Canker sore inner lip

A canker sore on the inner lip is usually a shallow, tender ulcer that heals on its own, while repeated, large, or persistent ulcers need assessment.

A canker sore, or aphthous ulcer, is a break in the lining of the mouth with a pale or yellow center and a red margin. Minor trauma, stress, illness, nutritional problems, or an immune-related tendency may be associated, but an ulcer can also be caused by a sharp tooth or appliance.

Rinse gently with salt water, choose soft foods, avoid spicy or acidic items, and use a soft toothbrush. A clinician can recommend a topical corticosteroid or other treatment when pain or recurrence warrants it.

Seek care if an ulcer lasts longer than expected, keeps returning, is unusually large, bleeds, hardens, or occurs with fever, weight loss, or difficulty swallowing. A non-healing ulcer needs direct examination.

Ask whether a sharp tooth or appliance is rubbing the lip, whether the ulcer needs prescription treatment, and what pattern would justify testing for an underlying cause.