The risk of these infections varies based on the presence of certain underlying medical conditions. There are a number of other lesions that can also appear with oral thrush. Some are painful, some are unsightly and some may be a sign of something more serious. In addition to the distinctive white mouth lesions, infants may have trouble feeding or be fussy and irritable. What causes oral thrush?
If you have a weakened immune system, thrush may spread to your esophagus or other parts of your body.