Multiple choice general knowledge when a baby's tounge turn white it is called: thrush diaper rash internal yeast infection milk rash Reveal answer Fill a bubble to check yourself A Correct answer Explanation White coating on a baby's tongue is oral thrush, a common yeast infection (Candida albicans) in infants. Diaper rash affects the diaper area, milk rash is different, and internal yeast infection would have other symptoms.