A canker sore is a small, painful, open sore inside the mouth that is white or yellow with a bright red border. It commonly appears on the inner cheeks, lips, tongue, roof of the mouth, or base of the gums. Canker sores are not contagious and are different from cold sores (fever blisters), which occur on the lips. They usually last 7 to 10 days and heal completely within 1 to 3 weeks without scarring in most cases.
Symptoms
- Painful, round or oval ulcer with a white or yellow center and red edges
- Tingling or burning sensation before the sore appears
- Common locations: inner cheeks, tongue, lips, gums
- Pain worsens with certain foods, chewing, or speaking
- Sometimes fever, malaise, or swollen lymph nodes if severe
Causes and Triggers
- Exact cause unclear but may include immune system issues, genetics, viral infections, or mouth injuries (dental work, biting the cheek)
- Nutritional deficiencies (iron, folic acid, vitamin B-12)
- Emotional stress and hormonal changes
- Food allergies
Types
- Minor canker sores: small, heal within 1-2 weeks without scarring
- Major canker sores: larger, deeper, last up to 6 weeks, may scar
- Herpetiform canker sores: multiple tiny sores that may cluster and merge, rare
Treatment and Outlook
- Usually heal on their own
- Over-the-counter topical treatments can ease pain
- Avoid irritating foods during sores
- Persistent, unusually large, or painful sores should be evaluated by a doctor
- Severe cases may require prescription treatments or cauterization
Overall, canker sores are a common, non-contagious oral condition with known triggers but uncertain exact cause. They cause moderate pain, usually resolve spontaneously, and rarely lead to complications.
