Cold sores inside lip

Cold sores are commonly grouped blisters caused by herpes simplex virus, while aphthous ulcers are shallow, painful ulcers inside the mouth. Biting, a sharp tooth, irritation, stress, and some illnesses can produce an inner-lip ulcer; examination distinguishes these from infection.

Rinse gently with salt water, use a soft toothbrush, avoid spicy or acidic foods, and do not pop or scrape the lesion.

Seek care if it lasts beyond two weeks, repeatedly returns, becomes unusually large, or comes with fever, eye symptoms, or difficulty drinking.

Ask whether the appearance fits an aphthous ulcer, trauma, viral lesion, or another condition, and what treatment is appropriate.