You can usually tell when you have a mouth sore without needing a healthcare provider’s diagnosis. However, you should see your healthcare provider if you: have white patches on your sores; this may be a sign of leukoplakia or oral lichen planus; have, or suspect you may have, herpes simplex or another infection; have sores that don’t go away or get worse after a couple of weeks; started taking a new medication; started cancer treatment and recently had transplant surgery.
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