Persistent mouth sores: a three-week rule that could reveal something serious
A mouth ulcer that lasts more than three weeks should be checked by a clinician, as persistent sores can indicate oral cancer or other conditions even though most are harmless. Early diagnosis improves treatment outcomes, and a biopsy may be used to confirm cancer if the ulcer seems suspicious; seek medical care especially if the sore is painful, bleeds, or is accompanied by difficulty swallowing, a lump, or other warning signs.