Symptoms & conditions
Mouth ulcers
The short answer
Most mouth ulcers heal in 7-10 days on their own. See a dentist if: an ulcer lasts more than 3 weeks, appears in the same spot repeatedly, bleeds, or sits under a rough filling or denture. Recurrent ulcers can signal nutritional deficiency or Behçet's disease.
What's happening
The clinical picture
Common aphthous ulcers are small (2-5mm), white or yellow with a red halo, painful but harmless, caused by minor trauma (accidental bite), stress, or citrus/sharp-food irritation. They resolve in 7-10 days with no treatment. Concerning ulcers are the ones that don't: persistent for 3+ weeks (could be early oral cancer), always on the same spot (usually trauma from a rough tooth edge or ill-fitting denture), or multiple recurrent ulcers (nutritional — B12, folate, iron — or systemic like Behçet's). Chlorhexidine mouthwash or topical steroid gel eases pain; cause-finding is the real fix.
Warning signs
Contact us the same day if:
- Ulcer lasting more than 3 weeks
- Painless white or red patch that won't wipe off
- Ulcer that bleeds or keeps growing
- Multiple recurrent ulcers (6+ per year)
- Ulcer on the side of the tongue in a smoker
What we do
Our approach
Oral exam with magnification. Photograph the ulcer for comparison. Identify trauma source (rough tooth, sharp filling, denture edge) and smooth/adjust. For recurrent ulcers: refer for nutritional blood tests. For any ulcer not healed by 3 weeks: biopsy — routine, 10-minute procedure — to rule out malignancy. Oral cancer caught early has a 90% 5-year survival rate.