Signs and symptoms of oral infection by Candida species may not be immediately noticeable but can develop suddenly and may persist for a long time. The infection usually appears as thick white or cream-colored deposits on mucosal membranes such as the tongue, inner cheeks, gums, tonsils, and palate. The infected mucosa may appear inflamed (red and possibly slightly raised) and sometimes have a cottage cheese-like appearance. The lesions can be painful and will become tender and often bleed if rubbed or scraped. Cracking at the corners of the mouth, a cottony-like sensation inside the mouth, and even temporary loss of taste can occur.^[2]

In more severe cases, the infection can spread down the esophagus and cause difficulty swallowing - this is referred to as Esophageal candidiasis. Thrush does not usually cause a fever unless the infection has spread beyond the esophagus to other body parts, such as the lungs (systemic candidiasis).^[3][4]

In addition to the distinctive lesions, infants can become irritable and may have trouble feeding. The infection can be communicated during breast-feeding to and from the breast and the infant's mouth repeatedly.^[2]