The most surefire way is to check in with a dental professional, i.e. your dentist.  They’re trained to look for distinctive white lesions in your tongue, throat, inner cheeks, and etc.  If you try to scrape the white lesion area away, chances are that you’ll see a reddened and tender area, which may lead to eventual small bleed.  Your dentist should be able to perform a microscopic exam that will solidify the diagnose.

In more severe cases, the oral infection may spread to other parts of your body, most commonly your esophagus.  If that’s the case, other exams are required. Typical test are likely to consist of a throat culture, or performing an endoscopy of your esophagus, stomach, and other infected area.  Your doctor may also choose to perform an X-ray of your esophagus.

If you’re performing a self-diagnostic, one of the easiest things to notice is itchiness, or in the case of Oral Candidiasis, look for a thick white deposit inside your mouth. Do not try to get rid of these deposit, they will likely lead to bleeding, pay a visit to your dentist.