Level 1: What are infant oral ulcers? Infant oral ulcers refer to painful ulcers that appear on the oral mucosa of infants and young children. It usually appears as small, pale white or yellow spots that gradually enlarge and form small ulcers. In severe cases, multiple oral ulcers may occur, which may even affect appetite and sleep. Level 2: Causes of Oral Ulcers in InfantsCauses of Oral Ulcers in Infants and Young Children