Ulcer on inside lip
An ulcer inside the lip is often a shallow sore from trauma or a canker sore, but a persistent or unusual lesion needs examination.
The short answer
An ulcer inside the lip is usually a shallow inflamed break in the lining caused by local trauma or a canker sore, but a persistent or unusual lesion needs examination.
How can the inner lip become irritated or injured?
The inside of the lip is lined by soft oral mucosa that can be injured by biting, a sharp tooth edge, braces, or a rough restoration. A canker sore is a non-contagious ulcer that typically has a pale base and a red border.
What can you do to protect an ulcer inside your lip?
Avoid biting or rubbing the area and choose softer, cooler foods while it heals. Use a soft toothbrush, keep the mouth clean, and ask a pharmacist or dentist about a suitable topical product if eating is painful.
When does an inner-lip ulcer need dental assessment?
Arrange an examination if the ulcer lasts longer than expected, repeatedly returns in the same place, enlarges, bleeds, feels firm, or is accompanied by a neck lump or difficulty swallowing. A dentist can check for a sharp tooth, appliance irritation, infection, or another mucosal condition.
What should you ask about irritation inside your lip?
Ask whether a tooth, filling, denture, or orthodontic component is rubbing the sore. Ask what features would require follow-up and whether the lesion should be photographed or referred for further testing.
Frequently asked questions
Are ulcers inside the lip contagious?
A typical canker sore is not contagious. Sores caused by some viral infections have different appearances and may spread through contact.
Why does the ulcer keep coming back?
Repeated trauma, canker sores, irritation, and some medical conditions can cause recurrence. The pattern and examination help distinguish them.
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Who wrote this page
This library is published by Dental Nation, a licensed dental group practising in the United Arab Emirates. Pages are written and overseen by the same clinical team that treats patients in our clinics, and are held to a fixed editorial standard for safety and accuracy.
This page is patient education, not medical advice, and cannot replace an examination. Anything urgent — facial swelling, trauma, uncontrolled bleeding or severe pain — needs a dentist or emergency care now.