Oral thrush in babies and adults

Oral thrush is an infection with Candida, a yeast that normally lives in the mouth and sometimes overgrows. It happens when your defenses are low or when the normal bacteria in the mouth are killed off, for example after antibiotics. In Puerto Rico many people call it algodoncillo or hongos en la boca.

It is not the same as canker sores, which are round, painful ulcers, or cold sores, which are blisters on the lip. Thrush patches are white, look like cottage cheese and may bleed a little if you scrape them.

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Oral thrush is handled in a US$79 doctor visit, the same price for every age, with no membership. You pay by card when you request the visit, and you get a full refund if the visit can’t take place. We do not bill insurance; the lab and the pharmacy charge separately. See all prices.

The CDC and MedlinePlus describe these signs:

• White patches on the tongue, the roof of the mouth or inside the cheeks
• Redness or soreness in the mouth
• Slight bleeding when the patches are scraped or when you brush
• Pain when swallowing

Babies, especially newborns, are at higher risk: the CDC says risk is highest in babies under 1 month old. You see white patches on the tongue and gums that do not wipe off easily, unlike leftover milk. Some babies do not want to feed, and the yeast can pass into the stool and cause a diaper rash.

If you breastfeed, you are both treated. Thrush can pass between a baby and the nursing parent’s nipples: deep-pink, cracked or sore nipples during and after feeds. MedlinePlus says that if you both have the infection, you both need to be treated at the same time, or you keep passing it back and forth. In the visit the doctor evaluates your baby and you. If you also have a red, warm, painful area on the breast, see mastitis.

We see babies and children of all ages: the doctor evaluates your baby by video with you on camera and, if appropriate, prescribes an antifungal for the mouth. Patients under 21 need a parent or legal guardian on camera with ID. See our online doctor for kids.

At home, boil or sterilize bottles, nipples and pacifiers after each use, and change diapers often.

In an adult, thrush almost always has a reason behind it. The doctor looks for it with you, because treating the cause keeps it from coming back. The CDC and MedlinePlus name these:

• Diabetes, especially with high blood sugar. Puerto Rico has the highest rate of diagnosed diabetes in adults of any US state or territory: 14.4% in 2021, according to the CDC.
• Steroid inhalers for asthma or COPD. The CDC recommends rinsing your mouth or brushing your teeth after each use; see also adult asthma treatment.
• Dentures, especially if they do not fit well. Clean them every day; if they hurt or move, we refer you to a dentist to have them adjusted.
• Recent antibiotics.
• Dry mouth from medicines or a health condition, and smoking.
• A weakened immune system: HIV, cancer, chemotherapy or medicines that lower your defenses.

Oral thrush is treated with an antifungal. According to the CDC, it can be topical (a rinse or a lozenge) or a pill, depending on the type and severity of the infection. The doctor chooses the treatment and how long it lasts for your case. In newborns, thrush sometimes clears on its own in a few days.

If thrush keeps coming back, or you are an adult with no clear cause (no inhaler, no dentures, no recent antibiotics), the doctor gives you a lab order for a lab near you: for example, glucose and A1C to check for diabetes. If you agree, an HIV test too; read more about HIV testing. If you are already our patient, we go over the results with you in a US$49 follow-up visit.

If it hurts or is hard to swallow, the infection may have reached the esophagus (esophageal candidiasis). That needs an in-person evaluation, because the esophagus sometimes has to be looked at from the inside; the doctor tells you where to go. The same applies if your immune system is very weak (HIV, chemotherapy, a transplant) and you get thrush, or if thrush does not improve with treatment.

For your safety, go to the emergency room or call 911 if you notice:

• You cannot swallow liquids or your own saliva, or you drool because you cannot swallow
• A baby who will not feed and has far fewer wet diapers, or is very listless
• A baby under 3 months with a temperature of 100.4 °F (38 °C) or higher
• Fever with a weakened immune system (HIV, chemotherapy, a transplant)