Mouth ulcer under lip

An ulcer under the lip is an open sore in the oral lining, often caused by minor trauma or a canker sore, but persistent ulcers need examination.

The tissue under the lip is non-chewing oral mucosa, where a shallow ulcer can form after biting, friction, or local inflammation.

Aphthous ulcers are usually painful and shallow. Other causes include a sharp tooth, broken filling, hot food, irritants, infection, or a systemic condition, so appearance and duration matter.

Avoid spicy or acidic foods, use a soft brush, and keep the area clean without picking it. A pharmacist or dentist can advise on a suitable protective or pain-relieving treatment.

Arrange dental or medical assessment if the sore is unusually large, keeps returning, lasts longer than expected, or is associated with fever, weight loss, a neck lump, or difficulty swallowing.