Certain germs normally live in our bodies. While most germs are harmless, some can cause infection.

Thrush occurs when too much of a yeast (a type of fungus) called Candida albicans grows in a baby's mouth. Germs called bacteria and fungi naturally grow in our bodies. Our immune system helps keep these germs in check. But babies do not have fully-formed immune systems. That makes it easier for too much yeast to grow.

Thrush often occurs when mother or baby has taken antibiotics. Antibiotics treat infections from bacteria. They can also kill good bacteria, and this allows yeast to grow.

The yeast thrives in warm, moist areas. The baby's mouth and the mother's nipples are perfect places for a yeast infection.

Babies can also get a yeast infection on the diaper area at the same time. The yeast gets in the baby's stool and can cause a diaper rash.

Symptoms of thrush in the baby include:

• White, velvety sores in the mouth and on the tongue
• Sores that may bleed when wiped
• Redness in the mouth
• Diaper rash
• Mood changes, such as being very fussy
• Refusing to nurse because of soreness

Some babies may not feel anything at all.

Symptoms of thrush in the mother include:

• Deep-pink, cracked, and sore nipples
• Tenderness and pain during and after nursing

Your health care provider can often diagnose thrush by looking at your baby's mouth and tongue. The sores are easy to recognize.

Your baby might not need any treatment. Thrush often goes away on its own in a few days.

Your provider may prescribe antifungal medicine to treat thrush. You paint this medicine on your baby's mouth and tongue.

If you have a yeast infection on your nipples, your provider may recommend an over-the-counter or prescription antifungal cream. You put this on your nipples to treat the infection.

If both you and your baby have the infection, you both need to be treated at the same time. Otherwise, you can pass the infection back and forth.

Thrush in babies is very common and can easily be treated. Let your provider know if thrush keeps coming back. It may be a sign of another health issue.

Contact your provider if:

• Your baby has symptoms of thrush
• Your baby refuses to eat
• You have symptoms of a yeast infection on your nipples

You may not be able to prevent thrush, but these steps may help:

• If you bottle feed your baby, clean and sterilize all equipment, including nipples.
• Clean and sterilize pacifiers and other toys that go in your baby's mouth.
• Change diapers often to help prevent yeast from causing diaper rash.
• Be sure to treat your nipples if you have a yeast infection.

Candidiasis - oral - newborn; Oral thrush - newborn; Fungal infection - mouth - newborn; Candida - oral - newborn

Balest AL, Riley MM, O'Donnell B, Zarit JS. Neonatology. In: Zitelli BJ, McIntire SC, Nowalk AJ, Garrison J, eds. Zitelli and Davis' Atlas of Pediatric Physical Diagnosis. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 2.

Harrison GJ. Approach to infections in the fetus and newborn. In: Cherry JD, Harrison GJ, Kaplan SL, Steinbach WJ, Hotez PJ, eds. Feigin and Cherry's Textbook of Pediatric Infectious Diseases. 8th ed. Philadelphia, PA: Elsevier; 2019:chap 66.

Updated by: Neil K. Kaneshiro, MD, MHA, Clinical Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.