Wash your baby’s hands, especially if they crawl on the floor or chew on toys.
• Clean your nipples after feeding and let them air dry before putting your bra back on.

Breastfeeding care

• You can continue breastfeeding if your baby has thrush, but check for nipple pain, redness, or irritation, you might need treatment too.
• Sterilize all breastfeeding accessories daily: nipple shields, pump parts, bottles, etc.
• Change damp nursing pads often and wash nursing bras regularly to avoid moisture buildup.

Support the body naturally

• If your doctor recommends it, include probiotics or yogurt with live cultures in your diet, and your baby’s if they’ve started solids. These can help maintain a healthy balance of bacteria for everyone.

Extra tips to lower the risk

• Avoid unnecessary antibiotics, as they can upset the natural balance of good bacteria.
• Check your baby’s mouth regularly for white spots, especially after illness or medication.
• If you notice persistent white patches, irritability during feeding, or diaper rash, talk to your pediatrician.

Oral thrush is a common infection in babies, especially during the first few months of life. While it can cause some discomfort, like fussiness or trouble feeding, it’s usually not serious and can be treated easily with the help of a pediatrician. Knowing what signs to look for – like white patches that don’t wipe away – can help you catch it early and avoid extra discomfort for your baby.

With a little extra care, keeping bottles and pacifiers clean, practicing good breastfeeding hygiene, and paying attention to any changes in your baby’s mouth or mood, you can prevent thrush and stop it from coming back.