1. What is infant thrush? Infant thrush, also known as oral candida infection, is a common oral disease in infants and young children. The disease, which usually appears within the first two months of life and is caused by Candida, appears as white or yellow patches, sores, and redness and swelling in the mouth. These ulcers may cause feeding difficulties and discomfort. Although this infection usually does not have long-term effects on your baby\’s health, if left untreated, it may lead to the development of other infections. 2. Infant thrush