Canker sore on side of lip
A sore on the inner lip is often a canker sore, but persistent, spreading, or unusually painful lesions need dental assessment.
The short answer
A canker sore on the inner side of the lip is a shallow ulcer in the oral lining that usually heals on its own. It is not the same as a fluid-filled cold sore on the outer lip.
What is the direct answer?
What does this question mean?
The lesion commonly appears as a round or oval red sore with a pale centre. A bite, sharp tooth edge, irritating appliance, stress, or nutritional problem can contribute, while recurrent or unusual ulcers may have another cause.
What can you do next?
Rinse gently with salt water, avoid spicy or acidic foods, and use a soft toothbrush. Do not pick the ulcer; a dentist can smooth a sharp edge or prescribe a protective or anti-inflammatory treatment when needed.
When should you seek dental care?
Arrange an examination if the sore lasts beyond two weeks, keeps returning, is unusually large, or makes eating difficult. Seek prompt care for facial swelling, fever, trouble swallowing, or a lesion after significant injury.
What should you ask the dentist?
Ask whether the lesion fits a canker sore, whether a tooth or appliance is rubbing it, and whether an examination or blood test is appropriate for recurrent ulcers. Ask which topical treatment is suitable for your medical history.
Frequently asked questions
Can a canker sore spread by kissing?
Canker sores are not contagious; a cold sore on the outer lip is a different condition.
What if the sore keeps coming back?
A dentist can look for trauma, oral disease, medication effects, or medical factors linked with recurrent ulcers.