Oral thrush is a very common infection in infants that causes
irritation in and around a baby's mouth. It is caused by the
overgrowth of the yeast (a type of fungus) called Candida
albicans. Candida overgrowth can lead to vaginal (yeast)
infections, diaper rashes, or oral thrush. Most people
(including infants) naturally have Candida in their mouths and
digestive tracts, which is considered normal growth. The amount
is controlled by a healthy immune system and some "good"
bacteria. If the immune system is weakened (due to an illness or
medicines like chemotherapy), or if the immune system is not
fully developed as is the case in infants, the Candida in the
digestive tract can overgrow and lead to an infection. Sometimes
Candida overgrowth occurs 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,
infection can occur with the steroid use. Oral thrush can affect
anyone, although it's most common in i